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CalCORE Research: Controlling Soilborne Diseases in California's Strawberry Industry with Anaerobic Soil Disinfestation (ASD)

mer, 2019/07/10 - 17:00

Watch this video at https://www.youtube.com/watch?v=uxHs2eM7YzY&t=28s

Chapter 1: The Threat of Soilborne Disease to California's Strawberry Industry

Mark Bolda: I think in many ways the soilborne diseases are probably the most constraining of the diseases and pests that we face in strawberries. Watsonville is a community that is supported by the strawberry industry. If as an industry we start to lose farms because we can't handle these soilborne diseases, that would be a tragedy.

Joji Muramoto: In this area, thanks to the climate, strawberry harvest usually starts in late March and continues until October or even November. But if plants have soilborne diseases, harvest can finish in June or July—so that is very big damage for growers. There are three major soilborne diseases of strawberries in California: Verticillium dahliae, the pathogen that causes Verticillium wilt; Fusarium wilt caused by Fusarium oxysporum; and charcoal root rot caused by Macrophomina phaseolina.

 

Steve Pederson: Verticillium is probably the number one most problematic soilborne disease. The problem with being a diversified organic grower is that we grow lots of vegetables that are potential hosts.

Chapter 2: Anaerobic Soil Disinfestation (ASD): Principles and Mechanics

Joji Muramoto: Anaerobic Soil Disinfestation, known as ASD, is a biological process that can control a range of soilborne pathogens using the principle of acid fermentation. There are three steps to doing ASD. The first step is to apply a readily decomposable carbon source to the soil, which increases the microbial activity in a very short period of time. Then we cover the soil with plastic. Then we use drip tape to saturate the pore space with water, which starts the anaerobic digestion of the carbon source we incorporated. We usually leave it for three weeks, during which anaerobic decomposition, like a fermentation process, takes place.

Carol Shennan: These fermentation processes are the key to a lot of the disease suppression that we get with ASD. When there is no oxygen in the soil, bacteria have to use other pathways than the normal respiration pathways to break down the carbon. And there are various byproducts produced—organic acids, volatiles—that are toxic to certain pathogens and pests. Different microbes flourish under that new environment. Not only is it different, but there are actually more bacteria and more fungi than we started with. So it’s not sterilizing the soil in any way—in fact we’re creating more biological activity in it—it’s just a different kind of community. One of the interesting things about that, is that it seems like that may confer some ability of the soil to resist future disease. It’s great to be able to control something immediately, but it’s even better if you can make a soil that’s more resistant to reinfection down the road. 

Chapter 3: ASD: A Biological Process

Carol Shennan: With ASD, we are relying on the soil microbial community to do the work for us and they require particular conditions. We have to be careful about the soil temperatures when we do ASD. For certain pathogens like Verticillium, soil temperatures of around 70-75 degrees F are fine, but for other pathogens like Fusarium wilt, you need to have much higher soil temperatures for ASD to effectively control it. We have even found that the carbon source may be important—some carbon sources are better able to control a particular pathogen than another. How to manage the water to get good anaerobic conditions is going to be different if you have a heavy soil than if you have a more sandy soil.

That’s where we are with the ASD work at this point—we know that it can work for some things in some places, and now we are trying to work out how to optimize it for particular locations and particular pathogens.

Chapter 4: ASD: Growth & Challenges

Carol Shennan: Four or five years ago we had maybe 1 or 2 acres being tested. In the fall of 2014 we had 1,000 acres—which is a huge growth rate—and that wouldn’t have been possible without the partnership that we built from the beginning with a local company called Farm Fuel who imports all the carbon material, and they also provide technical assistance to the growers on how to do ASD. That has been really important—having that capacity to scale up.

Tim Campion: The potential of ASD that we have seen is favorable results with increase in yields in the plants, and overall health of the plants. It is pretty obvious just looking out in the field—comparing the ASD plants with the rows right next to it—the vigor of the plants and the health, and the stronger plants, better pest-resistance and disease-resistance. One concern is the cost with the increased labor and materials.

Jaime Lopez: Our first year doing ASD was only a 5-acre test plot and each year it has doubled. Right now we are at about 120 acres and we are about to add more acres in our other districts. The hurdles that we have when applying ASD is that we have a very scarce labor force. So trying to have a turnaround time of one week incorporating the ASD into the soil—putting the mulch, putting the drip tape, irrigating within a week’s time—I think is one of the biggest issues that we have.

Carol Shennan: The most successful growers with ASD start off doing it on a small area, working out the kinks and then scaling it up. Because it is a lot, you need to be able to have a way to get the carbon into the soil, get the beds made, and get the plastic on and apply the water as quickly as possible. Otherwise, that carbon is broken down aerobically, which won’t have the benefits.

There are a lot of mechanics to work out. We really recommend that growers talk to other farmers who are doing it, about how they have been able to get it to work, and then try it in a small area first.

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15424

CalCORE: Connecting California Farmers and Scientists to Improve Rotational Strawberry and Vegetable Systems

mer, 2019/07/10 - 16:57

Watch this video at https://www.youtube.com/watch?v=w_1UbP8IvEk

CalCORE: Connecting California Farmers and Scientists to Improve Rotational Strawberry and Vegetable Systems

Joji Muramoto: When I started to do research and soil testing for farmers, when I saw they appreciated the data I provided, I realized, "Oh, I can do something for them. Doing something useful for farming...that has been my passion."

Diego Nieto: In this region there is a very broad organic industry thatincludes both the large corporate growers and also the small-scale diversified growers. There are 49,000 acres of certified organic ground in two counties [Santa Cruz and Monterey] that is valued at close to $367 million. Seventy-five percent of the organic strawberries that are grown in California are grown in these two counties. So it is really a nice hot spot to do organic sustainable research in strawberry.

Goal 1: Building the CalCORE Network

Carol Shennan: The acronym CalCORE stands for California Collaborative Organic Research and Extension network. We have now, I think, more than 15 growers involved in one way or another with the network, plus many extension agents, and local organizations and industry people, as well as researchers from half a dozen different places.

Tim Campion: It has been a great collaboration. We pick up new information from them and they are always well organized and informative.

Steve Pedersen: I think the community elements of the CalCORE trial has been one of the major benefits for me. Some really good nuggets of information you'll pick up just standing on the sidelines and talking to people. And also being introduced to all the different researchers has been really valuable.

Carol Shennan: We have made a special effort to try and involve the Spanish-speaking farming community in the project by working with the organization ALBA, The Agricultural Land Based Association, who work to help farmworkers become organic farmers.

Nathan Harkleroad: It has been really important to do outreach to the Latino communities because so many Latinos are owners and operators of farms in our region, and particularly strawberries.

Goal 2: Researching Integrated Systems to Manage Fertility, Disease and Pests

Carol Shennan: The main research goal is to look at developing rotation systems that are both economic but also have a smaller environmental footprint as possible.Where we try to address issues of pests, and diseases and nutrients all in the same rotations, and that is really what the core of calCORE is.

There are a number of specific questions we are trying to ask. The first one is about length of rotation: How often can you grow strawberries? And, how do the particular crops you grow in rotation affect the health of the strawberries? Particularly in terms of disease management, because that is the main limitation for organic strawberries in many cases, is soilborne diseases.

Steve Pedersen: Our strawberries are by far our largest earning crop per acre, so most of our crop planning is centered around setting things up for a good strawberry crop. We have to be really careful in our rotations choosing where to grow things; a lot of the vegetables that we grow turn out to be hosts for verticillium in particular.

Carol Shennan: The secondary goal is to look at the use of anaerobic soil disinfestation or the addition of mustard seed meals as strategies for controlling disease. Each of those affects fertility, so we are also doing a lot of measurements of soil fertility. We are also interested in the biological control of important pests.

We ended up with quite a complicated study. One of the ways we've tried to cope with that and still get realistic information from the farms is that we are using something that is called a mother-baby design, where we have a big mother experiment where we do all the replications. And then the growers in the group decided on a subset of those treatments to test on their own farms, and those are the baby trials which we now have on 6 different farms.

Jaime Lopez: CalCORE has really helped us with learning more about new processes or better practices for organics. It has helped us in grounds where we do have high amounts of soil diseases, and it has helped us to suppress those soil diseases to have a better production.

Rigoberto Bucio: Now with this project for which I was fortunate enough to be invited, I have learned it is necessary to do soil analysis, and to carry things out in an orderly way. I learned that sometimes if we don't do soil analysis, we unknowingly apply too much fertilizer.

Steve Pedersen: There are some pretty major benefits. And one of those, and it has been reinforced by the CalCORE experiments, is the importance of using broccoli as a rotational crop for strawberries, which is something we do pretty much across the board now. And getting introduced to the concept of ASD, anaerobic soil disinfestation, is another one and I think that shows great promise.

Carol Shennan: You really have to have the perspective of the farmers because they know their systems in ways that as a researcher I can never know. I can get really excited about some basic science questions, don’t get me wrong, but my real passion is how can we use scientific knowledge to help improve the productivity, ecology; and the human dimensions of our agricultural systems.

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 15423

Video: Addressing Critical Management Challenges in Organic Cucurbit Production

mer, 2019/07/10 - 16:41

eOrganic authors:

Jason Grauer, Cornell University

Myra Manning, Cornell University

Lindsay Wyatt, Cornell University

 

Watch this video at https://www.youtube.com/watch?v=pRvonR1lSsI

Video Transcript

Organic growers are facing many challenges limiting their production of cucumbers, melons and squash. If you have ever tried to grow these crops in the eastern United States, you've probably had to deal with aphids, striped cucumber beetles, or downy mildew, but now there's hope. A NIFA-OREI grant known as ESOCuc, the Eastern Sustainable Organic Cucurbit Project, addresses these issues. ESOCuc is a collaboration of growers, extension agents, and university researchers working together to find solutions for you.

The ESOCuc project has four objectives:

  • To evaluate the most popular varieties so growers can access updated information on yield and disease resistance
  • To breed new varieties, guided by grower input, which will be made available through organic seed distributors
  • To examine and improve management strategies to tell you what works against these pests and what doesn’t
  • Finally, to make all this information readily available through online resources, webinars, and field days

For the past several decades, the seed industry has focused most of its attention on developing varieties for conventional farms. There has been little breeding specifically for the needs of organic farmers. It is clear that we must work directly with organic growers to solve this issue. As part of ESOCuc, we are evaluating popular cucurbit varieties to compare their performance in an organic environment, on research farms as well as collaborating organic production farms.

The Organic Variety Trial Database is currently available for finding information on potential variety choices. With our trials, we are looking to improve this resource to include precise measurements of varietal susceptibility to viruses, downy mildew, and striped cucumber beetles so that you can be well informed about what you are getting. Along with the trials run by Cornell Cooperative Extension in NY, Jeanine Davis is leading a set of evaluations at the Mountain Research Station in North Carolina and John Murphy is leading another set in Auburn, Alabama.

One focus of ESOCuc is controlling aphid-vectored viruses. When virus pressure increases in the early summer, growers may lose their whole crop. Even with the use OMRI-approved pesticides, aphids can still transmit viruses before the pesticide kills them. This has been an ongoing problem in the Southeast, but thanks to climate change, the Northeast may soon face these viruses as well. John Murphy of Auburn University and his team are developing a planting strategy that removes the virus from the aphids as they feed, reducing the risk of virus transmission into your fields. This strategy will be described on the eOrganic website and demonstrated at field days in Alabama.

Downy mildew is a wind-transmitted pathogen that affects all cucurbits. As you may already know, susceptible varieties can become completely defoliated within weeks of the disease arriving in the field. Cucurbit growers haven’t been overwhelmed by downy mildew for decades, but now new strains are on the rise. This new downy mildew has overcome previously resistant varieties and we need new strategies to combat it.

On the CDM-IpmPIPE disease prediction software, we can observe the disease patterns as downy mildew moves up the coast with tropical storms, and with winds from the west. CDM-IpmPIPE relies on reports from growers like you to track the movement of downy mildew. The more people use this resource, the more accurately users can anticipate the disease's arrival and determine when to start using OMRI-approved pesticides. Peter Ojiambo at North Carolina State University is working to make this system even better and more accurately forecast chemical control needs. We hope that you will become one of the growers that uses this resource.

In addition to evaluating varieties for resistance in the field, we will perform trials inside high tunnels to test drier environments that are less hospitable to the disease. You will have access to information about these control strategies as we pull together the data from management trials.

Striped cucumber beetles feed on the leaves, roots, and fruit of cucurbits—damaging plants and decreasing marketability. They can also spread bacterial wilt and squash mosaic virus between plants. The availability of systemic pesticides for conventional growers has really limited the investment in developing tools for organic systems. We’re working to close that gap.

In addition to looking at the economics of physical barriers like row covers, we’ll be providing enhanced trap-cropping strategies based on an understanding of what attracts beetles to cucurbits in the first place. We have noticed beetles have strong preferences for certain cultivars so we can direct breeding to incorporate low beetle preference. We will be able to accurately describe varietal susceptibility to beetle damage, making it easy for you to select the right strategy for your farm.

Popular cucurbit cultivars with consumer-desired characteristics often lack genetic resistance to pests. We’re working to develop cucumber, melon and squash cultivars that are open-pollinated, regionally adapted, tolerant to pests, flavorful, and prolific. A key to making this process work is grower input. We use surveys at meetings and conferences, needs assessments by the Organic Seed Alliance, and the direct feedback we get through on-farm evaluations of developing varieties. You can help guide this process by participating in these surveys to let us know what’s important to you. Outreach and extension are vital to this project’s success. All the work we’ve described is focused on grower needs, so success is dependent on our collaboration.

Our research will engage farmers and extension educators as active participants through on-farm trials, demonstrations, field days, workshops, and regional meetings. We encourage your continued feedback and even if you’re unable to attend one of these events, we hope you’ll find the information on cultivars, management strategies, and economics on eOrganic useful on your farm.

If you've seen cucurbit downy mildew on your farm, or are interested in learning how to recognize it, please consider participating in the CDM-IpmPIPE. The grower you help just might be yourself! To learn more about the ESOCuc project, visit the website or contact your local extension office for field day and meeting information. To receive updates on eOrganic/eXtension webinars relating to this research, sign up for the eOrganic newsletter at http://eOrganic.info.

Additional Resources

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 9974

Efficient Intercropping for Biological Control of Aphids in Transplanted Organic Lettuce

mer, 2019/07/10 - 12:30

eOrganic author:

Eric Brennan, USDA Agricultural Research Service, Salinas, CA

Watch this video at https://www.youtube.com/watch?v=KVLgt2_J1Wk

How do organic farmers control aphids and produce high quality lettuce without pesticides? With naturally occurring beneficial insects like hoverflies that eat aphids live! Farmers attract these good bugs into the field by intercropping lettuce with flowers like alyssum. This video shows how this system works, and a more efficient and novel way to achieve biological control of aphids with less land area and fewer weed problems. It is based on research by Eric Brennan at the USDA Agricultural Research Service during 9 years of commercial scale organic lettuce production in the Salinas Valley, California.

This video was modified from a video presentation at the American Society of Horticulture annual conference in July, 2013.

Click following link to download a pdf of a related publication (Agronomic aspects of strip intercropping lettuce with alyssum for biological control of aphids)

Agronomic Impacts of Strip Intercropping Lettuce with Alyssum for Biological Control of Aphids

Video Transcript

Hi everybody. My name is Eric Brennan. I’m a scientist at the USDA Agriculture Research Service based in Salinas, California. Salinas valley opens to Monterey Bay, which acts as a natural air conditioner for much of the area. This climate is ideal for lettuce and the gross production value for lettuce here was nearly $1.3 billion in 2012. I’ve worked here since 2001, and my research over the past 12 years has focused on high value, organic production systems. Today, I’ll share some of the lessons I’ve learned over the past 10 years on how to use intercropping to biologically control aphids in transplanted organic romaine lettuce.

When you cut into a head of romaine lettuce, you can get a nice view of the densely packed interior leaves. Unfortunately, the most important insect pest of lettuce in California is a nasty aphid species that likes to infest this interior area and is easy to see. Intercropping or interplanting lettuce with plants that flower quickly like alyssum is a common and effective strategy that organic farmers in this region often use to control aphids. Alyssum is referred to as an ‘insectary plant’, because when it's intercropped with lettuce it attracts naturally occurring beneficial insects, like hoverflies, into the field. Hovering in midair requires lots of energy which the adult hoverflies get from the sugary nectar of the alyssum flowers. The pollen provides the adults with the protein that they need to reproduce. After feeding on the flowers, the females fly through the field searching for lettuce plants where they will lay their eggs. The females prefer to lay eggs on lettuce plants with aphids because the larvae that hatch from the eggs in a few days, feed on the aphids. I like to think of aphids as walking milkshakes for hoverfly larvae. Infact, the larvae of some hoverfly species can eat up to 150 aphids per day before they mature into flying adults.

In highly disturbed agricultural landscapes such as those used for vegetable production in Salinas, the presence of hedgerows around the farm and the frequent use of annual cover crops help to protect and maintain populations of beneficial insects year round. These habitats and the use of insectary intercrops, like alyssum, enhance the ability of beneficial insects to control economically important pests like aphids. We refer to this pest management strategy as Conservation Biological Control.

Let’s now move to the USDA organic research farm, where I’ll share how my approach to intercropping alyssum and lettuce has become much more efficient over the past 10 years. This 23 acre site includes an ongoing, long-term, organic systems experiment where we have grown 2 acres of romaine lettuce, broccoli, and strawberries on a commercial scale in rotation with various cover crops and compost rates over the past 10 years. Today, I’m going to focus on the intercropping practices we used to maximize the potential marketable yields during 9 years of lettuce production. This research is partially funded by the wholesale of marketable vegetables from the experiment. Therefore, in order to continue the research, I highly was motivated to maximize the marketable yield and the efficiency of the lettuce production.

Here are some details about the management of the lettuce that were consistent across years. A gps guided tractor was used to form beds that were 40 inches wide, into which we injected preplant organic fertilizer. After bed shaping, the lettuce was transplanted in two lines 12 inches apart with 11 to 12 inches between plants within each line. The transplants were approximately 30 to 35 days old at transplanting. Transplanting was usually during the first 10 days of May except during the year 3 when rains delayed it until late May. Sprinkle irrigation was used as needed to establish the transplants, but drip irrigation was used for most of the season. Liquid organic fertilizers were injected through the drip tape approximately 30 days after transplanting. Weeds were controlled by tractor cultivation and by hand weeding once during each crop. And the lettuce was harvested at maturity 39 to 49 days after transplanting.

The alyssum insectary plants were concentrated in 8 of the 48 total beds in the field. Notice that alyssum beds 1 and 8 on the edges of the field were single alyssum beds, followed by 10 beds of lettuce, then 2 beds of alyssum and 10 more beds of lettuce, etc. This picture shows 4 different alyssum varieties including the sweet variety that is the typical insectary variety in California. The alyssum and lettuce in the background were all transplanted 46 days ago and it's clear that sweet alyssum is much more vigorous and bushy than the three ornamental alyssum varieties shown here.

I’ll now highlight 3 major changes in the way that lettuce was intercropped with alyssum during the 9 years and explain my rationale for making each change. The first change occurred after year 2 and involved switching from using alyssum seed to using transplants to establish the insectary beds. Alyssum seed is extremely small and the seed of the sweet variety used for insectaries is also inexpensive. During the first two years, I thought that direct seeding alyssum would be more cost-effective than using alyssum transplants. However, direct seeding alyssum in dense lines in the field had two major problems. I’ll use a few drawings to illustrate the first problem that involved weed management.

This drawing shows a single bed with the two transplant lines of lettuce approximately 2 ½ to 3 weeks after transplanting. The field is ready to hand weed at this stage and the red dots represent emerged weeds. Note that the weeds had already been removed from the bed center and furrow by tractor cultivation. Hand weeding in a situation like this is relatively easy, because the weeds are small and easy to distinguish from the larger and evenly spaced transplants. This drawing shows weeds interspersed with 2 lines of direct seeded alyssum plants. The green dots are the densely seeded alyssum plants and the red dots are the weeds. Note that the density and location of the weeds here is the same as in the previous drawing with lettuce transplants. However, in this case, the weeds and alyssum emerged together and if had not colored the weeds red they would be very difficult to distinguish from the alyssum plants. As you can imagine this was extremely difficult to hand weed and the situation only got worse as the weeds and alyssum plants got bigger and tangled together. Furthermore, many weeds in direct seeded alyssum lines escaped control and produced seed that added to the weed seed bank.

The second major problem with direct seeding alyssum in transplanted lettuce is that even in the summer, alyssum seedlings often need to grow for about a month before they begin flowering. In fact, this alyssum seedling didn’t flower until it was 36 days old. In contrast, alyssum transplants are usually flowering at transplanting. Early flowering of the insectary plants is important for transplanted crops like lettuce that may be harvested at 39 to 49 days after transplanting.

The fact that lettuce from the first two years was not infested with aphids suggests that flowering from direct seeded alyssum was adequate for biological control. However, the cost of alyssum transplants seemed worthwhile for both weed control reasons and the likely benefits of earlier flowering for biological control of aphids. After 4 years of successful lettuce production without any major aphid problems, I wondered if I could reduce the amount of space allocated to alyssum and still control aphids. The 8 beds devoted to alyssum during the first 4 years were obviously effective, but they were also reducing the area for lettuce by 17%. This displacement of lettuce for insectary plants is a major concern for farmers in Salinas where the land rents are high.

The last two intercropping changes I’ll discuss are 2 approaches I used to reduce the field area that was displaced by insectary plantings. This photo shows the intercropping pattern during years 5 to 7. Notice, that rather than 8 solid beds of alyssum that were used during the first 4 years, the insectary beds now included 1 line of alyssum and 1 line of lettuce. This still provided excellent aphid control, and boosted lettuce yields by 8% because there were 8% more lettuce plants in the field.
Let’s now move onto the last intercropping change that was the most radical. This change was inspired by a competition experiment with alyssum and lettuce that I conducted during years 5 and 6. As you can see I tried all kinds of crazy combinations.

All the details are described in this recent publication. However, I’ll describe the most exciting results from this experiment with a simple addition equation. If we add the transplants from one bed of lettuce to the transplants from one bed of alyssum we get an intercropping pattern that has twice the normal transplant density. We call this additive intercropping because we added the two densities together. There's obviously more competition in the additive pattern because it’s more crowded. The amazing thing about this additive pattern is that the increased competition only reduced lettuce biomass by about 25% and alyssum biomass by about half compared with when they were growing separately on beds of their own. I’ll now show how the information from this competition experiment was used to improve the efficiency of intercropping lettuce and alyssum during years 8 and 9.

Here’s what the field looked like 20 days after transplanting during year 8. You might be wondering what’s happened? Where’s the alyssum? That question “Where’s the alyssum?” reminds me of a well-known and beautiful song by Pete Seeger. Sing along if you like as I play a line or two on my guitar.

[Music]. Where have all the flowers gone?
[Music]. Long time passing.
[Music]. Where have all the flowers gone?
[Music]. Long time ago.

That’s a great song, but let me answer the question: Where are the alyssum flowers? Here’s the field 44 days after transplanting and about a week before harvest during year 8. There are lots alyssum flowers out there but they’re just not as obvious as in the previous years where alyssum displaced lettuce. Here’s another shot the next day when the lighting made it easier to see the alyssum. I want to point out two things in this picture. First, notice that most of the alyssum is still concentrated in a few beds. These are the same 8 insectary beds that were used during the previous years. This close up shot shows the additive pattern that we used on the insectary beds during year 8. Notice that there's only 1 alyssum transplant every 3 lettuce transplants in 1 line of the bed. A similar additive pattern was used during year 9 except that there was only 1 alyssum transplant between every 5 lettuce transplants in 1 line of each bed.

This figure with white symbols to represent alyssum, illustrates the difference in the extremely intense additive intercropping pattern that was used in the competition experiment described earlier, compared with the additive patterns that were used during years 8 and 9. The intercropping patterns used during these last 2 years were designed to reduce the potential for competition between alyssum and lettuce. In fact, in a subsequent study, I found that there was no difference in the marketable weight of a box of a lettuce from beds with the additive pattern used during year 8, compared to the weight of a box of lettuce from beds without any alyssum. This is a very important point because it means that with these less intense additive intercropping patterns, we can a produce alyssum flowers for beneficial insects without losing any of lettuce yield. The second thing I want to highlight about the additive intercropping patterns used during years 8 and 9 are these lines of alyssum that ran perpendicular to the bed direction. If you looked at the field from the top it would be a grid like this with the insectary and lettuce beds running from the bottom to the top of the figure and the perpendicular lines running from the left to right. You might wonder why we added the perpendicular lines during years 8 and 9 to create this grid pattern. This was done because I was concerned that the relatively low intensity additive pattern on the 8 insectary beds alone might not provide quite enough alyssum flowers to encourage hover fly movement through the whole field. However, I really don’t know if this concern was justified.

You might be wondering how we created this additive pattern through the field. First, we transplanted lettuce across all 48 beds using a tractor drawn transplanter. And then in one line on the 8 insectary beds, by hand we inserted one alyssum transplant between every 3 or 5 lettuce plants, during years 8 and 9, respectively. For each of the 9 perpendicular lines, we walked across the beds and inserted one alyssum transplant by hand between two lettuce plants in one line for each bed. Our lettuce yields were highest these last 2 years when we used the additive intercropping approach because alyssum didn’t displace any lettuce.

I’ll summarize my experience with intercropping lettuce with alyssum over the 9 years with 2 figures. This first figure shows the dramatic change in the amount of lettuce that was displaced by alyssum over the years. Based on my experience, I highly recommend this additive intercropping approach for transplanted lettuce because it is much more land efficient, it didn’t reduce marketable head weight, and yet it still provided beneficial insect like hoverflies with the food they needed to survive and control aphids.

This last figure illustrates how the density of alyssum transplants changed over time. It is interesting to note that we achieved excellent aphid control all year despite the drastic reduction in the number of alyssum transplants per acre. This experience leads me to conclude that during the first 7 years we were providing far more alyssum flowers for the hoverflies than was necessary. I estimate that additive intercropping with about 500 to 1000 alyssum transplants per acre, distributed throughout the field should provide sufficient pollen and nectar for hoverflies to control aphids in transplanted romaine lettuce.

I hope this presentation has helped you to understand the value and complexity of intercropping lettuce with insectary plants like alyssum for biological control of aphids. Thanks for watching, and stay tuned for more exciting sustainable ag research. And when you eat your next organic lettuce, think of all the flowers, and hardworking people, and hoverflies, that it took to produce it!
 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

eOrganic 9845

Video: A Biological Control Buffet in the Salad Bowl of America

mer, 2019/07/10 - 12:14

eOrganic author:

Eric Brennan, USDA Agricultural Research Service, Salinas, CA

Watch this video at https://www.youtube.com/watch?v=zLvJLHERYJI

A natural all-you-can-eat buffet keeps beneficial organisms working on the farm year-round. Hedgerows, cover crops, and insectary plants provide this biodiversity which helps farmers control pests without pesticides and makes the farm more sustainable and beautiful. This fun video by USDA-ARS scientist Dr. Eric Brennan explains how this works at the Agricultural Research Service's organic farm in Salinas, California in high-value production systems for vegetables and strawberries. It provides some details on drought-tolerant, native perennial hedgerows for California and describes some challenges and novel strategies to make intercropping vegetables with a common insectary plant (alyssum) more efficient.

See also another video by Eric Brennan: Efficient Intercropping for Biological Control of Aphids in Transplanted Organic Lettuce

Video Transcript

Hedgerow Control. This is Hoverfly 742, maintaining 2000. Heading 180. Requesting land clearance. Hoverfly 742 turn left. Heading 090. Descend to 1000 until established on the ILS runway. Coyote Brush 32 approach. Cleared to land. Hoverfly 742. Turning left. Heading 090. Descend to 1000 until established on the ILS runway. Coyote Brush 32 approach. Cleared to land.
MUSIC

So you've probably figured out by now that I'm not your typical air traffic controller. I don't direct airplanes in and out of airports, but you might think of me as an organic air traffic controller or a biological air traffic controller. What I mean is that, as I've managed the airspace above this organic farm since 2001, I've tried to encourage a diversity of beneficial organisms to come here to help us to control our pests. And the three main components of our farm that help with this are hedgerows on the farm edges, cover crops that we usually grow when our fields don't have cash crops, and insectary plants that we interplant with our vegetables and strawberries. I like to think of these three components as providing a buffet of food options for beneficial organisms on our farm.

Over the next few minutes I'll give you a short tour of our 22 acres of high value land and explain how our conservation biological control program here works to control pests as we conduct and share cutting-edge, commercial-scale research on organic vegetable and strawberry production. I'm fortunate to have great collaborators here with lots of practical farming experience and a passion to think out of the box and develop new and creative sustainable farming strategies that apply to organic and conventional systems.

To help you understand our farm let's fly up to get a bird's eye view. The cool Pacific Ocean is about 15 miles that way as Salinas Valley opens to Monterey Bay. Our organic farm is connected to about another 150 acres of conventional USDA research land. A simple way to understand the layout of our organic farm is to divide it into four main sections that include strawberries in one section each year, and vegetables and cover crops in the other sections. For example, this section had broccoli this last summer and was just planted to strawberries. Our new strawberry planting also includes a novel cover-cropping strategy in the furrows.

Okay, so let me now provide a few details about these three critical biological control components starting with my favorite place on the farm, the hedgerow. In some ways it reminds me of the biologically diverse tropical forests in Papua New Guinea where I grew up, and which surrounded many of the agricultural fields there. Our hedgerow is a fun place to explore that's filled with biodiversity and is just a relaxing place to take a break when you need one. I consider it a sacred place, because it reminds us of the balanced natural ecosystem that once dominated this landscape and that has so much to teach us to help us to improve our agricultural systems. The hedgerow is essentially the supporting backbone of our biological control system. What I mean by supporting backbone is that the hedgerow is the most stable, complex, and permanent part of our farm. And it's a refuge for beneficial organisms when we disturb our fields with intense tillage between crops. The hedgerows are then the major source of beneficial insects to recolonize our new plantings.

I remember the fun and productive day that our hedgerow was planted in 2003 with the help of volunteers and our local hedgerow guru, my friend Sam. Since then, our hedgerow has been low-maintenance because it includes a diversity of drought tolerant, native perennials, which were irrigated only during the first year. Now a key benefit of the hedgerow and the adjacent berm with flowering annuals is that the diversity of plants ensures that there's always something flowering to provide beneficial insects like hoverflies with the pollen and the nectar that they need to reproduce and thrive. For example, the coyote brush plant where Hoverfly 742 landed—it flowers in the fall and the winter when there are few other sources of food for adult hoverflies on our farm.

Now there are some challenges with hedgerows. For example, some people think that hedgerows increase the risk of food safety problems from rodents, and try to minimize this with fences and toxic baits along the borders with neighboring hedgerows. But I've not seen any compelling scientific evidence to support this concern about food safety. In fact, recent research suggests that removing non-crop vegetation, like hedgerows, may actually increase food safety pathogens. Now one clear challenge with hedgerows is from leaf-eating birds like the White-crowned Sparrow. They like to overwinter in the hedgerows and eat leaves of some crops right next to the hedgerow. Ironically, these same birds may actually help us though, because they can also eat weed foliage under the canopy of some of our cover crops.

Speaking of cover crops, let's now consider their role in biological control on our farm. We grow lots of cover crops in rotation with our vegetables and strawberries and have seen huge benefits. This bumper sticker is one that I designed a few years ago, and it does a pretty good job of summarizing some of the benefits of cover crops in terms of their ability to reduce runoff and improve soil quality, and boost crop yields with fewer fertilizer inputs. But it doesn't say anything about cover crop benefits for biological control. So here's another bumper sticker I just designed to help clarify this. It's got a few common beneficial insects that I often see in our cover crops. I've also seen other beneficial organisms like gopher snakes. Now just like the cover crop provides the gopher snake with a good habitat to hunt for gophers, the cover crop also provides beneficial insects with a source of insects to eat—like aphid species that are usually different from the aphids that are on our cash crops.

Flowering weeds in our cover crops can also provide pollen and nectar for adult hoverflies and parasitic wasps. But the problem with many of these weeds is that they produce seeds quickly, and therefore can increase the hand weeding costs in our subsequent cash crops. So we carefully manage our cover crops to suppress weed growth and flowering. Although wild radish is one weed that we really don't mind in our winter cover crops, because it doesn't flower until late in the spring when the cover crops are usually ready to be mowed down and incorporated back into the soil.

Allright, now for the last part of our biological control buffet, the insectary plants. There are many different types of insectary plants in our region, but I'll just briefly describe two ways that my research has improved the efficiency of using one popular insectary plant, sweet alyssum. First, I'll describe it for transplanted lettuce and then also for direct-seeded lettuce. Alyssum flowers are a great source of pollen and nectar for adult hoverflies, and encourages them to move through lettuce fields. In the process, the female hoverflies lay eggs on lettuce that has aphids. And the larvae that hatch from these eggs eat the aphids, live! When I started working with transplanted lettuce in 2004, farmers here usually gave up about 5 to 10% of their field to grow alyssum in strips or as randomly scattered plants through the field. But I found that a far more land-efficient approach to get plenty of alyssum flowers into the field was simply to insert alyssum transplants between the regularly spaced lettuce, without displacing any lettuce. In other words, you don't need to give up space for alyssum. We call this additive intercropping.

The last method I'll describe is a simple, efficient, and novel way that I've been working on to help farmers plant alyssum seeds with the same precision seeder that they use to plant pelleted lettuce seed. These seeders provide very uniform and regular spacing of the pelleted seed. To achieve this, I teamed up with a local seed treatment company that was able to pellet the alyssum seed to the same size as a pelleted lettuce seed. This was a complicated process because the alyssum seed is much smaller than lettuce seed and therefore the alyssum seed had to be coated in much more pelleting material than the lettuce seed. But it's worked beautifully! And it means that farmers here can now mix just a few teaspoons of pelleted sweet alyssum into their pelleted lettuce seed, and the alyssum will be scattered randomly through the field. The lettuce thinning and weeding crews are then trained to easily identify alyssum seedlings and leave these to flower for the hoverflies. It's a great system!

That's our biological control buffet here at the USDA organic research farm in the Salad Bowl of America—Salinas, California. Our system isn't perfect but we're pretty happy with it. We're always trying to fine tune it—make it a little bit better, more efficient. So I hope you'll stay tuned as we do that. And I also hope that you can find ways that you can support farmers that are using the types of techniques that I described here today.

You know what.... I got to get back up there to hedgerow control tower because Hoverfly 742 that landed on this Coyote Brush plant right here has already fueled up with pollen and nectar and is ready to take off on another mission out there to look for aphids. So I don't want to delay her. I want to encourage her, and I want to keep her safe.

Hedgerow Control. This is Hoverfly 742. Requesting take off clearance. Roger, Hoverfly 742. You are cleared for takeoff!

MUSIC (Fly me to the moon)
 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video: Calculating Paddock Size on Organic Dairy Pastures

mer, 2019/07/03 - 14:51

eOrganic authors:

Sarah Flack, Sarah Flack Consulting

Amanda Gervais, University of Vermont Extension

Introduction

In this video, offered by the eOrganic Dairy Team, grazing and organic certification expert Sarah Flack demonstrates how to calculate paddock size and stocking rates for pastures an organic dairy farm. 

Watch the video clip at https://www.youtube.com/watch?v=NhpxvoHwy8A

Audio Text

My name is Sarah Flack and I'm a grazing consultant. I also do organic farm inspections. Today, we are going to quickly run through how you can figure out how large your paddock needs to be to feed a herd of animals for a day. Then you can go on and do some stocking rate calculations to figure out how many total acres of pasture you need in order to provide the amount of dry matter from pasture to your animals that meets your farm goals.

Let's use an example here. We'll assume that it is a herd of dairy cows and there are 50 in the herd. This farmer's goal is to provide 30 pounds of dry matter per cow from the pasture per day. So this is a farm that's providing the majority of the dry matter from pasture. They're supplementing just a little bit of grain in the barn.

The first thing we need to do is determine what the total dry matter requirement is of the herd for a whole day. So I'll use my calculator--I'll take the 50 animals times the 30 pounds. I come up with 1500 pounds of dry matter per day. That's the requirement of that whole 50 cow herd from pasture.

Now that we've used the grazing stick, and have gone around the pasture and measured how much available grazeable dry matter is available in a whole acre, we came up with 1200 in our example. The next thing we are going to do is divide the 1200 into the 1500 and so we get 1.25. An acre-and-a-quarter is how much you need in order to provide the 1500 pounds of dry matter.

That means for every 24 hours, if you are using 24 hour paddocks that you are putting your animals in, each paddock would need to be an acre-and-a-quarter in size. So each paddock is providing the 1500 pounds of dry matter to the whole herd for that day. And you can go on later with those numbers once you know how long it's going to take each of your paddocks to grow back up to the full pre-grazing height -- in this case to about 8 or 9 inches of height. You can figure out how many total acres that you'll need to graze the whole herd now that you know how much it will take to feed them for 24 hours.

So now that we know that the herd needs an acre-and-a-quarter to feed them for 24 hours, let's figure out how many total acres are needed to feed that herd at different times of the year.

In the spring when the grass is growing very rapidly, it's going to take about 18 days for the pasture to grow back up to the correct pre-grazing height (in this case, the farmer's goal is to graze it when it is about 8-9 inches tall). So we take the 18 days and multiple it by 1.25 (an acre-and-a-quarter), and now we know that the farmer needs 22.5 acres in the spring to rotate throughout that's giving the cows a fresh paddock every day that is an acre-and-a-quarter in size.

Now later in the summer, when the speed that these plants out here in the pasture are growing at slows down, you'll need to add more acres in the rotation. So when you bring the cows back to the paddock, it's always at the correct pre-grazing height. This farmer's goal for the pre-grazing height is about 8 to 9 inches of grass and clover height when the cows come back into each paddock. Now, instead of taking 18 days for the plants to grow back, it's going to take more like 28 to 30 days in the middle part of the summer. On some farms, that will be significantly longer than that, so you need to use the numbers that are appropriate for your own area. Assuming the farmer is putting the livestock into this acre-and-a-quarter paddock every day and it is a 30 day regrowth period, we take the 1.25 and multiply it by 30. The farmer now needs 37.5 acres to rotate throughout to provide the same amount of dry matter intake to the cows.

You can see the farm has gone from needing 22.5 acres in the spring to 37.5 acres during the summer. There may be times in the summer where the regrowth periods are even slower than that and you would need even more acres. But this is a way to give you some ballpark numbers of how many acres you need at the different times of the year for this particular 50 cow herd.

Additional Resources

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video: Identifying Syrphid Fly Larvae: Important Beneficial Insects in Controlling Aphids

mer, 2019/07/03 - 14:41

eOrganic author:

Carmen Blubaugh, Washington State University

This eOrganic video was created by members of a project of the USDA National Institute of Food and Agriculture, Organic Agriculture Research and Extension Initiative (NIFA OREI) entitled Biodiversity and Natural Pest Suppression (BAN-PestS). 

Watch this video clip at https://www.youtube.com/watch?v=N-g-1Qyrk2I

 

Video Transcript

Syrphid flies, also known as hover flies, are beneficial insects. The adult fly lays its eggs on leaves near aphid colonies. As adults, they are important pollinators feeding on a wide range of flowers. In their larval stage, they prey on aphids. Each larva that hatches can consume hundreds of aphids. Syrphid fly larvae are aggressive aphid predators. They are commonly considered to be the most important aphid predator in vegetable crops.

Identifying Syrphid Flies

There are many species of syrphids. The adult flies are usually yellow and black and thus resemble bees. However, like other flies, they only have one set of wings. As their namesake indicates, they can often be seen hovering above flowers or aphid colonies. The eggs resemble a grain of rice and are often laid singly on leaves.

The larvae are frequently confused with common caterpillar pests that feed on vegetable crops. Being able to distinguish between the caterpillar pest and the beneficial syrphid fly larvae is crucial as you make decisions about pest management on your farm. Luckily, there are a few simple features that will allow you to distinguish between syrphid fly larvae and caterpillars. The first thing to look for is whether or not the insect has legs. Syrphid fly larvae do not have legs and move in an undulating manner. Caterpillars have legs. If you are unsure if an insect has legs, try getting the insect to move. The legs will be apparent on a moving caterpillar.

Syrphid fly larvae have nondescript heads, no eyes, and no chewing mouthparts. Caterpillar pests have distinguishable heads with chewing mouthparts. Impressively, these blind legless syrphid fly larvae manage to consume entire aphid colonies. These are valuable creatures to respect and support on your farm.

Promoting Syrphid Flies on Your Farm

You can make your farm more hospitable for syrphid flies by planting flowers that provide nectar for adult flies, such as sweet alyssum. Studies in apple orchards and collards have shown that planting sweet alyssum greatly increased the population of syrphid flies, leading to reduced aphid infestations (Gontijo, Beers, & Snyder, 2013; Ribeiro & Gontijo, 2017). Research out of California has looked at how to most efficiently intercrop sweet alyssum to attract aphid predators to lettuce fields. Their work indicates that as few as 1 to 2 alyssum transplants per 50 lettuce transplants is sufficient (Brennan, 2015). 

Syrphid flies are an important aphid predator and pollinator to promote on your farm. Knowing a few identifying characteristics—no legs, eyes or chewing mouth parts—can help you distinguish these beneficial insects from caterpillar pests. Being able to identify these insects will assist you in making pest management decisions that support these important predators and pollinators.

Follow this link to find a user-friendly flier that will help you distinguish between specific syrphid species. https://calcorenetwork.sites.ucsc.edu/wp-content/uploads/sites/249/2015/10/SYRPHID-FLYER.pdf

References and Citations

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video: Scouting Vegetable Crops: An Introduction for Farmers

mer, 2019/07/03 - 14:35

eOrganic author:

Carmen Blubaugh, Washington State University

This eOrganic video on scouting vegetable crops was created by members of a project of the USDA National Institute of Food and Agriculture, Organic Agriculture Research and Extension Initiative (NIFA OREI) entitled Biodiversity and Natural Pest Suppression (BAN-PestS). 

Watch this video clip at https://www.youtube.com/watch?v=IkixPtTTXyA

Video Transcript Introduction

What was the last crop you lost to a pest? When did you realize you had a problem? Many times we don’t know there is a problem until we are up close and personal with a crop. All too often that is at harvest.

Scouting is the routine monitoring of pest pressure in a crop. A scouting routine can help you identify problems in your field before they get out of control. In this video we will scout for cabbage aphid in brassica crops in the Pacific Northwest. However, the scouting principles and tips can apply to any crop or region.

What is Scouting?

Scouting is a systematic way to assess the health of your crop and threat of pest outbreaks without examining every plant. Scouting relies on sampling a subset of the field to collect data you can use to make informed management decisions. Scouting can reduce your inputs and crop losses, saving you money.

There are various tools used in scouting. The tool you will use depends on the crop and pest. Many pests must be trapped to monitor while others, such as cabbage aphid, can be observed on the crop without trapping. In this video we focus on visual observation, but many of the principles of scouting we cover will apply regardless of the scouting tool used.

To begin a scouting routine, start by researching the pests you are likely to observe and the corresponding beneficial insects. This information will help you identify which scouting tools are appropriate and when to begin scouting. Numerous extension resources are available that describe the community of pests associated with a particular crop in your area.

Scouting 101: Before Entering the Field

When you arrive at the field, commit your attention to scouting. Focus is required to capture signs of pests. First, make observations about the entire field. Look for areas that appear stunted or have a color variation. Notice any unique geographic features, such as a depression. These areas may have higher pest pressure. You will want to visit these areas.

Select a path through the field that will allow you to collect a random yet representative sample. One method is to travel through the field in a "w" pattern, selecting plants to sample randomly along that path. Adjust your path through the field to ensure you visit areas you have identified to be at higher risk for pest infestations. Record your path through the field so that on your next visit you can scout a different route. Each scouting trip, you will select a different random sample. On each scouting trip you may want to visit areas you suspect to have growing pest populations in addition to your random sample.

In the Field

When you reach your first sample, assess the plant overall and then start looking at the individual leaves. Look at both young and old leaves, and don’t forget to search both sides of the leaf. You will want to remove a few leaves for closer observation. Now look at any buds, flowers, or fruit. Depending on the potential pest, you may even use your harvest knife to cut open the stalk or unearth the plant so you can see the roots.

Record your observations and a numeric assessment of the pest. For example, a numeric assessment of cabbage aphid pressure is the average number of aphids per leaf. Select three leaves from different parts of the plant and record the number of aphids and aphid predators per leaf. Repeat for ten plants.

You will follow the same procedure each time you scout, but vary your path through the field and which plants you sample. Standardizing your collection method is necessary to accurately track pest pressure over time.

Calculate the average number of aphids and predators per leaf. Reviewing these averages from visit to visit allows you to determine whether or not the pest pressure is increasing, or if beneficial insects are effectively managing the pest. This information will allow you to determine if and when you need to take action to control the pest, in other words, your action threshold.

Your action threshold is the point at which you’ll experience economic loss if control measures are not pursued. Your action threshold depends on the cost of controlling the pest, the effectiveness of your control measure, the value of your particular crop, and the potential for the pest to cause damage that will impact your ability to sell the crop. These factors vary for different crops. For instance, tolerance for aphids may be higher on kale than broccoli since aphids can get into broccoli heads where they are protected from insecticide applications.

Action thresholds also change over time, as markets fluctuate. Ask your local extension educator for help identifying a recently published action threshold for your region and crop. Keep in mind that action thresholds are usually calculated without considering biological control by beneficial insects, and you may want to adjust your action threshold if you observe high rates of natural pest suppression.

Developing your Scouting Routine

Farming is a demanding occupation. To make sure scouting gets done, it is best to make scouting a habit. Tip: For best results, scout twice a week. For instance, you could dedicate lunchtime Tuesday to scouting a few fields. Keeping a bucket of scouting tools easily accessible can help facilitate regular scouting. Must-have scouting tools include a pencil, paper, clipboard, tally counter, and camera.

Pest emergence and growth are each temperature-dependent, and vary with each crop. Check local extension resources to determine approximately when pests in your crop system emerge, and initiate your scouting routine accordingly.

Scouting is an important practice to do on your farm that will definitely pay off. Check out the Pacific Northwest Insect Management Handbook for up-to-date information on crop specific pests. There, you’ll find examples of action thresholds, local emergence times and other resources to help you prepare for and avoid pest outbreaks on your farm.
 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video: Identifying and Scouting for Late Blight on Organic Farms

mer, 2019/07/03 - 14:32

eOrganic author:

Abby Seaman, New York State Integrated Pest Management Program, Cornell University

Watch this video clip at https://www.youtube.com/watch?v=uCzIFVfyNow

Transcript of Video: Identifying and Scouting for Late Blight on Organic Farms

Late blight is a serious plant disease that affects potato and tomato. It can completely destroy crops in as little as two weeks when conditions are favorable for the pathogen. Phytophthora infestans, the organism that causes late blight, is known as a water mold, which gives us a hint that late blight is favored by high humidity and wet leaves. When relative humidity levels exceed 90%, hundreds of thousands of spores are produced on infected plants, which can be carried by air currents to infect nearby fields and gardens. Late blight epidemics can develop and spread very quickly.

One of the first places to scout for late blight is in seed potatoes before planting. Look for sunken, dark lesions on the surface of the tubers. If these lesions are caused by late blight, a shallow cut across the surface of the lesion will reveal a dry, firm, reddish-brown rot. Often, other diseases will invade late blight infected tubers, making it difficult to determine if late blight is present. Submit suspect tubers to your state diagnostic lab and avoid planting seed that appears to be infected. (Find your state diagnostic lab at the National Plant Diagnostic Network: www.npdn.org)

Other places for early season scouting include piles of culled potatoes, potatoes surviving in compost piles, or volunteer potato plants growing from tubers left in the ground the prior season–especially if late blight was present in your area. Cull and volunteer potatoes should be destroyed before green tissue emerges if possible, or scouted for symptoms if it’s not possible to destroy them. When buying tomato transplants, be sure they appear healthy, with no dark spots on the leaves or stem.

When you're scouting a field, it is important to think about where you’re most likely to find early symptoms. The first symptoms are often found where environmental conditions are most favorable for infection–such as low spots and edges near woods where plants tend to stay wet longer. Also think about places in the field where an organic-approved fungicide application may have skipped, like this spot where an aerial application missed near a power line. (Note: If prohibited fungicides were applied the previous year, then the field cannot be used for organic production in the current year. Consult with your certifier/inspector before using any product or input in your certified organic operation, and read the article, Can I Use This Input on My Organic Farm?)

In this field, late blight was first found near the woods, where plants are shaded in the morning, and there is less air movement. Adding to the wet, humid conditions that favor late blight, the irrigation system was leaking at this corner of the field, so the soil was saturated, increasing the relative humidity even more.

Because seed can be the source of disease inoculum in potatoes, the first sign of late blight may be a lesion on the stem that got its start from the infected tuber, and it could occur anywhere in the field. In this case it would make sense to focus early season scouting on the stem and base of the plant.

Inside dense plant canopies is another place late blight might first appear. When scouting, always look inside the canopy where leaves stay wet and relative humidity stays high later in the day. Be sure to scout the bottom of the plant canopy where leaves dry off more slowly. Staking tomatoes can help keep leaves dry, but if plants are very healthy, humidity can stay high inside the dense canopy.

Late blight lesions on leaves tend to have rounded edges, often with a lighter border. The lesions go right across the leaf veins. Tissue in the center of the lesion may be completely dead, and may appear wet and slimy. The pathogen will produce fragile, white growth in the living tissue surrounding the lesion if relative humidity is high. This is where thousands of spores are produced, which can detach from the plant and be carried for miles on air currents. If relative humidity is low, sporulation will not be present. Very new late blight lesions resemble early signs of several other diseases, and suspect leaves should be brought in from the field and held in a plastic bag with a damp paper towel to allow symptoms and spores to develop.

Late blight affects all parts of the plant. On potato and tomato stems, lesions are black, with a greasy appearance. Sporulation often appears on stem lesions rather than at the border as it does on leaves. On tomato fruit, late blight appears as a firm, brown lesion, and spores may also be produced on the lesion itself.

We hope this introduction to scouting for late blight will help you detect infections on your farm as early as possible. Finding it early gives you the best shot at successful management.
 

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Disease Suppression

mer, 2019/07/03 - 14:28

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

 

This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at https://www.youtube.com/watch?v=1SkYQ5g2hcA

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

Disease Suppression

We’re seeing disease suppression, which is something we don’t entirely understand yet. There are many theories about what could be causing this disease resistance. But particularly the last two years, we’ve seen a very small amount of cucumber mosaic virus or pepper mosaic virus, which is a virus which attacks 800 species of plants, both monocots, grasses, and dicots, vegetable plants, and in fact, weeds as well. Our favorite weed, this Malva neglecta, is a place where the virus over-winters.

If I had seen this 10 years ago, I would’ve been scared to death, because cucumber mosaic virus can cause stunting of plants and diminished yield. But here we have this on our older leaves, mostly, and the plants outgrow it and in fact, are extremely vigorous. If we have any more peppers on these plants, you can see that the plants are falling over because there are so many peppers on this plant. And yet, if you look closely throughout all these plants, you see that there’s a small amount of this cucumber mosaic virus within the population of this living mulch field, yet it never seems to get to a point where we see a diminished yield.

So, the possibility is that these plants are kicking in with their immune system and in some way suppressing the cucumber mosaic virus. There are some theories that plants are encouraged to kick in their immune systems with microbial interactions, with soil microbe interactions, that may be enhanced by organic matter and organic residue additions which is what we think is going on here, but its still a new area and we’re not entirely sure.


 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Nitrogen

mer, 2019/07/03 - 14:26

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at https://www.youtube.com/watch?v=WYe6j0qC1D4

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

Nitrogen

When I first started farming and working with other organic farmers twenty years ago, one of our greatest challenges was getting nitrogen, particularly nitrate-nitrogen to our crop so that we would have early crops. What organic farmers have always faced is a microbially-controlled nutrient release and thus availability to the crop so we tended to be a little slower. What I found working in this system, is that the challenge disappeared after about five or six years of the living mulch creating a recycled nutrient foundation.

So that here in Montana, where it's an even greater challenge than anywhere else I’ve farmed, to make sure that nutrients are available to the crop early enough, we’re getting the earliest tomatoes and red peppers, and in fact green bell peppers at the market than any of the other growers, including the conventional growers. One of the reasons is plants start growing very rapidly because the nutrients, particularly nitrogen, seems to be quite readily available. One of the things that helps this system is the black plastic. I don’t think in this climate, we could do this living mulch system with warm season crops without the heat increase that we get from the black plastic.

Another interesting thing I’ve noticed as a result of this constant addition of residues developing a foundation for a nutrient base is that we don’t have surges of nitrogen the way I used to when I would add a lot of compost or a green manure only in the spring, and till it under and it would be released and then we might side-dress later. What we found is increased crop quality and lasting ability. Peppers, for example, have very thick walls. They get less sun scald problems and we can do our specialty, which is red peppers, without losing as many. We don’t have as much wrinkling and again the breakdown issues that occur with high heat and sun. I suspect that the reason is that we’re seeing lower tissue nitrate-nitrogen. We’re also seeing higher levels of calcium in the tissue; that could also be a reason. But, I suspect it all boils down to the slow release nutrients that we’re maintaining within the system.

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Soil Fertility

mer, 2019/07/03 - 14:24

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

 

This is a Weed 'Em and Reap Part 2 video clip.

Watch video clip at https://www.youtube.com/watch?v=nQ-eXqe8KSs

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT.  

Audio Text

Soil Fertility

One of the exciting things that we’ve learned in exploring this living mulch system is number one: the nutrient balance that we’re seeing and number two: the side benefits of all of the organic residue addition over the last eleven years. We’ve found that this organic residue, even these legumes, that of course are nitrogen-fixing, that we add to the soil doesn’t necessarily provide nutrients immediately. When we mow like this, when we do the continuous residue application throughout the growing season, what we’re doing is building up a foundation of soil fertility that then releases slowly. So this residue that I’m mowing here, may be the nutrients for my crop next year.

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Habitat for Beneficials

mer, 2019/07/03 - 14:21

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

 

This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at https://www.youtube.com/watch?v=8pAVVcUxlzs

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

Habitat for Beneficials

After quite a bit of study in 1995 and ’96, we found that because the living mulch has very close proximity to the crop, in other words, for every row of crop, there is a row of living mulch, we don’t diminish the beneficial or the pollinator insect populations when we mow. Also, as crops finish, like this broccoli here, we let it go to flower and seed and it provides more habitat for beneficial insects. And remember, one of the things that we’ve found is that it’s not just the flowering, the pollen and nectar source, that our parasitic wasps, and our syrphid flies and many of our other predator and parasites need. They also need the cover and even mowing maintains quite a bit of cover. One of the predators that needs this cover the most is ground beetles, carabid beetles. Also spiders require this cover. We found significant increases in the population of those kinds of predators by doing this mowing and leaving the residue on the surface.
 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Weed Ecology

mer, 2019/07/03 - 14:15

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

 

This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at https://www.youtube.com/watch?v=1mafdoKVA_Q

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

Weed Ecology

We’ve learned some stories about weed ecology as well. One of the weeds that has evolved, or at least been released from competition is this Malva neglecta or common mallow. It has basically formed a strong, dominant part of the vegetative system along with chickweed and all of the annual weeds that we had when we began; lamb’s quarters, redroot pigweed, quackgrass, have all disappeared or have been very much marginalized compared to these two weeds. There was a time when I was quite concerned about it, because it’s become very dominant as you can perhaps see here. I just happened to look up in Bob Parnes’ Fertile Soil what actually the nutrient value of this particular weed is. And according to Parnes, mallows contribute 80 lbs of nitrogen per ton, which is actually higher than what legume hay will contribute. So, what’s going on here is obviously, this is not a nitrogen fixer as the clovers are or as the legumes are, so how come there’s so much nitrogen? Basically what has been suggested is this plant is a very good scavenger, a very good accumulator of nitrogen and that it helps cycle it through the system and because I’m creating, over the last eleven years here, a system based on recycled nutrients, we’ve created perfect habitat for this scavenger.
 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Cover Crops

mer, 2019/07/03 - 14:13

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

 

This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at https://www.youtube.com/watch?v=n3s-i1R1laY

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

Cover Crops

The species of cover crops that I’ve used in my system are mainly legumes, mainly clovers. We’ve used Dutch white clover, Alsike clover, red clover, crimson clover, an annual clover called Berseem clover. I’ve also used a number of Australian medics, mainly because they’re drought resistant and they don’t require as much overhead irrigation to get them established. I’ve used snail medic and Parabinga medic. The seed has become somewhat expensive so I haven’t used those in the last few years.

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Mowing

mer, 2019/07/03 - 14:12

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

 

This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at https://www.youtube.com/watch?v=xWsn18WaM2U

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

Mowing is one of the major tasks on this farm. It’s important not only for weed management, but also for soil fertility maintenance. The most important weed component is that mowing will diminish any of the annual weeds, because we basically chop them off before they go to seed. In terms of soil fertility, what’s different about this system is that instead of growing a large amount of biomass and then tilling it in or mowing it down all at once, I do it periodically over the season. The reason that is, is we’re trying to mimic a natural prairie system, much like what would be growing around here and is growing around here in terms of the native vegetation. There, we don’t get one mass of organic residue addition all at once that the soil microbes then have to deal with all at once and they feel a little like we do after a big Thanksgiving dinner; a little sluggish and unable to digest it all at once. This way, mimicking a natural system, every three to four weeks, the clover gets to be a foot to two feet, and we often get bloom, and then we mow it down. The microbes have a steady diet to digest over the entire growing season.

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Overview

mer, 2019/07/03 - 14:09

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

 

This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at https://www.youtube.com/watch?v=Jdg5LAuvWY8

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

System Overview

This cover crop I have here is most of my fertility and it’s going to provide the nutrients for next year’s crop. After harvest, we basically come through and mow everything down. In the spring, the compost is applied over the living mulch from the previous year, which is where the crop will go next year. Then I rip it with a modified potato cultivator. Then we make beds with the bed maker and there’s quite a bit of residue in the beds. If you were trying to plant directly into the bed without having the black plastic mulch, it would be very difficult, because there would be so much residue. We try to get the plastic on a couple of weeks before I transplant so that residue has a chance to break down within the bed. The clover recruits from last year and the newly-seeded living mulch start to come up. So about the time the transplants are eight to ten inches tall, we’re already getting cover. We try to make sure that soil is bare or uncovered for less than three to four weeks every year. Then the plants start to grow, we continue to irrigate the cover crop and drip irrigate the crop and there’s constant mowing of the residue.

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Composting

mer, 2019/07/03 - 14:06

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 17 Dec 2008).

This is a Weed 'Em and Reap Part 2 video clip.

Watch this video clip at https://www.youtube.com/watch?v=Ajg-z7JONIw&list=PL8BA51CA166A839E9

Featuring  

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

Composting

This is the composting operation. I don’t use as much compost as I did eleven years ago. I’ve slowly decreased the amounts, so that we use about two tons per acre now, sometimes less. The way I make the compost is to add green succulent legumes, like this red clover, with straw bedding and sheep manure. Sometimes I’ll add other things, crop residues, but mainly these are the basic ingredients. I used to chop the clover and add it to the compost, but I have finally learned, after 20 years of composting that it's much easier to plant the clover where I’m going to compost, then keep it watered, put the other ingredients, like the manure and the straw on top of it and then I will be mixing it with the front-end loader. After the initial mixing of the compost ingredients, this pile will be turned many more times. But with this initial turning, I’ve mixed the manure, sheep manure, the bedding straw, the green succulent clover and I’ve gotten soil from underneath or associated with the clover root. But also this soil is where the compost was made last year. I’m adding a portion of composted material and a portion of regular soil to help balance the water relations within the compost pile.

 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Nitrogen, Microbes, Roots: Breeding Corn for Nitrogen Efficiency and Fixation

lun, 2019/07/01 - 18:26

This presentation was recorded live at the 2019 Organic Grain Conference, organized by the Land Connection with funding from NIFA OREI. Dr. Walter Goldstein of the Mandaamin Institute discusses his work on breeding corn with high protein quality and N efficiency/Nitrogen (N2) fixation, and ongoing efforts to test the hybrids on organic farms. The basis for N efficiency and protein quality in the Mandaamin Institute cultivars appear to be due to shifts in root efficiency, microbial relationships,  metabolism. These are probably based on the corn plant’s responses to reducing fertilization, including fostering beneficial plant/microbial partnerships. Results indicate the potential and importance of breeding under biodynamic-organic conditions and utilizing ‘emergent’ evolution processes that occurred under N-limited, biodynamic-organic conditions.

The Organic Grain Conference 2019 theme was theme was “Exploring advancements and issues in organic grain farming, together.” Over 30 presenters and panelists delivered sessions on organic grain production, marketing, transition, certification, and emerging research. Twenty-two companies gathered at the trade show, and over 185 farmers, researchers, educators, and industry members attended.

Download the 2019 conference proceedings at https://thelandconnection.org/wp-content/uploads/2019/05/OGC_2019_Conference_Proceedings.pdf

The conference program is available at https://thelandconnection.org/wp-content/uploads/2019/05/OGC_2019_Program_0.pdf

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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Video Clip: Weed Em and Reap Part 2. Living Mulch System: Introduction

mer, 2019/06/26 - 18:56

Source:

Weed 'Em and Reap Part 2: Reduced tillage strategies for vegetable cropping systems [DVD]. A. Stone. 2006. Oregon State University Dept. of Horticulture. Corvallis, Oregon. Available at: http://www.weedemandreap.org (verified 18 Mar 2010).

 

This is a Weed 'Em and Reap Part 2 video clip.

Watch video clip at https://www.youtube.com/watch?v=zis8Hb-VDTo&list=PL8BA51CA166A839E9&index=1

Featuring

Helen Atthowe, BioDesign Farm. Stevensville, MT. 

Audio Text

I’m Helen Atthowe, BioDesign Farm, Stevensville, Montana. The field that we’re in was in hay for about 30 years, and then about eleven years ago, I started doing vegetable production. I had started in Masanobu Fukuoka's approach to minimum till, do-nothing kind of farming. Obviously, Montana was a bit more of a challenge than Japan. So what we’ve done here is tried to mimic the natural systems in Montana with quite a bit more water. We’re doing minimum till, we’re doing living mulches in between the crops so that our residue application is constant, rather than all at once in the spring.

The main crops on this farm are solanaceous crops. Basically we don’t have to market at all because solanaceous crops are hard to grow in Montana. That’s the reason I do it. Eggplants, tomatoes, green and red bell peppers are the main crops here. We throw a little broccoli in, so that we can grow something besides solanaceous crops but mainly, this farm grows solanaceous crops. We sell at Missoula Farmer’s Market and wholesale to local supermarkets in Missoula as well.

The way that I’ve designed this system is minimum labor, so I’m keeping it very small. You can see that I have very wide rows. That’s so I can get my equipment in here and mow. I do very little hand labor. We don’t weed at all. When I say “we” that’s kind of a misnomer. I don’t have as many tasks to do, and so I can run the place myself.


 

This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.

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