Since 2016, soybean farmers have quickly adopted dicamba- and 2,4-D-ready crops in their fight against herbicide-resistant weeds. However, the expanded use of these herbicides during the growing season has led to an increased threat of drift damage for neighboring specialty crop growers. Several high-value crops can be damaged by concentrations of 1/300 the labeled rate or lower. Crops with especially high sensitivity to dicamba and 2,4-D include grapes, tomatoes, and soybeans that are not engineered for dicamba-resistance. Recent legal issues have limited the use of three dicamba products for the 2020 growing season, but 2,4-D and other dicamba products are still in use and will continue to pose a risk in areas with diversified or organic production.
A new fact sheet series is available to help specialty crop growers prepare for and respond to possible dicamba and 2,4-D drift. The series provides tips for being proactive, detailed steps for documenting and responding to damage, and a brief background on why dicamba and 2,4-D have been especially problematic. A Frequently Asked Questions fact sheet highlights various concerns pertinent to specialty crop producers. The series sought input from a variety of crop and herbicide specialists across the United States, as well as state regulatory agencies.
Fact sheets are available online at go.osu.edu/ipm-drift.
Preparing for drift
“Vigilance and communications are the two big things,” says Ohio State weed specialist Doug Doohan, “Knowing who your neighbors are, talking to them about your plans, talking to them about their plans, being aware of who’s doing what on the land and when.”
But who is your neighbor when it comes to drift? Just how far can dicamba drift travel? Most spray droplet drift will move short distances. This type of damage is generally limited to adjacent fields. However, dicamba and 2,4-D are likely to drift as a gas or via a temperature inversion. Temperature inversions can be especially damaging, moving suspended pesticides in a fog-like layer for longer distances.
“There’s all kinds of circumstantial evidence of much greater movement,” says Doohan. “When you’re talking inversions, if an inversion is motivated by a 2-3 mph wind, it could go miles—especially if the conditions persist through the evening.”
Doohan has helped investigate several drift cases and was one of the co-authors for the new fact sheet series. He encourages growers to establish a Standard Operating Procedure to prepare for a drift incident, just as they might for food safety concerns. He also stresses the importance of documenting suspected drift quickly, thoroughly, and repeatedly. The new fact sheet series offers detailed suggestions for these activities.
“If you see something, document it,” he advises. “Use your cell phone. You can always delete unneeded photos later, but you can’t go back in time and get the picture you wish you had taken.”
The new fact sheet series was cowritten by specialists at The Ohio State University and Purdue University, with support from the North Central IPM Center Working Group on Herbicide-Drift Risk Management. The working group organized in the fall of 2019 and plans additional projects in the coming year, including more resources and an anonymous survey of specialty crop growers to better assess the extent and frequency of drift damage throughout the north central region. The North Central IPM Center serves Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin and is supported by the USDA National Institute of Food and Agriculture through agreement 2018-70006-28884.
Biostimulants are not exclusive to organic systems, but they are a common input for organic growers. Ohio State vegetable production specialist Matt Kleinhenz has spent many years studying microbial-based biostimulants (MBBS). Few agricultural input markets have seen the kind of explosive growth that has occurred with MBBS.
“These products are widely available, relatively inexpensive, are said to offer interesting and appealing benefits, and rarely put users at significant risk, unlike some other products,” says Kleinhenz.
Nicole Wright, program coordinator for the Vegetable Production Lab’s MBBS project, also attributes market growth to increased interest in microbiology.
“I think growers are applying them and thinking about soil and soil microbiology,” she says, “They are thinking ‘everything I hear says that having healthy soil means having lots of living things in them and if I can contribute to that, it’s a good thing.’”
With a constant stream of products entering and exiting the market, Kleinhenz and his team are less interested in testing specific products and more interested in answering the bigger questions surrounding this subset of agricultural inputs. Their research has focused on identifying which factors are important to product efficacy, such as the effect of timing and application rate.
Kleinhenz and Wright have this advice for growers interested in or already using MBBSs on their crops:
- Do background research. Just because a product is OMRI-listed does not mean it’s been found effective. Set aside time to read up on the product. Take a critical look at label instructions. What details are provided about the timing, application rate and application methods? What can the manufacturer tell you about mixing it with other products or using it in specific conditions or crops?
- Be wary of claims that seem exaggerated. Most of these products create modest, gradual, and/or inconsistent yield improvements. Growers should have realistic expectations for MBBS products.
- Product consistency can be an issue with MBBSs. If a product only works some of the time, the cause may be related to the user, the manufacturing process and product itself, or production conditions. For example, environmental factors like soil fertility, pH, or cropping history might influence the product’s effectiveness.
- Use storage and handling procedures that acknowledge these are living products. Avoid temperature extremes and chlorinated water, for example.
- Track what happens. Referrals from other users of the product are valuable. But remember that their success won’t necessarily be repeated in your farm’s unique conditions. When trying a new product or practice, maintain a similar untreated part of your field to compare. Do your own experiments with rate and timing. Keep records on what you applied, where, and take notes on any differences you see in growth, yield, quality, etc.
- Use good cultural processes to increase microbials in your soil too. Wright likens MBBS products to taking a vitamin vs. eating healthy foods. Cultural practices that favor soil biodiversity, organic matter, and good drainage are also needed to provide food and conditions that allow microbial life to thrive.
Change is coming
So far, these products are largely unregulated. For the first time, the current farm bill includes language defining a biostimulant--an important first step in creating better uniformity in the industry, says Kleinhenz. Some manufacturers are concerned about the overall image of MBBS products and are pushing for a more narrow definition along with efficacy testing.
Kleinhenz feels regulation will usher in increased product consistency and better information for consumers, but regulation may also limit the number of products available. Testing product efficacy requires time, expertise, and/or expenses that smaller manufacturers may find challenging.
He also questions if it is truly appropriate to apply the same efficacy standards used for many mainstream agricultural inputs. Based on averages and standard, proven statistical analysis, a comparison of treated and non-treated plots failed to show that inoculation (product use) significantly influenced yield. However, the Vegetable Production Systems Lab team observed many times when a MBBS did increase yield (and a few times when it lowered it).
“If you went out to your truck and it only started half of the mornings, you’d be pretty annoyed and conclude it’s unreliable, that it’s not working,” Kleinhenz says. “However, if you apply a product to your crops or soils and see measurable improvement say, 30% of the time, you might still find the application worthwhile if the costs and other risks were low. Our goal as a team is to provide growers and others with information they can use to distinguish worthwhile from unwise investments and practices.”
There are many additional practical questions to answer that could involve microbiology and decision-making. For now, Kleinhenz and his lab are enjoying the conversation and questions stimulated by this growing and changing industry.
This research is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, Organic Transitions Program under award Number 2016-51106-25714 and also under award number 2016-38640-25381 through the North Central Region SARE program under subaward number LNC16-380.
It's time again for Ohio's largest sustainable food and farm conference. This year's OEFFA Conference will feature a larger trade show area, plus three days of workshop sessions and events featuring more than 70 topics and speakers.
Among this year's educational sessions, the Ohio State Vegetable Production Systems Lab will host Do's and Don'ts of Getting More From Microbe-Containing Crop Biostimulants on Friday, February 14 from 12:45-1:45pm. Session leader Matt Kleinhenz invites producers to bring along their lunch and share experiences, concerns, and questions about these commonly used, but often difficult to evaluate, products.
Kleinhenz, an Extension specialist and professor with The Ohio State University’s Department of Horticulture and Crop Science, will lead discussion on the promise and challenge of using microbe-containing crop biostimulants in organic crop production, with an emphasis on vegetable production.
While many organic growers use these types of inputs, the benefits of doing so are rarely clear. Kleinhenz will discuss major reasons for these unclear responses. He will also provide tips for selecting, using, and evaluating biostimulant products effectively. The workshop will integrate hands-on demonstrations and how-to discussions, incorporating news from farms, research stations, and product manufacturers. Participant questions and observations will be blended into discussion on product-crop and product-product compatibility, preparation, application, handling, storage, and normal product effects on crops and yields.
Kleinhenz and his lab have been working with microbe-containing biostimulants for several years, supported by the National Institute of Food and Agriculture USDA Organic Transitions Program and through the North Central Region SARE program. Those unable to attend the OEFFA conference session can read more about Ohio State work with Microbial-based Biostimulants (MBBS) and their Use in Commercial Vegetable Production by visiting the Vegetable Production Systems Laboratory website: https://u.osu.edu/vegprolab/research-areas/vegebiostimsferts/
Kleinhenz is one of 17 Ohio State presenters at this year's OEFFA conference. For more details about the OEFFA conference and schedule, visit www.oeffa.org/conference2020.php. Walk-in registration is available for Friday and Saturday's programming. The Exhibit Hall is open to the public on Thursday from 4:00-7:00 p.m. and Friday from 5:00-6:30. p.m.
Based on an article from Organic Seed Alliance by Kiki Hubbard. Read the full article here.
New varieties of disease-resistant cucurbits are commercially available as a result of Cornell University's Eastern Sustainable Organic Cucurbit Project.
Through participatory efforts with farmers and regional seed companies, Extension researchers developed new varieties with organic producers in mind, focusing on resistance to common diseases and pests, but also on production and culinary characteristics important to organic farmers.
“All of our successes with DMR are owed to farmer input,” says project director Michael Mazourek. “We took moderately resistant material that we had at Cornell, moderately resistant material identified by organic farmers, and people are seeing the literal cross-pollination of these partnerships in DMR varieties now available to growers.”
‘Trifecta’ muskmelon stood out for its excellent eating quality and yield–even under levels of downy mildew pressure that defoliated most commercial melon varieties. The variety also exhibited good bacterial wilt resistance and was less prone to damage from striped cucumber beetles. ‘Trifecta’ is currently available for sale through Common Wealth Seed Growers and Southern Exposure Seed Exchange.
DMR401 cucumber, a downy-mildew resistant (DMR) slicing cucumber variety, now available for purchase through Common Wealth Seed Growers, High Mowing Organic Seeds, SeedWise, and Southern Exposure Seed Exchange.
DMR264 cucumber, excellent resistance to new strain of downy mildew, smaller and bred for warmer climates with severe pressure from downy mildew. Available from Common Wealth Seed Growers.
Additional varieties are being tested for release.
The Eastern Sustainable Organic Cucurbit Project has received funding from the USDA Organic Research and Extension Initiative, as well as the Organic Farming Research Foundation, Sustainable Agriculture Research and Education (SARE), and the Clif Bar Family Foundation. Read more about the project at eOrganic.
Use of compost and a mixed species hay crop are recommended.
For farmers transitioning from a conventional to an organic farming system, decisions made during the three-year transition period can influence important factors of future production, such as soil-borne pathogens, soil fertility, and soil structure. In this study, compost incorporation strongly affected physical, chemical, and biological soil health factors and, overall, the soil food web. Using a mix of perennial hay during the transition was most successful in reducing disease-causing pathogens in the soil. Highest available N and yields occurred in the plots using high tunnel vegetable production.
Materials and Methods
A three-year study was conducted in Wooster, Ohio, to evaluate four common rotational strategies used during transition from a conventional to an organic farming system. The four organic transition strategies evaluated were: 1) tilled fallow, 2) a single planting of mixed species perennial hay, 3) low intensity open field vegetable production, and 4) intensive vegetable production under a high tunnel.
Each transition strategy plot was split in half with 15,000 lbs./ac composted manure applied each year to one half.
At the year of certification, the fields were planted to tomato, with two smaller plots of soybean.
- Compost treatment increased organic matter of soils in all treatments, lowered bulk density, and increased NO3-N, and microbial biomass-N.
- The addition of compost boosted plant vigor for tomatoes for all transition strategies, but had an inconsistent effect on suppression of soil-borne diseases.
- Transition cropping strategy was the main factor influencing bacterial community structure in the soil and the rhizosphere.
- Bacterial communities involved in disease suppression were more abundant in soil previously cropped with hay compared to tilled fallow and low-intensity vegetable production. This was true for both tomato and soybean crops.
- Overall, the mixed hay was the most effective in decreasing damping-off for both tomato and soybean crops.
- Tomato yield during year four was much higher in the high tunnel plot. The hay treatment also showed better yield than the tilled fallow and open field vegetable production.
Why Researchers Think the Hay and High Tunnel Treatments Did Better
Disease suppression might happen in two ways. One involves specific action against pathogen populations. For example, brassicas (cauliflower, kale, turnip, radish, cabbage) suppress soil-borne diseases by exuding sulfur-rich substances that are toxic to many pathogenic soil organisms. And certain species of nematodes eat bacteria and fungi that cause plant diseases. Disease suppression can also occur from high competition for available resources. In both cases, the disease suppression is associated with the overall composition of the microbial community (bacteria, fungi) present in the soil and the rhizosphere.
The hay crop used in this experiment was a combination of Festulolium (a rye fescue hybrid) under-sown with alfalfa, red and white clover, timothy, chicory, orchardgrass, and plantain in equal proportions. Researchers concluded that the above-ground diversity of the hay mix supported an increase in beneficial soil organisms that compete or interfere with pathogens, thus, reducing incidence of disease in future crops.
The highest yields in this study were from the high tunnel plots. While some of the increase resulted from extending the growing season, soil analyses also found a higher level of available N in the high tunnel plots. Researchers think this was a result of maintaining the soil food web in a biologically-active state during the cold early spring months in northern Ohio. The monthly mean soil temperature inside the high tunnels was warmer by 35–41°C from January to May while from July to September it was marginally lower than the outside soil temperature. (Based on top 4 inches.)
For more information on using tunnels in vegetable production, visit the Vegetable Production Systems Laboratory’s Crop Enivronments page.
Prepared by Louceline Fleuridor and Cassandra Brown
Based on summaries of the following papers:
Benítez, MS; Baysal, F.; Rotenberg, D.; Kleinhenz, M.D.; Cardina, J.; Stinner, D.; Miller, S.A.; Gardner, B. B. 2007. Multiple statistical approaches of community fingerprint data reveal bacterial populations associated with general disease suppression arising from the application of different organic field management strategies. Soil Biology and Biochemistry Volume 39, Issue 9, September 2007, Pages 2289-2301
Briar, S.S., Miller, S.A., Stinner, D., Kleinhenz, M.D., & Grewal, P.S. 2011. Effect of different organic transition strategies for peri-urban vegetable production on soil properties, nematode community, and tomato yield. Applied Soil Ecology, 47, pgs 84-91.
Baysal, F; Benitez, MS; Kleinhenz, MD; Miller S.A.; Gardner B.B. 2008. Field management effects on damping-off and early season vigor of crops in a transitional organic cropping system. Phytopathology, Vol. 98, No. 5.