Underseeding Clover in Organic Wheat to Reduce Mycotoxins and Improve Grain Quality

Underseeding Clover in Organic Wheat to Reduce Mycotoxins and Improve Grain Quality

Summary

This partnership project investigated the practice of underseeding clover in winter wheat and its possible implications for affecting concentrations of the mycotoxin deoxynivalenol (DON) caused by the disease Fusarium head blight (FHB) in grain, grain protein content, and grain yield, with the underlying goal of reducing farmer’s risks of mycotoxin contamination in organically managed wheat. An on-farm study was conducted in partnership with Tom and Dave Kenyon, who manage an organic grain farm in the Champlain Valley of Vermont. Replicated strip plots were set up in a field of ‘Redeemer’ winter wheat in March 2011. Frost seeded clover treatments included a control of no clover, medium red clover seeded at 12 lbs per acre and Ladino white clover seeded at 10 lbs per acre. In July plots were visually assessed for FHB incidence and severity and harvested for grain and evaluated for grain protein content and DON levels. Weed and clover biomass was also measured just before harvest to assess the impact of underseeding on competition to the wheat crop. Our preliminary results show that the incidence and severity of Fusarium head blight as well as DON mycotoxin concentrations was not consistently different between clover treatments nor the non-clover control. We also found that grain yield and protein were not significantly different between treatments. White clover biomass was significantly higher than the red clover biomass and, as a result, weed biomass was significantly lower in white clover treatment as compared to the red clover and control treatments. DON, though not significantly different, was highest in red clover treatments, though all treatment means were below industry thresholds of 1ppm.

These results indicate that underseeding clover did not help reduce the incidence of FHB nor did it enhance the disease and it also had no affect on yield.

Objectives/Performance Targets

Our primary objective was to test at a field scale if the practice of underseeding clover into wheat would help reduce the incidence of Fusasium head blight by providing a barrier for surface splash of inoculant and, therefore, reduce the severity of mycotoxin concentrations in the grain. In addition, we also evaluated the impact of underseeded clover on grain yield and protein content.

In this study, we found that the incidence and severity of Fusarium head blight as well as DON mycotoxin concentrations was not consistently different between clover treatments nor the non-clover control. We also found that grain yield and protein were not significantly different between treatments. White clover biomass was significantly higher than the red clover biomass and, as a result, weed biomass was significantly lower in white clover treatment as compared to the red clover and control treatments. DON, though not significantly different, was highest in red clover treatments, though all treatment means were below industry thresholds of 1ppm.

Accomplishments/Milestones

• The experiment was designed by Jon Zirkle, UVM graduate student, and on March 27, plots were flagged off into an existing winter wheat field and, with the assistance of cooperating farmer’s Tom and David Kenyon, clover treatments were frost seeded into designated 30 by 100 foot replicated strip plots using a hand broadcast spreader.

  In May, we collected soil samples and set up rain-splash collection traps in each plot to collect splash samples containing suspended Fusarium propagules to then be cultured in the lab. Due to unusually heavy rainfall in May and early June, clover establishment was slow and wheat showed slow growth and signs of nitrogen deficiency. However, as summer progressed, clover nearly overtook the wheat, given the inadequate fertility available to the wheat which kept it short.

  In June and July, we collected rain splash samples during three rainfall events (June 10, June 23, June 25) and counted bleached wheat heads to assess FHB incidence and severity.

  On June 21 we offered an on-farm field day to highlight the project. There were approximately 20 to 25 attendees made up of farmers, agency personnel and college students. We were able to show attendees how well the clover had established, pointing out evidence in the field of Fusarium infection (bleaching), and explain the objectives of the trial. Considerable discussion was centered around the impacts of the heavy rain and visible stunted wheat.

  In July, we collected wheat head samples from each plot and assessed Fusarium head blight symptoms for incidence and severity. Quadrat samples of clover and weed biomass were collected from randomly chosen areas from each plot using hand clippers.

  On July 16, Jon Zirkle worked with Tom Kenyon to harvest the plots. Yields were to be determined for each strip plot by calculating the difference in pre and post weight of the Kenyon’s combine using a portable drive-on truck scale. However, due unusually wet weather, the wheat was much shorter than normal and the clover was relatively tall, making it very difficult to efficiently harvest with the combine. As a result, the truck scales were not sensitive enough to provide reliable measurements for the small amount of differences we got between pre and post harvest weights. Therefore, hand samples of a two meter area of wheat were thus gathered and used to calculate yield. The grain from hand sampling was threshed and cleaned for DON testing and protein analysis.

  The August to October time period was used to conduct lab analysis of the grain for crude protein and DON concentrations and to summarize and analyze data. Preliminary results were shared with the Tom and David Kenyon.

  We plan to present the results at the annual Vermont Grains Conference which will be held in March 2012 in Essex, VT and write a summary article for the winter issue of the Northern Grain Growers Association newsletter.

Impacts and Contributions/Outcomes

This project has been able to enhance other on-going research that we have been conducting regarding underseeded clover in wheat and in increasing our knowledge and understanding of how underseeded clover crops interact with wheat growth, diseases and weeds. The Kenyons were very interested in this project from the onset. They had not used this practice of underseeding much before this project. They did end up rigging a ATV mounted spinner and frost seeded red clover into areas of the field outside of our study area. At the upcoming grain conference in March 2012, we plan to discuss the findings of this project and assess the impact it has had on other grain producers in Vermont and the region.

Collaborators: