Practical Biodiversity: Keeping Oat on Farms by Helping Farmers Enhance Disease Resistance

Practical Biodiversity: Keeping Oat on Farms by Helping Farmers Enhance Disease Resistance

Summary

Crown rust severity in a blend of three elite oat varieties was compared to the average rust severity of pure stands of the components in large one-acre plots on three farms and an experiment station in both Iowa and Minnesota. The months of May and June were fairly dry in 2006 such that rust pressure was relatively low. In over four locations that experienced rust the severity on the blend was numerically, but not statistically, significantly lower than the average of pure lines. Over all eight locations blend yield was numerically but not significantly greater than the average of the pure lines.

Objectives/Performance Targets

The project will inform both the farmer community and the scientific community in the short term. In the intermediate and longer term, the project has the potential to affect the landscape of the Upper Midwest, the way that producers manage rust in oat (Avena sativa L.) and in other crops, and the paradigms of scientists developing strategies to counter these diseases.

In the short term, this project will 1) determine the extent to which variety mixtures can control oat crown rust, caused by Puccinia coronata Corda, and increase the profitability and stability of the crop; 2) provide the data on the disease resistance specificities of Upper Midwest oat varieties that farmers will need for variety selection; and 3) increase farmer content knowledge and foster communication to and among producers on the value and use of this information.

In the intermediate term, project outreach will 1) provide farmers and seed houses procedural knowledge of how to increase and stabilize oat yield and quality by combining complementary commercial varieties; 2) increase discussion among oat breeders on how to develop varieties with diverse disease resistance specificities; and 3) by improving oat profits, increase the diversity of Upper Midwest cropping systems, enabling longer, environmentally healthier, and more profitable rotations.

In the long term, this project will 1) contribute to highlighting the value and increasing the adoption of within-crop genetic diversity in sustainable farming systems by showing its effectiveness in oat and 2) encourage research on within-crop diversity approaches in other crop/ pest systems.

Accomplishments/Milestones

Our first accomplishment has been to assess the resistance of 19 elite spring oat varieties to some 186 field-collected isolates of the crown rust pathogen, Puccinia coronata Corda. Varieties were rated on a five point scale from highly resistant (HR) to susceptible (S). These ratings were converted to a numerical score allowing the covariance in the resistance specificities of the varieties to be calculated. Sums of these covariances were then computed across all possible three-variety combinations to determine combinations with low covariance sums. We judged these to represent complementary variety combinations. We chose one combination (‘Blaze’, ‘Kame’, and ‘Spurs’) because of its low covariance sum and the adaptation of the varieties to Iowa and Minnesota. These data will be published in the oat newsletter and will also form a component of a peer-reviewed analysis of the experiments funded by SARE.

Our second accomplishment has been to run the first year of the field trials to assess the value of this approach to composing variety blends for the reduction of crown rust disease severity. A research cooperator meeting was held in Ames, IA the second week of February, 2006. Experimental plans were developed there in collaboration with farmer participants. We sourced seed of the varieties and distributed seed to farmer cooperators in Iowa and Minnesota. Field layout and planting plans were developed by farmers with the assistance of Rick Exner in Iowa and Roger Caspers in Minnesota. We sampled leaves from all locations to score for rust in late June and early July. Each location was sampled twice. Harvest and agronomic data collection proceeded smoothly. The weather was relatively dry in May and June in 2006 in Iowa, and in June and July in Minnesota, and thus rust pressure was not high. Four of the eight locations, two in each state, had rust severities high enough that we could evaluate blend effects there. We analyzed data on rust severity in the upper canopy at the second evaluation date, as these data showed the highest severities. Rust severity was numerically, but not statistically, significantly less in the blend (17% of the leaf infected) than the average of the three pure lines (24% of the leaf infected). Oat yield was measured at all eight locations. Yield was numerically, but not significantly, higher in the blend (96 bu/ac) than the average of the three pure lines (89 bu/ac).

Our third accomplishment was to hold two field days, one in each state. The Minnesota field day was organized by Deon Stuthman and cooperator Ted Tews on 19 July 2006. About 15 people, including 2 milling industry reps, attended in spite of the threatening weather. The Iowa field day was organized by Rick Exner and cooperator Roger Lansink on 16 September 2006. Jean-Luc Jannink presented information there on the principles of the experiment to an audience of about 60.

Much was accomplished in this first year. We have laid the foundation for the rest of the experiment, which is set to last for two more years. Data from Year 1 are promising. The trend is for a one third reduction in rust severity and an 8% increase in yield of the blend relative to the average of the pure lines. If we see similar trends in the next two years we will have strong evidence of the value of blending.

Impacts and Contributions/Outcomes

It is as yet too early for this work to have had an impact. The main impact to date is that we, the researchers, remain energized and we believe our cooperators do also. The potential impact of this research comes as much from the benefit it might provide oat growers as from the fact that it will help increase the stability and viability of the oat crop, leading to a more diversified agriculture in the upper Midwest.

Collaborators: