Practical Biodiversity: Keeping Oat on Farms by Helping Farmers Enhance Disease Resistance
For the third year, 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. There was adequate rust at three of the Minnesota locations and all four of the Iowa locations. Over the three years, a total of 15 locations have experienced sufficient rust for measurement. Over these locations, rust severity of the blend was significantly lower than the average of pure lines. Over 23 environments tested during three years for yield, the blend significantly outperformed the average of the pure lines, and was equal to the yield of the best pure line.
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.
Our first accomplishment for the third year of this research was to continue the comparison of an oat blend relative its component varieties, ‘Blaze’, ‘Kame’, and ‘Spurs’. Experimental plans were developed 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 locations showing rust to score in late June and early July in Iowa and late July in Minnesota. Rust pressure was higher than in the first two years of the study. In the third year, seven of the eight locations 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 significantly less in the blend (4.5% of the leaf infected) than the average of the three pure lines (7.3% of the leaf infected). Among the component varieties, two have had average severities higher than the blend (‘Kame’ and ‘Blaze’, with average severities of 6.9% and 14.6%, respectively) and one has average severities lower than the blend (‘Spurs’, with average severity of 2.7%). The effect of blending has been to create a variety with a resistance similar to that of a resistant variety. Oat yield has been measured in all environments. Overall, yield was significantly higher in the blend (87.4 bu/ac) than the average of the three pure lines (82.9 bu/ac). The blend yield was not different from that of the highest yielding pure line component, ‘Spurs’ (87.3 bu/ac).
As our second accomplishment, we have continued outreach on this work. A research cooperator meeting was held in Ames, IA the second week of February, 2008. A field day was held at the Verlan and June Van Wyk farm in Sully, IA on June 27, 2008 with an attendance of 24 people.
Impacts and Contributions/Outcomes
As this research draws to a close, its impact is unclear. On the one hand, the research clearly shows an advantage to the specific blend that we evaluated relative to its three pure variety components. On the other hand, we do not know if this would be general phenomenon with any blend, if it would require the careful component selection that we used, or if it is a fluke altogether. Further research in that regard would be required. Further, assuming that we have identified a useful management practice, that practice relies on specific information being available and on farmer know-how to use it. No institutional pipeline has been developed to provide the information on an ongoing basis. While our outreach activities have reached about 100 farmers who are now aware of the possibility of variety blending, we do not know whether their practices have changed.
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