Practical Biodiversity: Keeping Oat on Farms by Helping Farmers Enhance Disease Resistance
For the second 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 no rust at the Minnesota locations and fairly light rust at the Iowa locations. Over the two years, a total of eight 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 16 environments tested during two years, blend yield was significantly greater than the average of the pure lines.
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 second 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 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 locations showing rust to score in late June and early July. Each location was sampled twice. Harvest and agronomic data collection proceeded smoothly. As in the first year of the study, rust pressure was not high. As a result, we can only assess the effect of blending under mild rust conditions. In the second year, four of the eight locations, all in Iowa, 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 (0.2% of the leaf infected) than the average of the three pure lines (0.9% of the leaf infected). Obviously, these are very low average severities and over half of the leaves collected showed no symptoms or only a single rust pustule. Among the component varieties, two have proved more resistant (‘Kame’ and ‘Spurs’, with average severities of 0.2% and 0.1%, respectively) and one has proved to be more susceptible (‘Blaze’, with average severity of 2.5%). The effect of blending has essentially been to reduce rust severity in the blend to that of a resistant variety. In the environment with the highest rust severity experienced thus far (averaging 23% of the leaf infected), severities across Blaze, Kame, Spurs, and Blend, respectively, were 49%, 53%, 3%, and 13%. Oat yield has been measured in all environments. Overall, yield was significantly higher in the blend (91 bu/ac) than the average of the three pure lines (86 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, 2007. Rick Exner prepared a two-page handout for the Practical Farmers of Iowa meeting in January 2008. This information was also reproduced in the PFI general research report for 2007.
The foundation that was laid in the first year of this study is starting to bear fruit, as we accumulate data on the effect of this blend. We are glad that we planned for a longer term experiment, and hope (for our sake, not generally) that we will have more severe rust infestations in 2008.
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.
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