Use of green manures to reduce inoculum production of Fusarium graminearum on wheat residues

View the project final report

• 2005 annual report
• 2006 annual report

Commodities

• Agronomic: sorghum (milo), wheat

Practices

• Crop Production: conservation tillage
• Pest Management: biological control
• Soil Management: green manures, soil analysis

Fusarium head blight (FHB) is one of the most devastating diseases of wheat and barley. FHB is caused by several species of Fusarium, though F. graminearum is the most important species. Residues of infected cereal crops at the soil surface are recognized as the principal source of inoculum and have contributed to the upsurge of FHB following the adoption of conservation tillage practices. This work will investigate the use of green manures in suppressing F. graminearum in association with crop residues. I propose to determine the effects of green manures on the frequency of soilborne antagonists inhibitory against pathogenic F. graminearum, quantify the impacts of green manures on the survival of F. graminearum on wheat residues, and determine the influence of green manures on the rate of decomposition of wheat residues. Prior research has shown that green manures can significantly influence both, survival of Fusarium in soil and the frequency of Fusarium-inhibitors in the soil microbial community. F. graminearum populations on residue, and the frequency and intensity of its inhibitors in the soil will be monitored over three months following the incorporation of the green manures in both greenhouse and field trials. The inclusion of green manures in the crop sequence may contribute substantially to preserving the viability of conservation tillage practices, meeting one goal of the NCR-SARE broad-based outcomes. In addition to their benefits in disease management, green manures also enhance soil organic matter and nutrients, improve soil structure, and contribute to weed and erosion control. This research will contribute to the development of alternative strategies for managing FHB and for minimizing the risk of severe FHB epidemics.

In the short-term I propose to:

- determine the effects of green manures on the frequency of soilborne antagonists inhibitory against pathogenic F. graminearum, and
- quantify the impacts of green manures on the survival of F. graminearum on wheat residues, and also,
- determine the influences of green manures on the rate of decomposition of wheat residues.

These results will be used to establish the potential for green manures to significantly reduce inoculum production by F. graminearum in wheat fields, and will yield publications in the scientific literature. Results from this work will provide a basis for further studies of the impacts of green manures on Fusarium Head Blight (FHB) on wheat. We will continue to communicate actively with wheat growers during all phases of this research, including through at least 2 field days. We will also continue to work with farmers in identifying production fields for sampling (see methods). In the long-term, this research will contribute to the development of alternative strategies for managing FHB and for minimizing the risk of severe FHB epidemics. In addition, this work can be used as a model to manage F. graminearum in other crops (i.e. barley or corn), and also as a model for other pathosystems in which soilborne antagonists influence the densities and activities of diverse plant pathogens.