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

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

Summary

This study investigated the use of green manures for reducing F. graminearum survival in association with wheat residues in greenhouse and field experiments. Green manures promoted the development of higher densities and Fusarium-antagonistic abilities of F. graminearum-antagonists in soils. The use of green manures did not significantly impact the survival of F. graminearum in wheat residue. However, streptomycete densities and F. graminearum-antagonist densities were significantly positive correlated with reduced survival of Fusarium. These results suggest that the use of green manures can enhance populations of indigenous soil microorganisms antagonistic to the survival of F. graminearum in wheat residue.

Objectives/Performance Targets

• Determine the effects of green manures on the frequency of soilborne antagonists inhibitory against pathogenic F. graminearum, and on the intensity of their F. graminearum inhibition. Quantify the impacts of green manures on the survival of F. graminearum on wheat residues. Evaluate the effects of green manures on the rate of decomposition of F. graminearum-infected residue.

Accomplishments/Milestones

As stated in the previous report, all the data was collected in the previous period and only data analysis was remaining for this second report.

Laboratory work and statistical analyses were completed during this period.

Most relevant results indicate that sorghum-sudangrass and buckwheat green manures generally increased the densities of F. graminearum antagonists relative to fallowed soil, though the differences were not always statistically significant. Among all experiments, the significant negative correlation between F. graminearum antagonist densities and survival of Fusarium on wheat residue suggests that increases in antagonist densities offer potential as a means for controlling FHB. However, the increases in F. graminearum densities following green manure treatments were insufficient for inducing consistent reductions in F. graminearum survival in wheat residue in field and greenhouse trials.

This is the first report demonstrating the potential of soil microbial communities to reduce infestation of wheat residue by F. graminearum. Though a single cycle of green manure was insufficient to significantly impact F. graminearum survival, our results suggest that further investigation on the use of strategies for enhancing soil antagonist populations using green manures are warranted.

Impacts and Contributions/Outcomes

The results support the use of green manures to increase the population of indigenous soil microorganisms with a capacity to antagonize the survival of F. graminearum in wheat residue. A directional selection to increase the indigenous population of biocontrol agents in soil may be achieved by including green manures in the crop sequence. However, since this is the first report using green manures to manage FHB, further investigation is needed before giving an estimation of benefit on the sustainability of wheat growers. Although some adjustments of this approach is required (e.g. adaptation of green manures for late planting dates), we can anticipate that making this technology more effective, a reduction of the risk of severe FHB epidemics is expected, contributing to the sustainability of the production system.

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