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Effect of tillage practice on fusarium head blight of wheat

Miller, J.D., Culley, J., Fraser, K., Hubbard, S., Meloche, F., Ouellet, T., Seaman, W.L., Seifert, K.A., Turkington, K., Voldeng, H.
Canadian journal of plant pathology 1998 v.20 no.1 pp. 95-103
Fusarium graminearum, Zea mays, Glycine max, flowering, no-tillage, blight, crop residues, disease outbreaks, Triticum aestivum, genotype, DNA fingerprinting, incidence, crop rotation, Ontario
Observations in wheat of the effect of tillage practice on incidence of fusarium head blight (FHB) were inconclusive, but ecological data suggested that zero tillage resulted in increased seed infection compared to conventional tillage. The contribution of inoculum from crop debris as a source of Fusarium graminearum in a wheat-corn-soybean rotation under conventional and zero tillage was examined. Disease was established in field plots by inoculating highly susceptible genotypes of wheat at anthesis and corn at silk emergence with strains of F. graminearum that had been characterized by molecular fingerprinting. Crop residue was an important source of inoculum of F. graminearum. In crop residue collected in the spring of the year following inoculation, the introduced strains comprised approximately 90% of the F. graminearum strains isolated. Wheat kernels harvested in the three crop years following the inoculated crop also were examined for infection by fusaria and incidence of the introduced strains of F. graminearum. No effect was found of tillage or rotation on overall disease incidence or kernel infection. However, conventional tillage markedly reduced the level of kernel infection by the introduced strains compared to the no-till plots, especially in the first and third years after inoculation. In no-till plots the two introduced strains comprised 79% of all F. graminearum strains present in kernels harvested in the first season following introduction, 55% in the second, and 46% in the third; in the tilled plots the introduced strains accounted for 20%, 40%, and 13%, respectively, of the kernel infection in the three years. Insects representing six of seven genera most frequently collected in the plots were contaminated by the fusaria present on the plants but there was no evidence that insects spread the disease. Under epidemic conditions, the use of cultivars with tolerance to FHB is more important than tillage practice on epidemics of FHB.