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Variation in the response of cashew genotypes to the targeted application of fungicide to flower panicles for control of powdery mildew disease
Author(s) -
Sijaona M. E. R.,
Mansfield J. W.
Publication year - 2001
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1046/j.1365-3059.2001.00560.x
Subject(s) - powdery mildew , fungicide , biology , panicle , inflorescence , horticulture , mildew , disease control , genotype , agronomy , yield (engineering) , microbiology and biotechnology , gene , biochemistry , materials science , metallurgy
Application of the fungicide triadimenol (Bayfidan) directly to inflorescences of cashew was investigated as a means of controlling powdery mildew disease caused by Oidium anacardii. Disease development and nut production were studied in 12 cashew genotypes that differed in their susceptibility to mildew. Panicle colonization by O. anacardii reached 100% coverage in all genotypes without fungicide treatment, but rates of infection differed significantly. Triadimenol sprays reduced mildew to less than 9%, even in panicles of highly susceptible genotypes. In the absence of disease, particularly good yield responses with more than nine times more nuts set than untreated controls were achieved by AM6 and AC1, which were categorized as highly susceptible and intermediate, respectively, in reaction to powdery mildew. By contrast, the partially resistant genotypes AZA2 and AC6 both produced yield response ratios of less than 3·0. The targeted treatment of flower panicles to control mildew is recommended, rather than the current practice of wastefully treating whole trees on which all mature leaves are naturally immune to infection.