Abstract
The mode of action of the fungicide metalaxyl againstPlasmopara halstedii, the causal agent of sunflower downy mildew, was studied following its application before, during and after artificial contamination of seedlings. The development of the fungus within the treated seedlings was examined microscopically and compared to that occuring in untreated genetically susceptible or resistant genotypes. Hypersensitive-like reactions and necrotic zones leading to the inhibition of fungus growth within the hypocotyl were observed for the three modes of application. This suggests that sunflower defence mechanisms activated by genetical resistance are also involved in the control of downy mildew by metalaxyl.
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Mouzeyar, S., Vear, F. & de Labrouhe, D.T. Microscopical studies of the effect of metalaxyl on the interaction between sunflower,Helianthus annuus L. and downy mildew,Plasmopara halstedii . Eur J Plant Pathol 101, 399–404 (1995). https://doi.org/10.1007/BF01874853
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DOI: https://doi.org/10.1007/BF01874853