Practical experience with antiresistance strategies in the fungicides control of potato late blight

Abstract

Pathogens with rapid reproductive cycles, producing large number wind-spread dispersed infection propagules like sporangiospores, are more likely to pose problems of resistance than slowly reproducing pathogens, which are dispersed over only short distances. Phytophthora infestans, is highly adaptable pathogen capable of exerting high disease pressure on crop, and develop resistance to phenylamid fungicide methalaxyl in the potato crop in Europe (1981-1984). Metalaxyl was then reintroduced for use in mixtures coformulated with multisite compounds, and the proportion of resistance strains "subpopulations" rose again, and albeit to a level lower than at the outset. The use of metalaxyl on seed crops, with the possibility of resistance being carried over the next season. Current recommendations are to use alternative multiside fungicides on potato crops. Our results illustrate the importance of understanding pathogen epidemiology in the management of fungicide resistance.

Keywords

• chemical control
• phytophthora infestans
• cost/benefits