Effect of Azoxystrobin - A Strobilurin Fungicide Against Late Blight of Potato

摘要

Azoxystrobin - a strobilurin fungicide was tested against Phytophthora infestans against mycelial growth and spore germination. It was also tested for its preventive and post-infection efficacy against late blight of potato. There was a cent per centmycelial inhibition at 1 ppm. Germination was inhibited in zoosporangia at 0.5 and in and zoospores at 0.25 ppm. In comparison, metalaxyl and mancozeb showed complete inhibition of mycelial growth only at a much higher concentration of 7 ppm and zoosporangial and zoospore germination at 1 ppm. Azoxystrobin gave preventive effect against late blight up to 15 days in pot culture and 9 days in field conditions. This fungicide was also able to protect upper leaves when sprayed on lower leaves for a considerable period of time. Azoxystrobin was highly effective when applied one day post-infection and had an adverse effect on sporulation when applied 1, 2 and 3 days post-infection.