Effect of eradicative activity of strobilurin fungicides and difenconazole on mycelium and sporulation of Venturia inaequalis

Abstract

The eradicative effect of two strobilurin fungicides (kresoxim-methyl and trifloxystrobin) and difenoconazole on activity of apple scab spots was studied in greenhouse and field conditions. The reaction of mycelium and sporulation of Venturia inaequalis after fungicides applications were observed in light and scanning electron microscope. Mixture of strobilurin fungicide and difenoconazole applied twice, in 5 days interval, gave the best eradicative effect. The inhibition of sporulation was long lasting and it was observed even 3 and 5 weeks after treatments. The conidiophores, conidia and mycelium were damaged. Also difenoconazole showed good eradicative activity, in field condition up to 5 weeks after application. Trifloxystrobin significantly reduced the number of active scab lesions and the effect was visible even 3 weeks after treatment. Kresoxim-methyl in both tested doses (0,2 and 0,3 kg/ha) was slightly less effective.

Keywords

• eradicative activity
• kresoxim-methyl
• trifloxystrobin
• difenconazole
• Venturia inaequalis