The Effect of Adjuvants, Spray Volume and Nozzle Type on Azoxystrobin Efficacy Against Leptosphaeria Maculans and L. Biglobosa on Winter Oilseed Rape

Abstract

In two vegetative seasons 2005-2006 azoxystrobin (Amistar 250 SC at the dose of 0.7 dm 3 /ha) was applied as a spraying treatment at the beginning of plant flowering against stem canker (Leptosphaeria maculans and L. biglobosa) in winter oilseed rape crops. The effect of the following spray application parameters: water volume (200 and 400 l/ha), adjuvant type (Break Thru S 240 - 0.1% and Atpolan 80 EC - 0.5%), and nozzle type (XR11002 - fine droplet size and DB11002 - coarse droplets at 0.4 MPa pressure) on the fungi- cide efficacy was studied. The results of presented studies indicated that azoxystrobin (Amistar 250 SC) caused a significant decrease of rape infection by stem canker. Addition of adjuvants did not significantly increase the fungicide effectiveness, and sometimes low- ered its action (especially after the application of Atpolan 80 EC). The applied spray volumes of water and nozzle type provided an effective protection of oilseed rape against stem canker, however, in some cases the results of field experiments were not significantly different. The best results of the disease casual agent (L. biglobosa) control, statistically proved were shown at the higher spray volume (400 l/ha), regardless of nozzle type (droplet size) and adjuvant application.