Effect of fungicide application date against Sclerotinia sclerotiorum on yield and greening of winter rape

Abstract

In experiments with winter rape during 2004-2008, we examined the effectiveness of fungicides containing active ingredients based upon triazoles and SBI inhibitors (group A): flusilazole 250 g/l a.i., flusilazole 125 g/l a.i. + carbendazim 250 g/l a.i., and cyproconazole 120 g/l a.i. + carbendazim 300 g/l a.i. Fungicides based upon older and newer triazoles, strobilurins, and SDH inhibitors (group B) were also used: cyproconazole 80g/l a.i. + azoxystrobin 200 g/l a.i., prothioconazole 250 g/l a.i., prothioconazole 125 g/l a.i. + tebuconazole 125 g/l a.i., and boscalid 200 g/l a.i. + dimoxystrobin 200 g/l a.i. The application of group A fungicides against S. sclerotiorum during BBCH 65-69 growth stage had demonstratively higher effectiveness, while for group B the application date had no effect. The greening (or "stay-green") effect only occurred with group B. The correlation coefficient for greening effect and yield was R = -0.3033 for applications during BBCH 61-65 while it was R= -0.3542 for BBCH 65-69 stage, thus indicating a relatively weak relationship.