Management of powdery mildew disease in hazelnut orchards in Sakarya province

Hazelnut (Corylus avellana L.) is the most important agricultural product is grown in Karasu village in Sakarya province. Powdery mildew disease leads to significant crop losses sometimes in the hazelnut orchards. The efficacy of harpin protein %, Lactobacillus acidophilus yeast extract+bonzaic acid, Acibenzolar -S- methyl (A-S-M) and two fungicides were investigated against to powdery mildew in Foşa (Yomra) variety of hazelnut in this study. The plant activators and fungicides were applied to spray six times during the experiment to naturally infected hazelnut trees by powdery mildew. According to the results of the research, L. acidophilus yeast extract + bonzaic acid, A-S-M, and harpin protein were effective in decreasing disease severity by 49,26%, 55,83% and 33,34%, respectively. In fungicide applications, the effects of fluopyram+tebuconazole and Ampelomyces quisqualis M-10 fungicides with active substance decreased the disease severity by 63,27% and 45,86%, respectively. As a result of the study, it has been concluded that as a plant activator of A-S-M is effective as fungicide application in preventing disease development. Combination of fungicide and plant activators in future research is thought to be promising in control of powdery mildew disease on hazelnut.