Biological control of powdery mildew and black spot diseases of rose

Abstract

Black spot, incited by the fungus Diplocarpon rosae wolf, and powdery mildew caused by Sphaerotheca pannosa var. rosae is a major problem in growing successful healthy rose gardens. Culture filtrates of Trichoderma harzianum, T. viridi and Pseudomonas fluorescence were evaluated to control powdery mildew and black spot disease of rose plants. Culture filtrates of the aforementioned biocontrol agents were used as 25, 50 and 75 per cent. Bioassays were conducted under field conditions during the two successive seasons of 2011 and 2012 at the experimental farm of the Faculty of Agriculture (FMAP) SKUAST-Kashmir to test the efficacy of these culture filtrates applied to protect rose plants from powdery mildew and black spot diseases. In vivo evaluation of bioagents revealed that Pseudomonas fluorescence was significantly superior followed by Trichoderma viridi (both at 75% concentration) whereas, T. virens was found to be least effective. The studies of two consecutive cropping seasons from 2010-2011 to 2011-12 showed the superiority of Pseudomonas flourescence in managing the disease effectively followed by Trichoderma Viridi. The biocontrol sprays also improve the quality of cut flowers.