Sources, survival and transmission of Cryptosporiopsis sp., leaf and nut blight pathogen of cashew (Anacardium occidentale Linn)

Abstract

The germination of conidia was studied from 2 hours to 16 hours after incubation at an interval of two hours period. The germination of macroconidia microscopically was followed to understand the timing of key events. Ten infected cashew nuts were placed each on a Petri dish containing malt extract agar and incubated at 27 °C for 10 days. Cryptosporiopsis sp. pathogen was detected in nut samples of cashew clones. Leaf and nut blight pathogen remained viable up to one year in plant debris stored under laboratory condition at a minimum temperature range from 4 to 5 °C. There was a rapid population decline on viable counts of Cryptosporiopsis sp. recovered from sterile and unsterile soil after various periods of time. In debris buried at a depth of 7 cm in sterile or unsterile soil they survived for four months with 8% and 5% of disease samples with viable pathogen. Saprophytic survival capacity of the fungus Cryptosporiopsis sp. in cashew field revealed that the pathogen survival was 80% up to four months of incubation but fell to 40% after 6 months. It was demonstrated that plant debris, soil and nuts could harbour sufficient inoculum to cause disease in new plants.