Pre-harvest occurrence and physico-chemical characterization of Cladosporium cladosporioides on grape in India

Abstract

Aim: The present study aimed to characterize Cladosporium cladosporioides C1 with respect to its pathogenicity, effect of different environmental factors and extracellular enzyme production. Methodology: A survey was conducted on C. cladosporioides in vineyards in Pune, Nashik and Sangli district of Maharashtra. The growth rate of C. cladosporioides was determined at different levels of temperature, pH and water activity. The pathogenicity of C. cladosporioides on both coloured and white table grape varieties with different total soluble solid (TSS) values was investigated along with its ability to produce different lytic enzymes required for pathogenicity. Results: The survey of the vineyards indicated that every vineyard was infected with C. cladosporioides irrespective of the infection level. The optimum growth of C. cladosporioides was noted at 25°C with pH 5 and 0.99 water activity (aw). Injured berries with high TSS were necessary to cause berry rot. Berries having 25% TSS developed significantly larger rot patches of 4.94±0.07 mm in white grapes as compared to berries having 15 % TSS. In the colored variety the berries having 25% TSS developed rot of 4.54±0.12 mm which was significantly higher as compared to berries having 15 % TSS. The fungi showed production of protease, lipase, amylase and pectinase enzymes. Quantitative analysis revealed that the yield of amylase was 71.67 %, which was significantly higher as compared to other enzymes. Interpretation: The information obtained on the growth of C. cladosporioides from the physico-chemical analysis would help to predict the development of the pathogen in the natural environment as well as formulate a strategy to control its pre-harvest infection. Key words: C. cladosporioides, Enzymes, Grapes, Pathogenicity