Effect of environmental factors on diseases of betelvine (Piper betle) in Assam

Abstract

The cultivation of betelvine is hindered by a number of fungal and bacterial diseases resulting in heavy loss in leaf yield every year. Environmental factors play an important role on growth, dissemination and infection of pathogen as well as influence the expression of susceptibility/resistance of the host plant after infection. Therefore, an experiment was undertaken to study the influence of temperature, humidity and rainfall on the development of the diseases of betelvine under Jorhat conditions. The intensity of major diseases of betelvine viz anthracnose leaf spot caused by Colletotrichum capsici (Syd.) Butler and Bisby, and bacterial leaf spot caused by Xanthomonas axonopodis pv. betlicola (Vauterin et al. in Int J Syst Bacteriol 45:472–489, 1995) aggravated during rainy season. Percent Disease Index (PDI) of anthracnose leaf spot increased from 0% in November–March to 30.1% in July. PDI of bacterial leaf spot (30.6%) reached its peak during the months of August–September. Anthracnose did not appear during the months from November to April. However, PDI of bacterial leaf spot gradually decreased from September to 0% in March. Relationship between disease severity of anthracnose leaf spot and the meteorological parameters (maximum and minimum temperature, evening relative humidity and rainfall) was strong and positive. A moderate positive linear relationship was observed between disease severity of bacterial leaf spot and the meteorological parameters such as maximum temperature and evening relative humidity. However, strong positive linear relationship was observed with minimum temperature and rainfall.