Impact of Meteorological Parameters on the Development of Alternaria Leaf Spot of Brinjal (Solanum melongena L.) Caused by Alternaria alternata (Fr.) Keissler under Natural Epiphytotic Conditions

Abstract

Brinjal (Solanum melongena L.), commonly known as eggplant or aubergine, is a widely cultivated vegetable crop in India and across the world, but its productivity is often limited by fungal and bacterial diseases, among which Alternaria leaf spot caused by Alternaria alternata is a major concern. The present study was conducted during Rabi seasons 2021–22 and 2022–23 at the Experimental Field, College of Agriculture, Gwalior, to assess the influence of meteorological parameters on the development of Alternaria leaf spot disease of brinjal (Solanum melongena L.). The experiment consisted of five different sowing dates. Observations on disease intensity and corresponding weather parameters namely temperature, relative humidity and rainfall were recorded weekly. The susceptible variety BR-112 was used for the study. Results revealed that Alternaria leaf spot first appeared in early January and gradually increased until the first week of March. Correlation analysis revealed a positive and significant association between disease intensity and both maximum (r = 0.6266**) and minimum temperatures (r = 0.7986**). In contrast, morning (r = –0.5101**) and noon relative humidity (r = –0.5187**) exhibited significant negative correlations with disease intensity. Rainfall showed a negative but non-significant correlation (r = –0.2285). These results indicate that higher temperatures favor the development of Alternaria leaf spot in brinjal, whereas increased relative humidity and rainfall tend to suppress disease progression.