Disease status of Alternaria leaf blotch of apple in high density apple orchards of Kashmir valley

Abstract

By increasing productivity and land-use efficiency, high-density apple orchards (HDPs) are transforming temperate horticulture in Jammu & Kashmir. However, the microclimate inside canopies has changed due to the move to denser planting schemes, which may make trees more susceptible to foliar fungal diseases like Alternaria leaf blotch, which is brought on by Alternaria mali. Over the course of two consecutive seasons (2023 and 2024), the current study was conducted to evaluate the illness incidence and severity of A. mali across HDP blocks in three significant apple-growing districts: Baramulla, Pulwama, and Shopian. In order to measure the incidence and severity of disease on tagged leaves throughout orchards, a multi-stage survey methodology was utilized, with five sites per district and consistent procedures. The mean illness incidence and intensity in 2023 varied from 27.32% (Pulwama) to 30.11% (Baramulla), and 48.98% (Shopian) to 52.02% (Baramulla), respectively. All districts had a minor decline in mean incidence in 2024 (e.g., 25.08% in Pulwama and 26.69% in Baramulla), but intensity stayed high (e.g., 52.95% in Baramulla and 51.69% in Pulwama). According to pooled means, Baramulla had the highest intensity (52.48%) and Shopian the highest incidence (26.84%). Across the 30 sites that were surveyed, the combined illness incidence and intensity were 27.15% and 50.96%, respectively. With notable intra-district and inter-district heterogeneity, confidence intervals verify a constant illness pressure across the two years.