SEVERITY, ETIOLOGY, AND DISTRIBUTION OF EARLY BLIGHT DISEASE ON POTATO IN GILGIT-BALTISTAN REGION, PAKISTAN

Abstract

Potato, one of the world's most important crops, is susceptible to various pathogens, including Alternaria alternata and Alternaria solani, responsible for early blight disease (EB). This study aimed to assess the prevalence and incidence of EB in nine valleys (Gouro, Nalter, Nomal, Jutal, Chilmish, Bagrote, Danyore, Jalalabad, and Oshikhandas) of Gilgit Baltistan (GB), Pakistan, and identify the dominant Alternaria spp. causing the disease. A comprehensive field survey was conducted in these valleys, encompassing 45 fields. The survey revealed variations in the prevalence, incidence, and severity of early blight across different locations. Nalter exhibited the highest prevalence at 58%, with an incidence of 29% and disease severity of 9.67%, indicating a substantial impact on potato crops. Bagrot and Gouro also reported substantial prevalence rates of 53% and 49.33%, respectively, with notable incidence and severity. In contrast, the Oshikhandas and Danyore regions had the lowest disease severity, signifying less extensive damage. To understand the pathogens responsible for early blight, 60 isolates were collected and identified. A. alternata was the dominant species, with 60 isolates, while A. solani was identified in only 5 isolates. A. alternata exhibited characteristic dense and multi-colored growth, particularly when cultured on PDA media. Microscopic examination confirmed its identity, with short chains of conidia showing a distinctive beak-like projection. Notably, the GIS maps show that the northwestern section exhibits higher disease incidence than the northeastern part, emphasizing the non-uniform distribution of EB. In conclusion, this research is important to understand the disease's dynamics and can inform targeted management strategies to mitigate its impact on potato crops, contributing to enhanced food security and agricultural sustainability.