ABSTRACT Alternaria leaf blight is an emerging and economically important fungal disease of apple trees in several apple‐growing regions worldwide including northern India. It is caused by different species of Alternaria with A. alternata being the dominant species in India. A. alternata usually causes light to dark brown necrotic lesions on apple leaves, but appearance of brownish lesions on the petiole and along the leaf margin were typically observed at different locations in dry‐temperate Himalayan regions in India during June–July for two consecutive years, that is, 2024 and 2025. The disease index ranged from 6.72% to 35.07%. Morphological studies revealed that conidia were brown to dark brown, obclavate or club‐shaped, multi‐septate measuring 6.8–30.4 μm × 2.9–14.28 μm in size and hence Alternaria tenuissima was reported to cause the leaf blight of apple in dry‐temperate Himalayan regions in India. The morphological characteristics of Alternaria species can change with the changes of environmental conditions and therefore, it is difficult to identify species of Alternaria based solely on morphology. Hence, molecular identification through Internal Transcribed Spacer (ITS) gene was carried out. Based on nucleotide homology and phylogenetic analysis, the pathogen was confirmed as Alternaria tenuissima , with NCBI accession no. PQ448223. To the best of our knowledge, this is the first report of Alternaria tenuissima causing leaf blight of apple in India.
Prashad et al. (Sun,) studied this question.
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