Leaf, panicle, and fruit blight of litchi ( Litchi chinensis) caused by Alternaria alternata in Bihar state, India

Abstract

India is one of the leading litchi (Litchi chinensis Sonn.) producing countries in the world. A leaf blight on litchi was observed in April 2012 on nursery plants at Muzaffarpur, Bihar, India. Light to dark brown necrosis starting from leaf tips resulted in complete drying of leaves. Blighting of panicles and fruits were also noticed during April–June, 2014. Panicles dried out as a result of necrosis, while necrosis of pedicels led to complete drying of the rind of developing fruits. Infected tissues collected from different sites in diseased fields were cultured on potato dextrose agar (PDA), and the pathogen was identified as Alternaria alternata (Fr.) Keissler on the basis of morphological and cultural characteristics. The fungus produced greyish-black colonies on PDA with obclavate or obpyriform conidia in chains. Conidia had 1–4 transverse and 0–3 longitudinal septa, and measured 16–40 × 4–13 μm. Morphological identification was confirmed by sequencing the internal transcribed spacer (ITS) region of rDNA using ITS1 and ITS4 primers. Pathogenicity tests indicated that A. alternata infected and caused blights of the leaves, panicles and fruit of litchi. Alternaria alternata has been reported to cause post-harvest decay of litchi fruit, but this is the first report of A. alternata causing blights of leaves, panicles and fruit in the field.