Etiology of sooty blotch disease of Aegle marmelos and its management

Abstract

Aegle marmelos (L) Correa. recognized as bael is widely grown in the Eastern and Northern states of India. Incidence of superficial smudgy fungal blotch symptoms were observed on bael fruits in our experimental farm located in the state of Odisha, Eastern India (20°14’ N, 85°46’ E). The fungal blotch colonies on the fruit skin reduced the visual appeal of the fruits and thereby drastically reduced the market value and saleability of fruits. Etiology of fungi growing on the waxy layer of fruits resulting sooty blotch symptoms were investigated. Among different mycelial types observed on fruits, ramose colony type was observed as predominant (up to 80 %) followed by fuliginous and punctate type of colonies. Representative colonies were subjected to isolation; cultures were purified and analysed based on morphology and sequences generated with nuclear ribosomal genetic marker, the Internal Transcribed Spacer (ITS) nr DNA region and proved for Koch’s postulates. The three fungal isolates were identified based on ITS phylogeny viz., Zasmidium sp. (ISO141), Passalora sp. (ISO211) and Pseudocercospora sp. (ISO232) however assigned putative status as the cultures were sterile. Among the various pre-harvest management modules evaluated in an effort to produce blemish-free bael fruit, the field spray of 0.3 percent copper oxy chloride (first spray at the lemon stage, second and third spray at 15 and 30 days after the first spray, and the last spray at 30 days before harvest) resulted 95-97 percent blotch control in two varieties of bael CISH-B1 and NB-5 taken for study.