Lychee Diseases and its Viable Control

Abstract

Litchi chinensis Sonn. is a common fruit of India especially grown in the state of Bihar and surrounding states. Common forest regions, botanical gardens, and plant conservatories were surveyed at a regular interval of 3 months during the period April 2002 to March 2012 for the collection of diseased samples under the AICOPTAX program. During the course of the survey a number of diseases such as tar leaf spot were observed. Older leaves show a higher percentage of infections than younger leaves. The diseased leaves serve as the source of primary infection. The leaf spots spread rapidly during humid and rainy months. The lesions coalesced at the later stages. The diseased leaves show yellow brown to brick red areas, mostly towards the margins. The percentage of disease incidence varied in different localities. The coloured areas gradually become light brown and show black pinheads resembling pycnidia. Pestalotia pauciseta Sacc., Botryodiplodia theobromae Pat., and Colletotrichum gloeosporoides occur very commonly in litchi orchards, causing tar disease. Another serious leaf spot disease is incited by Microdiplodia litchi and Clitocybe tabescence. Sudden wilt caused by Fusarium sp., dieback from Phomopsis, and foliar necrosis caused by Gloeosporium spp. are reported. Some of the post-harvest diseases are carried along with the fruits during transit and storage. Among these pathogens, such as Botryodiplodia theobromae, Colletotrichum gloeosporioides, Cylindrocorpon forkinense, Phomopsis spp. and species of Pestalotia are the most important and need attention as they also cause diseases on the plants. Spraying of leaf extracts of Andrographis paniculata, Azadirachta indica, Plumbago zeylanica, and Ocimum sactum reduced the infection; however, fungicides such as bavistin, topsin M, baycor, and dithiocarbmates were found to be very effective to control the disease.