Author: Parmar Harshil Vinodbhai
Cotton is one of the most important commercial crop and it is the back bone of national economy of country. No other fiber comes close to duplicating all of the desirable characteristics combined in cotton. It provides thousands of useful products and supports millions of jobs as it moves from' field to fabric (www.cotton.org ). Cotton is a white fibrous agricultural product that has a wide variety of uses, from textile production, to creating paper, to producing oil and food products. Cotton is grown all around the globe and is traded internationally as well.
The production is influenced by the repeated out breaks of pest and diseases and these are the major factors responsible for lower yield of cotton in India, In India, 30 diseases have been reported for cotton crop. Out of these 17 are caused by pathogens of fungal origin, four of bacterial nature, two are of nematodes and many known and unknown viruses and physiological disorders (Seklion et al., 2008).
Major Cotton Diseases in India
- Wilt (Fusarium oxysporum f. sp. Vasinfectum (Atk.) Snyder & Hansen)
- Root rot (Rhizoctonia solani Kuhn, R. bataticola (Taub) Butler), Scattered
- Bacterial leaf blight (Xanthomonas campestris pv malvacearum (Smith) Dye), Maharashtra, Gujarat, Karnataka
- Cotton leaf curl (Gemini virus), North zone (Potential threat)
- Alternaria leaf spot (Alternaria macrospora Zimm.), Maharashtra, Gujarat, Karnataka
- Grey mildew (Ramularia areola Atk.), Central & South zone (Emerging)
- Myrothecium leaf spot (Myrotheciumroridum Tode ex Fr.), Madhya Pradesh
- Leaf Rust (Phakopsora gossypii (Arth) Hirat F.), Karnataka, Andhra Pradesh (Emerging)
- Cercospora leaf spots (Cercospora gossypina Southw.), Andhra Pradesh (Minor) • Helminthosporium leaf spot (Helminthosporium spiciferum (Bain) Nicot), Andhra Pradesh
- Anthracnose (Colletototricum gossypsii South w) South zone (Minor)
- Leaf reddening
- Verticillium wilt (Verticillium dahlia Khleb.), Tamil Nadu, Karnataka The diseases of economic significance that affectcotton are few viz., bacterial leaf blight, alternaria leaf spot, grey mildew, root rot and boll rot etc. However, in certain areas or in some seasons they can cause heavy losses in both yield and quality. The bacterial leaf blight is the most wide spread and destructive disease reported to cause yield losses of about 10 to 30 per cent (Kalpana et al., 2004) and also affect the quality of lint (Sharma and Chauhan, 1985). Bacterial leaf blight, boll rots, wilts and leaf spots are the most destructive cotton diseases (Chopra, 1977). Under natural, bacterial blight infection, boll yield losses up to 35 % have been reported (Sheo Raj and Verma, 1988). Leaf spots rank third among the diseases on cotton in India. Among the leaf spots, bacterial blight (Xanthomonas campestris pv.malvacearum (Smith); Alternaria leaf spot(Alternaria macrospora Zimn) and grey mildew (Ramularia aereola) have been reported to be damaging. Bacterial leaf blight (BLB) of cotton caused by Xanthomonas campestris pv. malvacearum (Smith) Dye affects the entire aerial parts of cotton plant i.e. necrosis of parenchymatous tissue in the local phase and blockage of xylem vessels in its systemic phase (Casson et al., 1977).
Chopra, B. L. 1977. Important diseases of cotton and their control measures in India. Paper presented at staff course on cotton production its processing and marketing technology held at P.A.U., Ludhiana.
Kalpana, P., Chellamuthu, V. and Jeyalakshmi, C. 2004. Screening of cotton hybrids against bacterial blight incited byXanthomonas campestris pv. malvacearum (Smith) Dye, Paper presented in Inter. Symp. Strat. Sust. Cotton Prod. - A Global Vision 3, Crop Production, 23-25 Novermber 2004, Univ. Agric. Sci., Dharwad (India), pp. 373-374.
Sheo Raj and Verma, J. P. 1988. Diseases of cotton in India and their management. Review of Tropical Plant Pathology, 5: 207-254.
Sekhon, P. S., Singh, D. and Singh, G. 2008. Cotton pathology research achievements and targets in Punjab. All India Coordinated Cotton Improvement Project Report. PAU, Ludhiana.
Sharma, B. K and Chauhan, M. S. 1985. Studies on the chemical control of foliar diseases of cotton in Haryana state. Agric. Sci. Digest. 5:153-56.
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