R.P. Gupta, K.J. Srivastava, U.B. Pandey
Diseases and insect pests play an important role in the production of onion in India. In the past decade, both prevalence and distribution of various diseases and insect pests have increased with devastating effect. Yield losses vary from 10–15% annually, depending upon the season and the prevalence of diseases and insect pests. Several diseases and insect pests have been reported in India, but in a recent survey conducted by the Foundation, only stemphylium blight (Stemphylium vesicarium) and purple blotch (Alternaria porri) diseases and onion thrips (Thrips tabaci) were identified as of national importance. Though colletotrichum blight (Colletotrichum gloeosporioides) disease was also found to be economically important, it was localized in Maharashtra State.

The results of the recent surveys conducted during the rainy season (1990) and winter/summer (1990–91) indicated that purple blotch was found to be severe in both periods, with 5.0–96.5% incidence and 0.09–25.93% intensity. Colletotrichum blight was restricted to the rainy season only, and its incidence as well as intensity ranged from 5.45 to 29.45% and 1.9 to 11.4%, respectively. Stemphylium blight was more severe in the winter/summer than in the rainy season (incidence 1.3–100% and intensity 0.04–25.8%). Thrips infestation was observed in both seasons but was more severe in the winter/summer crop (incidence 2%–100% and no. of thrips/plant 0.2–30.3).

Gupta, R.P., Srivastava, K.J. and Pandey, U.B. (1994). DISEASES AND INSECT PESTS OF ONION IN INDIA. Acta Hortic. 358, 265-270
DOI: 10.17660/ActaHortic.1994.358.43

Acta Horticulturae