POWDERY MILDEW OF CORIANDER CAUSED BY Erysiphe polygon D.C. AND IT'S MANAGEMENT
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Date
2002
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AAU, Anand
Abstract
Coriander (Coriandrum sativum L.) is an important spice crop. Coriander seeds and fresh coriander leaves are consumed as spice and for flavouring various culinary preparations, respectively. It is native of Mediterranean region. Today coriander is commercially grown in India, Morocco, Russia, Hungary, Poland, Czechoslovakia, Rumania, Guatemala, Mexico, USA, Bangladesh and Pakistan. Coriander belongs to family Apiaceae. In India, it was estimated that coriander is grown over an area of 3,22,000 hectares with a production of 3,08,000 hectares in the year 1997-98, while export of coriander seeds to foreign countries was to the tune of 26,826 metric tonne valued at around Rs. 58 crores for the year 1998-99. The crop can earn valuable foreign exchange. Powdery mildew is a major disease of coriander caused by Erysiphe polygoni D.C. The pathogen is air borne. It cause losses up to 15-40% in addition to considerable loss in quality of coriander seeds. Present investigations were carried out on patliogenicity, inlluence of sowing dates and weather parameters on development of disease, screening of germplasms/varieties, field evaluation of fungicides, phytoextracts and water spray against E. polygoni, at Vegetable Research Station, GAU, Anand. During the study in Rabi 2000-2001, it was observed that the powdery mildew of coriander appeared in late December - January - February and increased till harvesting. Infected plants showed typical symptoms of white ashy powdery coverage on foliar parts and stem. The fungus could not he multiplied under laboratory conditions. Therefore, in order to prove the pathogenicity, conidia obtained from the diseased plant parts were sprayed on plants of cultivar Gujarat Coriander-2. Among various sowing dates under study, the early sowing dates i.e. 20th October and 5th November were found superior to subsequent sowing dates i.e. 20th November, 5th December, 20th December and 5th January. Environmental factors played an important and vital role in development of disease. Periodical progression of disease intensity increased from 16.40 to 57.60 per cent. Positive and significant correlation was observed in case of wind speed and positive but non-significant correlation in case of maximum, minimum and mean temperatures. Disease was initiated in between late December to Early January. Among twenty-six different germplasms/varieties screened, no variety was found immune or resistant to powdery mildew infection. However, the germplasms CM-17, CM-26 and CM-25 recorded lower disease incidence i.e. 48.26, 50.93 and 51.20 per cent, respectively. Among different fungicides and phytoextracts tried in control of powdery mildew of coriander, Dinocap proved to be most effective fungicide followed by wettablc Sulphur with respect to disease intensity, seed yield and oil content. Phytoextracts were found next to fungicides in respect of disease control.
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Keywords
Plant Pathology, Agriculture, A Study