LETTERS TO THE EDITOR |
Letter to the Editor: Cotton (Gossypium herbacium L.) is one of the main commercial crops cultivated in this region. In Kharif (Autumn) season 2009, plants cultivated in various fields, showed symptoms of the leaf blight. The diseases is initially observed as a small, irregular, purplish spot generally on the older (i.e. lower) leaves which spread slowly to upper leaves of the plants. The color of the leaf spot first changes to brown and finally become black. On increasing in size these spots develops concentric rings which have alternating tan and brown bands. The symptoms were similar to those caused Ascochyta pinoides on pea plants (Gupta and Paul, 2001). One interesting thing is that the genetically modified (Bt) variety of cotton was found to be susceptible to the pathogen in this region during rainy season with high humidity condition. The fungus was isolated on PDA medium from infected leaves in the month of August 2009 from Devalgoan Bazar a village 90 Km away from Aurangabad in the north. For pathogenicity test (Six plants of same susceptible variety of cotton, with and without injuries were sprayed separately with suspension cultures of the Ascochyta pinoides in in-vivo). Control was sprayed with sterile distilled water and all the plants were covered with plastic initially for about 48 h. After 25-30 2 days, typical symptoms resembling with the original were observed on those plants inoculated with Ascochyta pinoides and the control were free from infection and symptoms. The pathogen produced globose, irregular depressed, light to dark brown pycnidia. They measure 65-175 μm in diameter. Pycnidiospores straights to curve with prominent construction; 14× 4.5 μm. The fungus colony was flat, whitish to light gray in colour soon become oliveceous black pigmentation was formed. Based on the morphological and cultural characteristics, the pathogen was identified as Ascochyta pinoides (Berk and Block) Stone. This is the first report of Ascochyta blight on Gossypium herbacium L. in Maharashtra state of India and it seems to be first report of a species Ascochyta pinoides on Gossypium herbacium. REFERENCES |
Zafar S Khan1*,
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