Characterization of Phytophthora palmivora isolates inciting bud rot and nut rot in coconut
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Date
2010
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Abstract
Cultural and morphological characters of 35 isolates of the Phytophthora palmivora collected from rotting bud and nut of coconut were characterized. Basically the colonies were stellate or striate type. Rate of growth in carrot agar varied significantly among the isolates. Rate of growth was fast in Pp22 and Pp23 and slow in isolate Pp14. The sporangia of all the 35 isolates were found to be caducous and were shed with short, broad and occluded pedicel. All isolates of Phytophthora collected in the present study were found to be heterothallic and were of A2 mating type which produced oospores when paired with A1 isolates. Oospore formation in all isolates was noticed only after 15 days of pairing with an A1 isolate. From the above characteristics, all the 35 isolates were confirmed as Phytophthora palmivora Butl. Maximum growth of both bud rot and nut fall isolates of P. palmivora were observed at pH 6.5 (Mean dry weight, 62.36 mg). A temperature range of 25 and 270C supported maximum growth in both nut and bud rot isolates. Among organic Nitrogen sources, glutamine showed maximum dry weight of mycelium both in case of nut fall (58.27 mg) and bud rot isolates (57.00 mg) followed by those supplemented with L-asparagine.
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Bud rot, coconut, Kerala, nut fall, Phytophthora palmivora
Citation
Journal of Plantation Crops, 2010, 38 (3): 188-1932