PRESENCE AND INOCULUM DENSITY OF Phytophthora IN DIFFERENT COCONUT CULTIVARS IN DAVAO RESEARCH CENTER (DRC)
Abstract
Presence of Phytophthora palmivora was both obtained in the soil samples and organic debris layed in leaf axil of coconut. Block planted to CAMT x MRD hybrid had the highest number of Phytophthora propagules (2.0). This was followed by CAMT (1.4) and KINGD (1.1). Aromatic and Catigan Green Dwarf had the least Phytopthora propagules collected.
Isolation of Phytophthora from the soil samples and organic debris from leaf axil was done thru dilution plate and baiting method respectively using six month old Malayan Red Dwarf (MRD) nuts. Highest infection (100%) on bait nuts was also obtained in CAMT x MRD hybrid 3.5 days after inoculation. Reisolation of Phytophthora from bait nuts gave positive results. Morphological characterization of the sporangium showed considerable variation in shapes and size.
More Phytophthora propagules was obtained in soil samples collected in areas previously planted with Malayan Yellow Dwarf x West African Tall (MAWA). Phytophthora palmivora is basically a soil borne pathogen but could easily be transported by wind and rainsplash, tent building ants and flying beetles,.
References
__________, E.C. CONDIBIDO-MANOHAR and E.S. POLIQUIT 1999. Studies on the Effect of Farm Sanitation and Fungicide Treatment on the Incidence of Phytophthora Disease of Coconut. Philipp. J. Coconut Studies 24(2): 6-11.
BARNETT, H.L. and B.B. HUNTER 1972. Illustated Genera of Imperfect Fungi. 3rd ed. Burgess Publishing Company. Minnesota 180 p.
BENNET, C.P.A., D. ROBOT, D. SITEPU and A. LOLONG. 1986. Pathogenicity of Phytophthora palmivora (Butl.) Butl. Causing premature nutfall disease of coconut (Cocos nucifera L.) Indoonesian Journal of Coconut Science 2(2) : 59-70.
BRASIER, C.M. and M.J. GRIFFIN 1979. Taxonomy of Phytophthora palmivora on cacao. Trans. Of the British Mycrofical Society (72) : 11-143.
CONCIBIDO, E.C. 1990. Distribution and comparative studies of Phytophthora disease of coconut (Cocos nucifera L.) in the Philippines.. Unpublished M.S. Thesis, UPLB 74 p.
GUEST, D. 2002. Understanding disease cycles of Phytophthora in the tropics. Proceeding on the Workshop on Phytophthora in Southeast Asia. Chaing Mai, Thailand. 8-12 Nov. 2002
POLIQUIT, E.S. and R.G. ABAD, 1999. Studies on the pathogenicity and host range of coconut, durian and cacao Phytophthora isolates under controlled conditions. Philip. J. Coco. Studies 24(2) 1-5.
QUILLEC, G. and J.L. RENARD 1984. Phytophthora rot of coconut, Oleagineux 39(3):143-145.
REINKING, O.A. 1923. Comparative study of Phytophthora faberi on coconut and cacao in the Philippine Island. J. Agric. Res. 25:167-264.
RILLO, E.P. and M.B.F. PALOMA. 1989. Reaction of some coconut cultivars and hybrids to Phytophthora disease. Philipp. J. of Coconut Studies 14(1) : 2-6.
WATERHOUSE, G.M. 1974. Phytophthora palmivora and some related species. In Phytophthora Diseases Cocoa (ed. P.H. Gregory), pp 51-70. Longman. New York.
