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PHYTOPHTHORA SYRINGAE CAUSING CROWN AND ROOT ROT DISEASE OF APPLE IN MALAKAND DIVISION, PAKISTAN

JAHANGIR

Abstract: Phytophthora crown and root rot disease of apple is widespread in most apple growing areas of Malakand Division, Pakistan where Phytophthora cactorum and Phytophthora spp., have been reported from infected plants of apple orchards and nurseries (Jahangir et al., 1995 a,b). During a survey of apple nurseries in Malakand Division in 1996, nursery plants showing symptoms of small, pale-green leaves, sparse foliage and poor terminal growth in summer and reddish leaves in autumn seasons were collected. Soil samples from the hemispheres of the same plants and dead plants were also collected. Small pieces of crown and roots after washing in running tap water and surface sterilization with 1 % Sodium hypochlorite solution were transferred on VYSPCNB agar medium. Extended baiting method using apple seed cotyledons was used for the isolation of Phytophthora sp., from the soil (Jeffers & Aldwinckle, 1987). Phytophthora syringae was identified on the basis of colony, hyphal morphology and characteristics of sporangia after references to Ribeiro (1978) and Stamp et al., (1990). Pathogenicity of P. syringae was also tested by the method of Borecki & Millikan (1969). This is the first report of P. syringae causing crown and root rot disease of apple in Malakand Division, Pakistan on exotic root stocks of Malling-Merton-l06 and MM -111 recently introduced in the area.

Agricultural Research Station (North), Mingora, Swat, Pakistan.