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Phytophthora Crown and Root Rot of Mango Detected in Philippine Nurseries. P. H. Tsao, University of California, Riverside 92521. P. B. Luzaran, A. B. de los Santos, L. A. Portales, A. M. Gochangco, and L. C. Gruber, Philippine-German Biological Plant Protection Project, Bureau of Plant Industry, Manila, Philippines 1004. Plant Dis. 78:100. Accepted for publication 27 September 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/PD-78-0100C.

Phytophthora palmivora (E.J. Butler) E.J. Butler was isolated from infected crown and root tissues of mango (Mangifera indica L.) showing crown and/or root rot and wilt symptoms in the Philippines. Selective media of P10VP and PARP were used for isolation. Isolate RP-17 (mating type A) was recovered from a 2-yr-old budded tree (cv. Carabao on Indian rootstock) in February 1989 in Santa Barbara Provincial Nursery in Tebag, Pangasinan, and isolates PG-63 (mating type A2) and PG-64 (mating type A) were recovered from two 2-mo-old Carabao seedlings in November 1990 in Davao Experiment Station Nursery in Bago Oshiro, Davao. Pathogenicity tests were performed on 8-mo-old Carabao seedlings by inoculating the lower stems with 3-mm disks of mycelium agar of RP-17 and PG-63.Gumming on barks begun 2 3 days after inoculation. The bulks were stripped, and lesion areas were traced and measured 14 days later. RP-17 and PG-63 produced lesions of 201 and 176 mm2, respectively, compared with 3-mm2 lesions in control seedlings that received agar disks without Phytophthora. P. palmivora was reisolated from the bark lesions, and the reisolates were morphologically identical to the two original isolates. This is the first report of Phytophthora crown and root rot of mango in the Philippines since a brief report of an undiagnosed seedling blight in 1921 (1).

Reference: (I)O. A. Reinking. Philipp. Agric. 9:121, 1921.