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Infection of Pepper and Tomato by Phytophthora capsici. G. L. Hartman, Asian Vegetable Research and Development Center, Shanhua, Tainan, Taiwan 74199, Republic of China. Y. H. Huang, and T. C. Wang. Asian Vegetable Research and Development Center, Shanhua, Tainan, Taiwan 74199, Republic of China. Plant Dis. 75:751. Accepted for publication 5 March 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0751C.

Phytophthora blight, caused by Phytophthora capsici Leonian, of pepper (Capsicum annuum L) and late blight, caused by P. infestans (Mont.) de Bary, of tomato (Lycopersicon esculentum Miller) occur annually in Taiwan. Ho (1) recently questioned the extent of late blight occurrence and in his review of Phytophthora spp. occurring in Taiwan found no evidence of the fungus on tomato or any confirmed reports of late blight since 1919. We isolated P. capsici from blighted tomato leaves in the Hsinyi highland of central Taiwan. Our objective was to determine the pathogenecity of P. capsici isolated from tomato and pepper. Thirty-day-old tomato (14 lines) and pepper (cv. Blue Star) plants were inoculated with 103 and 105zoospores per milliliter by either atomizing foliage or drenching soil; isolate Pc 9 from blighted tomato leaves and isolate Pc 1- 5 from blighted pepper stems were used. Plants were incubated in a growth room under 100% relative humidity at 28 C. Upper leaves, petioles, and atema of pepper and tomato plants were blighted 7 days after inoculation wilh Pc 2. Pc 4, Pc 5, and Pc 9, whereas Pc I and Pc 3 caused only slight necrosis of newly formed leaflets at 105 zoospores per milliliter. All isolates caused typical Phytophthora blight symptoms on pepper stems, but no isolale caused symptoms on tomato when soil was drenched with inoculum. Both P. capsici and P. parasitica Dast. are known to cause root and crown rot of tomato (2). Our data indicate, however, that some P. capsici isolates cause foliar blight of pepper and tomato but not crown rot of tomato. This apparently is the first report of P. capsici causing blight of tomato foliage.

References: (1) H. H. Ho. Bot. Bull. Acad. Sin. 31:89, 1990. (2) M. M. Satour and E. E. Butler. Phytopathology, 57:51O. 1961.