常春藤疫病

Abstract

A total of 25 isolates (9 Al : 16 A2) of Phytophthora palmivora were isolated from diseased tissues of English ivy in 7 fields in Taiwan, recently. P. palmivora attacked the whole ornamental plants including leaves, stems, and roots. Infected leaves became bleached, water soaking and dropped. Infected stem tissues turned bleached and browning. The affected plants dropped and wilted, and eventually died if basal stems or main roots were infected. Disease generally occurred under moist conditions and was especially serious during rainy seasons. On the inoculated plants, all test isolates of P. palmivora caused symptoms similar to those occur under natural field conditions in pathogenicity tests. P. palmivora was reisolated from the diseased tissues of inoculated plants. Isolates of P. palmivora from ivy grew on V-8 agar medium ranging from 12 to 35 ℃ and the optimum growth temperatures were 27-30 ℃ . All Taiwanese ivy isolates of P. palmivora belong to the typical types. Phytophthora disease of English ivy was reported the first time in Taiwan.