Phytophthora Crown and Root Rot on Langsat Seedlings in the Philippines. P. H. Tsao, University of California, Riverside 92521. L. C. Gruber, L. A. Portales, P. B. Luzaran, A B. de los Santos, and A. M. Gochangco, Philippine-German Biol. Plant Protection Proj., Bureau of Plant Industry, Manila, Philippines 1004. Plant Dis. 79:424. Accepted for publication I November 1994. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0424E.
The tropical fruit tree Lansium domesticum Correa (langsat or lanzone) is widely cultivated in southeast Asia. Crown and root rot was observed on seedlings in some Philippine nurseries, from which Phytophthora palmivora (E. J. Butler) E. J. Butler was isolated by the use of P10VP and PARP selective media. Isolate RP-19 was recovered from roots of a 10-mo-old seedling in Manila, and isolate PG-68 was recovered from crown lesions of a 2-yr-old seedling in Davao. Both isolates were of the A1 mating type. Pathogenicity tests were performed on 15-mo-old langsat seedlings by inoculating the lower stems with 3-mm mycelium-agar disks of each of the two isolates. Control plants received agar disks without Phytophthora. After 14 days, the control-, RP-19-, and PG-68-inoculated plants produced bark lesions of 8, 126, and 119 mm2, respectively. The reisolates from the bark lesions were morphologically identical to the two original isolates. This is the only report of Phytophthora crown and root rot on langsat other than a briefly mentioned association of P. palmivora with langsat (but without indications of plant part in-fecled or country in which it occurred) by Chee (I)Reference: (I) K. H. Chee. Rev. Appl. Mycol. 48: 337, 1969.