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Disease Note.

First Report of Fusarium oxysporum and Fusarium solani Associated with Root Disease of Caribbean Pine in Venezuela. S. R. Mohali, Electron Microscopy Center, University of Andes, Apdo. 163, Merida 5101-A, Venezuela. Plant Dis. 80:959. Accepted for publication 13 May 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0959C.

In 1993, a generalized wilting and chlorosis of the foliage was observed in 3-year-old trees in two seed orchards of Caribbean pine (Pinus caribaea P. M. Morelet var. hondurensis Barr. & Golf) in the state of Falcon, Venezuela, belonging to the company CVG-PROFORCA. Symptoms were present in 6.5 and 10% of the trees in seed orchards of 20 and 14 ha, respectively. Symptomatic trees were characterized by extensive mortality of small feeder roots and copious resin exudation on the larger roots. Isolations from symptomatic plants on 2% water agar and potato dextrose agar, both acidified with 3.3 ml of 50% lactic acid per liter, yielded primarily Fusarium oxysporum and F. solani. These species were isolated from 40 and 60%, respectively, of the tissue samples plated. Both species were occasionally isolated from roots of the same tree. Their pathogenicity was determined through inoculation of 3-month-old bare-root seedlings of Caribbean pine. The root systems were surface disinfected with 0.5% NaOCl for 5 min and rinsed three times in sterile distilled water. The seedlings were replanted in a sterile mixture of sand/vermiculite (1:1) and inoculated separately with spores and mycelial fragments. Seedlings inoculated with either fungus exhibited wilting of foliage in 5 days, chlorosis and root necrosis after 15 days, and mortality 1 month after inoculation. No differences in degree of infection were noted between the two Fusarium spp. Noninoculated seedlings remained healthy. This is the first report of these two Fusarium spp. on Caribbean pine in Venezuela.