Green Treefrogs as Vectors of Colletotrichum gloeosporioides. X. B. Yang, Department of Plant Pathology, 217 Plant Science Building, University of Arkansas, Fayetteville 72701. D. O. TeBeest, Department of Plant Pathology, 217 Plant Science Building, University of Arkansas, Fayetteville 72701. Plant Dis. 76:1266-1269. Accepted for publication 28 July 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-1266.

Green treefrogs (Hyla cinerea), commonly observed in southern Arkansas rice fields, were efficient dispersal vectors for Colletotrichum gloeosporioides f. sp. aeschynomene, a causal agent of anthracnose of northern jointvetch. In four experiments, frogs captured from rice fields infested with diseased northern jointvetch were placed in containers with healthy northern jointvetch plants. An average of 90% of the northern jointvetch plants became infected by the pathogen with up to 10 lesions per plant. Dispersal by frogs was further quantified in greenhouse experiments by monitoring disease development from a point source in simulated rice-weed patches. The frogs moved the pathogen from a source plant to healthy plants, resulting in 95% infection. Densities of treefrogs in 16 surveyed weed patches of eight rice fields varied from 0.3 to three per northern jointvetch plant. Shelter selection experiments showed that in patches consisting of 336 rice tillers and 10 northern jointvetch plants, green treefrogs preferred northern jointvetch to rice at a ratio of 133:1, presumably because northern jointvetch is taller than rice. The fact that green treefrogs prefer northern jointvetch may contribute to the efficacy of the treefrogs as vectors of C. g. aeschynomene.

Keyword(s): biocontrol, epidemic.