Reaction of oriental Hevea clones to isolates of Microcyclus ulei and the response of isolates to fungicides

Abstract

Hevea clones from Sri Lanka, Malasia and India were assessed in vitro for their resistance to four isolates of microcyclus ulei. Clones SL 26, R-14, 5B/17/4, and 1/2/56/77 were infected by all isolates of M. ulei tested. However, they were found to have some resistance to M. ulei. Propiconazole was more effective than Triforine and Triadimefon in inhibiting germination of conidia of M.ulei. These fungicides were also effective in inhibiting lesion formation. Triadimefon (Bayleton 50 w.p.) had a better curative effect than propiconazole (Tilt 25 EC) and Triforine (Saprol). The effect of Triadimefon on germination of conidia varied between isolate while the effect varied little between isolates for propiconazole and triforine. The effect of the fungicides on the number of lessios on leaf discs did not show major differences between iaolates.