Etiology and Biological Control of Sclerotinia Blight of Coneflower Using Trichoderma Species

Kan-Fa Chang, Sheau-Fang Hwang, Heping Wang, George Turnbull and Ronald Howard

The present research was conducted to characterize possible biocontrol agents and to determine specific etiological factors affecting severity of infection by S. sclerotiorum. Greenhouse studies showed that incubation period, inoculation technique and temperature had significant effects on sclerotinia blight of coneflower. Longer periods of incubation after inoculation usually induced more infection in both Echinacea pallida and E. purpurea, although the former was more susceptible. For E. pallida, E. purpurea and E. angustifolia, seedling wilt and root rot symptoms caused by S. sclerotiorum were most severe when inoculum was placed 1 cm from seedling roots and diminished as the distance increased. Seedling wilt and root rot were more severe in plants grown at 5-15°C than in those grown at 10-25°C. A total of 74 strains of Trichoderma sp. were evaluated for antagonism against S. sclerotiorum in vitro. Strong or very strong antagonism was identified in 36 strains. This antagonism was confirmed for selected strains in greenhouse evaluations. Under field conditions, the efficacy of the Trichoderma treatment surpassed that of the fungicide fludioxonil and a Bacillus sp. biocontrol agent. These results suggest that certain Trichoderma strains have an excellent potential for use in managing sclerotinia blight of coneflower.

View Fulltext Back