ISHS Acta Horticulturae 494: II International Symposium on Chestnut
RESULTS ON BIOLOGICAL CONTROL OF CASTANEA SATIVA IN SLOVAKIA |
| Authors: | G. Juhásová, K.A. Kulcsárová, H. Ivanová, C. Robin |
| Keywords: | Castanea sativa, Cryphonectria parasitica, hypovirulence |
| Abstract:
The fungus Cryphonectria parasitica was reported in Slovakia for the first time in 1976. Up to the year 1998 it has spread onto 20 sites and within them onto 77 stands. We isolated only virulent isolates of this fungus from chestnuts and oaks until 1997. At the Moody Kamen and Duchonka sites, healing cankers were found on trees, which had not been treated by hypovirulent strains of C. parasitica in previous years. The virulent isolates obtained before 1997 were classified in 2 v-c types. In 1997 and 1998 virulent isolates from Slovakia were tested with European testers. Eight v-c types were identified in Slovakia. We suppose that the number of v-c types increased with the number of sites investigated. Since 1991 the cankers have been treated by 4 converted hypovirulent strains provided by INRA (Clermont-Ferrand, France). The aim of our work was to prove the efficiency of hypovirulent strains to treat cankers on chestnut. We found out that 4 hypovirulent strains were efficient to convert Slovak virulent isolates. In field conditions the treatment efficiency ranged from 20,3 % to 86,3 %. The number of isolates that were tested for vegetative compatibility ranged from 1 to 15 isolates per site (depending on the number of trees and cankers). The low efficiency of biological control may be caused by the high diversity of C. parasitica. In 1997 and 1998 the number of isolates that were tested for vegetative compatibility increased. If the conversion of virulent isolates by compatible strains is improved, the efficiency of biological control in field conditions will increase. | |
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