Late Oak Mortality Caused by Gypsy Moth (Lymantria dispar L.) in the Bienwald District, Germany : Disease/Environment Interactions in Forest Decline. Proceedings of a Workshop of the Working Party Disease/Environment Interactions in Forest Decline IUFRO 7.02.06, Vienna, Austria, March 16-21, 1998

1999

S. 35-42

3 Abb., 20 Lit.

Unselbständiges Werk

200085317

In 1993 and 1994 the oak stands of the Bienwald were seriously defoliated by gypsy moth caterpillars, followed by mildew contamination. As a result many oaks died, whereas control measures employing the aerial application of insecticides were highly successful in reducing oak mortality. The primary mortality and decline in 1995 was apparently caused by a physiological drying up of oaks, mainly due to fine-root losses under anaerobic conditions and the reduced development of early wood. Due to the defoliation and the sudden damage in 1995, some secondary invaders profited from the resulting conditions. Since summer 1995, the oak borer (Agrilus biguttatus F.) became the main threatening factor. In addition to this, heartwood destroying insects infested declining oaks. Many other detrimental effects are continuing to appear.