Diseases and pests threatening forest ecosystems in Bosnia-Herzegovina

Abstract

Mistletoe Viscum album is wide spread on silver-fir (Abies alba) causing over 100% reduction of average volume increment of the infected trees within 42,5 cm diameter class. Silver fir trees of all ages are attacked due to over-cutting in past. In succession attack of some bark beetles (Pityocteines curvidens and other) or Armillaria root rot fungus occur and they are responsible for final dying of the infect­ed trees. It is considered that only proper management with the silver-fir forests may prevent the occurrence of the mistletoe.

Severe current outbreaks of the bark beetles (Ips typographus and Pityogenes chalcographus) on spruce (Picea abies) are studied. These insects really threat to the existence of spruce stands and some are already clear cut. Experiments on the popula­tion dynamics and effect of the pheromones in the bark beetle trappings, in the area of the city of Sarajevo, show that these insects have two generations. First one has its maximum at the beginning of June and second one during the first decade of August. Density of the population of the first generation was over 3500 insects per trap what is considered over the critical threshold.