Über die Schädlichkeit einiger Borkenkäferarten auf der Aprikose ( Prunus armeniaca L.)

Summary The harmfulness of some bark beetles is studied in connection with the infectious „Apricot Death”. Eccoptogaster rugulosus prefers a low wood water content — not above 14% — and therefore avoids healthy apricot trees which usually have a water content of 30–50%. On the other hand, Xyleborinus saxeseni needs moister conditions and is therefore more injurious as its development is associated with sound trees. The humidity is also of importance for the so‐called ‘Ambrosia fungi’ which the beetles cultivate in their galleries and this is probably the reason why artificial rearing is not successful. The fungus Trichoderma lignorum usually also occurred in the galleries and caused the withering of infected twigs by inoculations with mycelium. Attack by X. saxeseni is not of a primary nature but follows weakening of the tree due largely to adverse climatic conditions.