Zur Bekämpfung des Lärchenblasenfusses Taeniothrips laricivorus Kratochvíl und Farský (Thripidae, Thysanoptera) mit einem systemischen Insektizid

Birmensdorf

1956

S. 3-22

15 Abb., 8 Tab., 16 Lit. Ang.

Bandaufführung

157677

In summer 1955 Metasystox, a recently developed sytemic insecticide, was used in a control experiment against the larch thrips, Taeniothrips laricivorus Kratichvíl and Farský. The experiment was carried out in a larch plot of the Swiss Forest Research Institute. Bands of absorbent cotoon were wrapped around the trunks and both 2,5 and 5 per cent emulsive formulations were poured on them; the bands were then covered with polyaethylene strips, similarly to the method used by Jeppson, Jesser and Complin (1952). The effectiveness of the insecticide was evaluated statistically by ascertaining the following: a) the scabbing of the bark produced by the insect on the year's top branches, b) the condition of the terminal bud of the tree, and c) the height growth of the tree. The results of the treatment are very satisfactory. The 5 per cent emulsionis more effective than the 2,5 per cent one. The effectivness of a given dose of insecticide applied to trunks varying in size decreases with the increase of diameter, according to a determined regression line. The variety of larch trees has no bearing on the effectiveness of the treatment, although untreated larch trees of various provenances react differantly under attack of the thrips. This type of insecticde and the method used can be recommended for controlling larch thrips. However, further research would be needed on the metho of applying the absorbent bands and the plastic strips around the trunks, and also on the number of treatments necessary to protect alarch stand from attack of T. laricivorus in a durable way.