Untersuchungen zur Anpassung der Bekaempfungsschwelle der Getreideblattlaeuse (Hom., Aphididae) (Saugschaeden an Weizen im Sommer) an die veraenderten oekonomischen Rahmenbedingungen im Ackerbau.
1994
Basedow T. | Poehling H. M. | Lauenstein G.
By adding 11 new field experiments, the control threshold for non-viruliferous cereal aphids attacking winter wheat, developed on the base of 36 experiments in the FRG (Basedow et al. 1989), was adapted to the new economic conditions of agriculture. The optimal growth stage of wheat for controlling non-viruliferous Sitobion avenae (F.) and Metopolophium dirhodum (Walk.) is the end of flowering (EC 69). Applications of insecticides against cereal aphids during heading (EC 55) or before did never result in increased yield. One experiment of the old series, with significant loss of yield in spite of a very low level of aphid attack, was eliminated now, since comparison with a higher number of experiments was possible. Some of the new experiments (Fig. 3-5) illustrate the difficulties of forecasting cereal aphid attack. Deducted from 44 experiments, carried out from 1980 to 1992 from Kiel to Mainz, the optimal control threshold proved to be four aphids per ear and/or flag leaf of wheat, at the end of flowering (EC 69). This threshold is valid for the current conditions. An attack of 65% of ears and/or flag leaves is equivalent to the 4-aphid-level. This control threshold should be used only in the areas where it was established, and in areas of comparable climatic conditions.
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