Occurrence and control of insects in wheat in the south of Lower Saxony
1992
Bartels, M. (Landwirtschaftskammer Hannover, Northeim (Germany). Fachbereich Pflanzenschutz)
The density of cultivation, the high level of yield and the necessary nitrogen fertilizer are responsible for the intensive attack of winter wheat by insects in the south of Lower Saxony. Considering the corresponding economic threshold, aphids have to be controlled nearly every year. These thresholds can't be used if yellow dwarf virus could be transmitted in the follow of mild winters or if strong and continuous by Metopolophium dirhodum is found beneath the leaves. In 1989 and 1990 we had a strong attack of yellow dwarf in early sown winter wheat infested in autumn and in early spring, but additional to this all winter wheat was infested in May and at the beginning of June. The loss of yield was considerable, also because of the late infestation. Haplodiplosis equestris can be observed every year too. This insect appears especially in rotation with frequent wheat cultivation. The three fields rotation of sugar beet or rape, winter wheat and winter barley seems to be less endangered than a rotation with wheat dominating. On dark and similar soils Phorbia coarctata causes damage in late sown winter wheat. Resolidifying of the seed bed seems to be a suitable preventive measure. In very endangered fields the additional insecticide treatment of the seed reduces the damage
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