Reduktion des Pflanzenschutzmitteleinsatzes - Konsequenzen für das Schaderregerauftreten und die Wirtschaftlichkeit in Getreide-Zuckerrübe-Fruchtfolgen

Abstract

The discussion about the application of crop protection chemicals in recent years has led to the initiation of the "Program for the Reduction of Plant Protecting Chemicals." This demands that the use of plant protecting chemicals be limited to a level that is necessary. The necessary level is defined here as the most economical measure of infestation relative to the products that are applied for plant protection. In the realm of this work the possibilities of reducing the use of plant protecting products as well as the economic and biological consequences were thoroughly analyzed, starting with the current state of the art of crop protection product application. In 3 years of field trials this analysis of problems was done under conditions which approximated real conditions as much as possible, so that the results can be transfered into agricultural practice. The second part of this work examines how much the hardiness of specific varieties of winter barley and winter whe at may allow a reduction in the application of fungicides. Additionally the influence that the ploughing, or the not ploughing, that it has on wheat was examined relative to the likelihood of succumbing to disease, resulting in a need for fungicides. The application of plant protection products according to good professional practice showed the safest insecticide, herbicide and fungicidal effects and it also showed the highest yields. By applying expert knowledge and prognostic models in contrast the application of plant protection products over crop rotation was reduced by 35 %. While the reduction was uneconomical for sugar beet, the reduction for grain led to slight gains in comparision to current practice. On the other hand, a reduction of crop protection product use by one half of that used in current practice led to unsatisfactory results, as seen from a biological and economic perspective. Complete elimination of pesticides led to severe economic losses and is therefore unrealistic for competitive agriculture. By planting more resistant varieties it was possible to reduce the application of fungicides by about 25 %, especially for winter wheat, whereby the total application of plant protection products was reduced by only 5 %. In fungicide trials with wheat and barley it was demonstrated that up to two thirds of antifungal products could be saved when using more disease resistant varieties. The tests also show that it is difficult to determine the optimal application of fungicide for specific varieties. For winter wheat, after non-ploughing soil preparation, 45 % more fungicide of the expert version was applied because of the necessary protection against Drechslera-tritici-repentis. The use of pesticides in agriculture is an area of contention that will continue to require dialogs in the future, dialogs between ecological interests, the protection of the environment, and the need to achieve economical production.