3. Managing competition between cultivated plants and weeds by cultivation methods and selective use of herbicide 3.4. Studies on competition and increase of weed in a rotation with winter wheat, winter barley and sugar beet
1994
Schumann, H. (Bonn Univ. (Germany). Lehrstuhl fuer Speziellen Pflanzenbau und Pflanzenzuechtung)
To determine influence of differently terminated application of underseeds and herbicides on weed competition and increase in winter barley and its following crops sugar beet, winter wheat and sugar beet two year field experiments at two locations in the Rhine area are carried out in crop plant populations varied by genotype, seed rate and nitrogen management. Comparing the effects of similar treatments in winter wheat, winter barley and sugar beet different weed control strategies for the rotation, including underseeds as a mean of suppression of weeds, are valued using the criteria yield loss in the single culture and the population dynamics in the rotation. The amount of competition in mixed stands results from the competitive power of weed and crop plant. This is influenced by weed's growth mass and composition of species and by cultivation system of winter barley. Strong stands of two rowed barley varieties are able to suppress weed plants. Possibility of compensation of competition is given by crop plant's density- and nitrogen-management. A low effect of cultivation methods seeding is determined by success of weed control. Increased seed content by lasting weeds produces following weeds, which can be proofed to the third following crop. Because of the sensible stages to weed competition of winter barley and winter wheat after EC25 and sugar beet after 6 leaves and because of early seeding weeds and their carry over in the rotation weed competition has to be removed early for avoiding yield losses and following weed surely. With underseeds as an alternative form of weed control, dependent on species and sowing date, interference can be produced, which suppresses weed but not crop plant
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