Yield of winter wheat influenced by the interactions between crop management measures and take-all

Abstract

With higher proportions of winter wheat in the crop rotation, up to monoculture, the risk of yield losses due to take-all increases.In 1983-84 and 1984-85 the influence of crop management measures (preceding crops, sowing date, cultivar and seed rate) on the development of take-all during the growing season (at main tillering (GS 25), stem elongation (GS 31), flag leaf just visible (GS 37), ear emergence (GS 51), milk ripening (GS 75) and maturity (GS 91)) and the yield of winter wheat was investigated in field trials in NW Germany.Starting at a low level after winter, take-all infection slightly increased until ear emergence. After GS 51 the proportion of diseased roots increased greatly and reached its maximum at harvest time in all treatments.The preceding crop (wheat or oilseed rape) and sowing date (mid-September or late October) had the greatest influence on take-all, whereas the disease of roots was less affected by cultivar (Disponent or Vuka) and seed rate (200, 400 or 600 kernels m-2). In both years and at all assessed stages, wheat after wheat sown in mid-September was most infected by take-all, whereas wheat after oilseed rape sown in mid-September and wheat after wheat sown in late October showed similar disease ratings. The crop management system not only influenced the extent of the disease, but also the reaction of the plant to an infection. After wheat, all yield components measured were reduced by increasing take-all ; after oilseed rape, only thousand grain weight decreased.To avoid early take-all infection resulting in heavy yield losses, it is suggested that the seeding date of wheat be delayed until end of October, especially after a previous wheat crop.