An evaluation of the potential benefits and costs of autumn-sown sugarbeetin NW Europe

In NW Europe a major limitation to the yield of sugarbeet is development of the foliage canopy in May and June, too late to capture much of the availa ble solar energy. This problem could be solved if the crop was sown during autumn so that the seedlings survived the winter and developed a large leaf canopy in early spring. This has led to a search for mechanisms to control flowering so that plants remain vegetative after the winter. However, ther e has been no serious attempt to estimate the effect of advanced canopy dev elopment on the likelihood of water stress. This study has used a combinati on of modeling of growth to predict yield of rainfed crops and an analysis of the literature to examine the likely consequences for pest and disease i ncidence if autumn sowing could be achieved without bolters. Compared to sp ring sowing, a potential yield advantage averaging 26 % could be achieved, but this is likely to be overturned by any one of several beet-specific pat hogens. For example, beet yellows virus would become more difficult to cont rol and this has the potential to halve yield. Downy and powdery mildew and beet cyst nematode would be more expensive to control. The change from spr ing to autumn sowing would not allow harvest to be significantly earlier; t his would be prevented by dry, strong soil conditions. Nevertheless, the in creased emphasis on autumn work on arable farms would be costly.