Crop-wild interaction within the Beta vulgaris complex: agronomic aspects of weed beet in the Czech Republic.

Abstract

AbstractThis review is focused on weed beet in the Czech Republic (Central Europe). In our conditions, beet is quite a new weed. Weed beet has occurred more frequently since the end of the 1980s when beet seed started to be imported from southeastern European countries. By the beginning of the 1990s, about 50% of fields used for sugarbeet production had already been contaminated by weed beet. Nowadays, the infestation of many fields used for intensive sugarbeet production is already so high that it is impossible to grow sugarbeet in them. The growth habit of weed beet varies significantly from plagiotropic to orthotropic forms and from large to small root bodies. Our observations have shown a high degree of variance of morphological traits between localities as well as within populations. Genetic variability was high and unstable in all populations. This was due to different hybridizations between weedy and cultivated beet in different geographical localities where the seed was produced. Seed testing is an important method for the prevention of weed beet spread, and every year some seed lots with weed beet contamination higher than the permitted 0.05% can be found. In these cases, seed production companies have to pay the farmers for the additional costs of weed beet control. As a direct control method, hand pulling can still be used, especially on fields with low weed beet infestation. When higher levels of infestation occur, mechanical hoeing can be used, but weed beet plants survive within the crop rows. Chemical control using non-selective herbicides can be highly effective. Current control systems do not provide sufficient weed beet suppression in sugarbeet fields as the conditions of intensive sugarbeet crop production seem to favour the introduction and spread of weed beet. New management tools for effective control of weed beet populations are expected with the introduction of GM herbicide-tolerant sugarbeet cultivars. However, it will also be very important to study the influence of the agronomy and the cropping systems on the dynamics of the weed beet complex in order to quantify and limit gene flow from transgenic beet to weed beets.