Weed control programs in sugar beet (Beta vulgaris L.): Influence on herbicidal residue and yield quality

The objective of this study was to compare different weed control programs and to evaluate their effect on herbicidal residue and quality parameters of sugar beet root. Field experiments were conducted during a three-year-period from 2008 until 2010 on arable fields located in south-western Poland. Chemical weed control in sugar beet was carried out by herbicides including substances such as phenmedipham, desmedipham, ethofumesate, metamitron, triflusulfuron and multicomponent adjuvant applied in four different programs. Determination of quality parameters, sugar, K+, N+ and N-alpha-NH2 content in roots of sugar beet, was done by automatic analyzer VENEM A IIIG. Residues of herbicides were detected using HPLC/UV. In soil samples. where herbicides in the oldest program (pre- and post- single-application at full doses) were applied, the sum of all detected residues of applied substances amounted to 0.0198-0.0575 mg.kg(-1). The application of herbicides in newer programs (split-application at reduced doses and micro-rate application) resulted in decrease of residues about 36.54 and 80%, respectively. The decrease of residue level according to programs was statistically significant. In sugar beet root samples, the residues of active substances were lower than in soil. The same tendency as for soil samples was observed. Sugar beet root quality parameters were not affected by the herbicide treatments. Results obtained from treatment objects were not significantly different to untreated and hand weeded checks.