Herbicide residues' changes in wheat samples in late weed control

Since the change of the Hungarian agriculture the increased weed infection causes great losses in wheat. It is necessary to apply herbicides on the weedy field as harvest approaches to make the harvest easier and avoid losses. In our small plot trials at Nagygombos, between 1996 and 2002 the applicability of fluroxypyr, bromoxynil, dicamba, tribenuron-methyl and MCPA in late weed control was examined in four wheat varieties. We found that the late application against weeds did not have a total eliminating effect, however reduced the number of weeds, restricted their development and the reproductive organs below and above ground dried. Weed seed infection was slowed down and the dried stems made harvesting easier. In the last three years, we found that fluroxypyr (Starane) and tribenuron-methyl (Granstar) impeded a little the maturing and water extraction in the milk maturation stage of wheat, but this difference was not seen in full maturation. Examinations showed that after late weed control, all of above-mentioned chemicals except bromoxynil (Pardner) was discharged at the time of the harvest and were under the maximum residue tolerance limit. So the experimentally involved herbicides can be used for late weed control - in accordance with international experiences.