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December 2002. Papua New Guinea asked an interesting question about the withholding period for herbicides. The Ramu Sugar Limited use fusilade (0.75 litres product/ha) to control grass weeds in cowpea fallows. Is it likely that there will be any chemical residues left on or in the plant after a week before the plants are used as a vegetable. There are withholding periods for insecticides, but what about herbicides?
In response, PestNet members advised that Meister publications (US) recommends a maximum application rate of 0.375 lb a.i./acre for fluazifop-P-butyl, the active ingredient in Fusilade (as distinct from Fusilade 2 which has half the concentration of a.i.). The rate used in Papua New Guinea (0.165 lb a.i./acre for Fusilade) is much less than the above.
Yes, there are withholding periods for herbicides, too. These vary according to the compound, concentration, application frequency and crop. It is best to check the manufacturers’ information on each product. In the case of Fusilade this is provided at:
www.syngenta.com.au/Start
The USEPA (United States Environmental Protection Agency) website might provide or lead to more information.
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