The effects of timing and dose on the control of Galium aparine (cleavers) and other broadleaved weeds by fluroxypyr in cereal headlands.
Experiments were carried out in headlands of winter cereal fields to investigate the effects of timing and dose of fluroxypyr for control of Galium aparine on a range of other species. In the first year, fluroxypyr was applied at 200 g a. i./ha, at four dates in the spring (March-May). A treatment with mecoprop (one application date only) was included for comparison. In the second year fluroxypyr was applied in December, March, April or May at doses ranging from 70-200 g a. i./ha.
In the first year, high levels of G. aparine control were achieved with fluroxypyr at all timings, reaching 100% in April. Fluroxypyr was more effective than mecoprop applied on the same date. In the second year control of G. aparine by lower doses was also highest in April, but earlier applications at higher doses also gave good control. Other species responded in different ways, but highest levels of control generally resulted from April treatments. Spring germinating species were unaffected by applications made before April.
It is concluded that, where it is desired to retain some broadleaved weeds as part of a ' conservation headland' strategy, early application is preferable. Conversely, where the aim is to maximise weed control, treatment in April gives the best results.