14 September 2001

OSR herbicide shortage set to increase weeds

TEMPORARY shortages of oilseed rape herbicides mean there could be more weedy crops about next season.

Metazachlor-based products Butisan and especially Katamaran have been hard to come by recently, says ADASs David Parish.

"It is a big concern. They are the main pre-emergence and early post-em products, and we probably need a bit more than usual this year as more growers find they have difficult blackgrass."

Metazachlor is useful where blackgrass is already resistant to fop and dim herbicides, he explains. "But metazachlor is much less effective once the weed gets past the two-leaf stage."

Bob Mills of Banks Cargill confirms the shortage, particularly of Katamaran (metazachlor + quinmerac), which is most widely substituted for Butisan (metazachlor alone) where cleavers are expected to be troublesome.

"Id say about half the farms I see that had planned to use it have had to go for an alternative."

Kent farmer Robert Spencer reckons BASF should cut prices to reflect the product shortfall.

"Its only 75% effective post-emergence, and I reckon the price should reflect that."

Poorer poppy and cleaver control means he will no longer be sowing a planned seed crop at Lower Garrington Farm, near Canterbury, Kent.

Diane Lovesy, BASF product manager, disagrees saying that 90% control can be achieved post-emergence, provided growers are not tempted to cut dose.

She blames extra oilseed rape sowings for the temporary shortage. "We had anticipated a 5% increase, but feedback suggests there could be 5% on top of that." That would put this seasons crop at 350,000ha.

Alternatives for growers still planning pre-em treatments include Centium (clomazone) with trifluralin or Butisan, says Mr Mills. "Butisan plus Centium should be just as good as Katamaran. It works out a bit more expensive, but if needs must…" &#42

OILSEED RAPE WEEDS

&#8226 Pre-em herbicide shortages.

&#8226 Difficult blackgrass concern.

&#8226 Post-ems less effective.

&#8226 Alternatives more expensive.