Great Claims made for grassweed herbicide

By Mike Abram

CEREAL GROWERS look set to benefit from a new pre-emergence/early post-emergence grassweed herbicide this autumn, which will not carry any drilling depth restrictions and to which there is no known resistance.

Official approval for prosulfocarb will be considered at the May meeting of the Advisory Committee on Pesticides, with first sales hoped for next autumn, says Syngenta”s Alison Bosher.

From the same thiocarbamate group as Avadex (tri-allate), prosulfocarb is already on sale in most other EU countries as a post-emergence graminicide treatment, but has been developed to control blackgrass and ryegrass pre-emergence in the UK , in tank-mix with a suitable partner.

“Recommendations will be tailored for the weed present. Against blackgrass we will be recommending 4 litres/ha prosulfocarb + 2 litres/ha trifluralin, while for ryegrass the partner will be 2 litres/ha of chlorotoluron.”

 In trials, the blackgrass combination gives similar control to market leading pre-emergence product Crystal (flufenacet + pendimethalin), but with less variability in performance, she suggests. “Growers can be more confident of the response they are getting.”

 With no known blackgrass resistance to prosulfocarb or trifluralin, it will provide a solid start to control programmes, she adds.

Prosulfocarb + trifluralin is also kinder to the crop than Crystal, suggests Syngenta technical manager Iain Hamilton.

Crop effects were still being observed in May in crop safety trials following double-rate Crystal applications, particularly where crops were shallow drilled, and irrigated, simulating rainfall following application to a less than perfect seedbed. “It is not uncommon to see effects with Crystal if seed bed quality is not as good as it could have been.”

 In contrast, no effects were seen with prosulfocarb, he says. “There should not be any limitations on drilling depths.” That should remove growers” current concerns about using a pre-emergence product, such as Crystal, when seed-bed conditions are not good enough, adds Ms Bosher.

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