September drilled wheat on land with grassweed problems will likely need a follow up spray during October, warns Bayer’s Gareth Bubb. “It doesn’t really matter which herbicide or combination you’ve used at pre-em; it will likely run out of steam during October,” he says.
On the back of two difficult seasons, effective weed control in cereals is more important than ever. Early October is the peak germination period for black grass, Italian ryegrass and many other weeds in cereal crops. Irrespective of drilling strategy, achieving good control with herbicides is a priority he notes.
“If you went with Liberator (flufenacet + diflufenican) + Proclus (aclonifen) at pre-em, cinmethylin-based products are a possible option at early post-emergence. Personally, I think cinmethylin fits better because it should work well and have better crop safety in that slot than as a pre-emergence spray.
“If you have already used cinmethylin, an alternative, is metribuzin-based products. I like these because they have some contact activity and they’re also good on broadleaf weeds, which would help prevent some of the problems we saw last spring. In particular, I’m thinking of weeds such as mayweed, groundsel, pansies and speedwells.”
This top up application could also coincide with a spray against aphids transmitting barley yellow dwarf virus – but use one of the various tools to help judge risk.
For October drilled wheat crops, Gareth’s advice would be Liberator + Proclus because of its broad spectrum of activity and persistence. “You can then add in other products depending on risk of crop damage and what you are trying to control, most likely prosulfocarb and tri-allate,” he adds.
In annual meadowgrass plus broadleaf weed situations, he suggests it is viable to wait until growers see the rows before applying any herbicides. In those scenarios, the metribuzin-containing products are a step ahead of the flufenacet / DFF products.
“You can either use the metribuzin products either alone or you can mix them with picolinafen / pendimethalin or chlortoluron-containing products to give a really broad range of weed control. Alone I would keep the rates up, but in mixture you could drop the metribuzin product rate down to 0.5 L/ha.”
