In response to the challenges so far this season Dow AgroSciences is supporting farmers with advice on how to optimise their herbicide programme in winter wheat in the fight against blackgrass and other grassweeds.
According to the latest Grassweed Emergence Monitor, grassweeds will be small coming into the spring.
Dow AgroSciences’ cereal herbicide specialist Stuart Jackson says: "This year kicks off with continued challenges like many backward crops, crops having not received planned residuals last autumn and a lot of winter wheat yet to be drilled."
"GEM is geared to help growers understand when to apply treatments. It highlights one positive in a difficult year: the slow emergence of blackgrass will result in smaller plants in early spring."
Jackson says there has been a high level of blackgrass seed return and protracted blackgrass emergence so there is still an opportunity to build in a residual spray between now and the end of the month. He recommends farmers should apply it as soon as possible if they get the chance.
"As we’ll see smaller than normal grassweeds in the spring there is a fantastic opportunity for grassweed control with pyroxsulam-based products, like UNITE or Broadway Sunrise, when there is onset of active growth. In the absence of blackgrass Broadway Star is a more cost effective option for many grassweeds. The benefit of additional broad-leaved weed control is an additional advantage from all three pyroxsulam products" he adds.
Those fields that have received an appropriate autumn residual herbicide (pre-emergence, peri-emergence or post-emergence) can be followed up in the usual way with UNITE + adjuvant +/- additional residual upon active growth of the target grassweed.
Winter wheat drilled in January or early February can be treated pre-emergence and then followed up with UNITE+ residual + adjuvant at two to three leaves of the blackgrass.
The use of additional residual with UNITE should be considered when applications are made during January and February especially where blackgrass is small and there is a concern with subsequent emergence.
Jackson says where CTU is applied post-emergence farmers should ensure there is an interval of at least four weeks between the CTU and an application of any product containing pyroxsulam.
If farmers have missed autumn residual appropriate residual grassweed sprays can still be applied as soon as conditions allow to manage the grassweed populations.
Where it has not yet been possible to apply a residual herbicide and active growth is evident, Mr Jackson advises farmers apply a tank mix of a residual product + UNITE + adjuvant.
In a season of late herbicide use and stacking, cumulative effects of actives on following crops – in particular oilseed rape – may be a concern.
“One benefit of pyroxsulam is that it is rapidly degraded in the soil and residues will not persist to affect following crops such as oilseed rape or beans. UNITE has no cultivation restrictions prior to sowing following crops,” says Jackson.
GEM has been used together with feedback from customers, the Dow AgroSciences hotline and Regional Business Managers to ensure these recommendations can be issued.
"These services are geared to ensuring successful use of products through the critical periods of the year," says Jackson.
"However this advice represents practical approaches in response to the difficult conditions being experienced on farms. It is a compromise on the advice for optimum control in a more typical season but we’re aiming to provide the best solutions possible to help agronomists and farmers."
