With the spring weed control season fast approaching, we asked Bayer what are the most frequent questions growers put to their technical hotline?
Perhaps not surprisingly a lot of the questions the Bayer technical hotline staff receive are concerned with specific product details – how and when to use them.
Herbicide portfolio manager Ben Coombs says: “Often it is things which are on the label but the caller wants to confirm they have understood correctly or perhaps they have a slightly unusual situation where they need some additional guidance. Apart from the product-focused questions, we get asked about weed growth cycles, pest identification, nozzle choice and all sorts of other things.”
Tank mixing and the effect of weather on plants and herbicides are common questions. Tank mixing is one of the more complex areas for questions because there are so many potential tank-mix combinations.
“Our basic advice in this area is to keep mixes simple. Make herbicide applications in early spring, then follow up later with T0s because you will get better activity from herbicides and fungicides if you apply them separately.
“There may only be a few percentage points variation in control but it does make a difference, especially for herbicides like Atlantis because it is the last chance to treat black-grass before harvest.”
Of course, this standard advice sometimes comes under pressure when conditions on-farm are testing with limited spray days and wet ground, so another question is ‘what to do then’?
With any combination of products going into the tanks there are three main questions to consider, says Mr Coombs:
Balancing crop safety, efficacy and efficiency is the aim when opportunities to spray are limited – lookout for tank mix sheets for herbicides, which list a range of different products which are safe to mix.
“We often get asked about chlorothalonil, because farmers are understandably tempted by the idea of including it with Atlantis to get a head start with their fungicide programme; however, Bayer advise against this mix because the two products do not interact in a beneficial way.
“We have also been asked about micronutrients and post-em herbicides – once again we would not recommend using them because they may reduce herbicide performance and micronutrients can be safely included at other applications during spring,” says Mr Coombs.
See also: New tool in black-grass armoury
Residual herbicides also raise questions, the main point to stress is that applying residual herbicides in winter cereals at this time of year is to deal with any spring-emerging grass-weeds – it is not to treat what is already there. There is a caveat in that diflufenican provides some control of grasses pre-tillering but the general point still stands.
“The main weather question we get asked is if it is warm enough to spray? As a rule of thumb if there is active growth in the target weed then it is the correct decision to treat. A good barometer is the grass on the lawn – if that is growing then it is likely that grass-weeds in fields are growing as well,” says Mr Coombs.