Difficult season prompts increased weed threat Arable farmers across the west of the UK need to pay particular attention to weed control after the recent spell of prolonged dry weather has limited the effectiveness of pre-emergence residual herbicides. That is the advice from Dr Simon Pope of Wynnstay Arable who believes that many beet, maize and winter and spring cereal crops may be at an increased risk of weed infestation following an uncharacteristically wet autumn and dry spring. Last year’s autumn rains meant that many farmers were simply unable to apply pre-emergence herbicides as the ground was too wet to travel.

As a result, large areas of crops were left untreated until spraying could commence following the arrival of drier spring conditions.

However, those spring conditions, which have been uncharacteristically dry for an unusually long period, have now presented an increased risk of weed ingression. On many farms, particularly those with lighter soils, the ground could be too dry for residual herbicides to work effectively. As such weed protection could be severely compromised.

“Where growers were able to apply residual herbicides during the autumn, we have seen some stunning levels of weed control,” Dr Pope observes. “However, for a significant proportion of farmers, this wasn’t possible and we have had reports of some real weed control headaches in a variety of different crops.

“Annual meadow grass in particular is causing a major problem for barley growers, especially those that are growing varieties that aren’t tolerant to CTU usage. For these growers, there has been very little they could have done cost effectively this spring to control meadow grass if the autumn residual was missed.”

The advice from Wynnstay’s arable team is therefore to check crops regularly to tackle new weed emergence. “It isn’t safe to assume that residual herbicides applied during the spring are going to provide the normally expected levels of weed control this year,” Dr Pope explains. “It is likely the lack of moisture in the ground may have already limited the effectiveness of these herbicides.”

Anybody that is in doubt about how to tackle weeds during this abnormal season is advised to check their fields to see if any tidying up is required. Under the current conditions more reliance must be placed on contact acting herbicides. “If any weeds have sneaked through they should be taken out with a suitable herbicide as soon as possible to avoid any crop competition,” Dr Pope concludes. “Doing nothing is not an option as this could result in some very mucky crops which will suffer from reduced yields and will be difficult to harvest.”

Further information from: Dr Simon Pope ,Wynnstay Arable Tel: 01939 210555

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