Waging chemical warfare on farm pests and weeds
The ever-dwindling range of permitted chemical treatments on agricultural land means careful use of products and strict observance of the rules is vital.
Sprayer operators met for an expert briefing at the DKB Crop Protection headquarters in Walworth, near Darlington. They are working towards their certification by the National Register of Spray Operators.
Regulatory expert Alison Clayton told the meeting that glyphosate had been re-approved for a five-year period, and it was crucial that chemical stewardship principles were followed in order to minimise the risk of a potential ban before the agreed date.
“It is possible that we will lose glyphosate, at least as a pre-harvest option for killing weeds.
“If glyphosate is being used as a pre-harvest aid, it must only be applied when the grain or seeds show a moisture content figure of 30 per cent or lower. Weeds should only be targeted when they are green, healthy and actively growing.”
The issue of glyphosate resistance had been identified across the globe, and it was believed that a handful of cases had been identified on UK farms, she told delegates.
“Glyphosate has been commercially available for four decades, and resistance to the chemical has recently been found in sterile brome and blackgrass,” she said.
“Options for reducing the risk of glyphosate resistance include adopting a varied rotation, using cultivations to kill off weeds and the application of products with alternative modes of action, as well as cultural control.
“Ideally, no more than two applications should be used within a single season, and weeds should be targeted at the optimum growth stage, and with the chemical at the correct dosage.
“Another recommendation is laboratory testing of sample quantities of surviving seeds to help identify whether there may be a problem with resistance.”
Meanwhile, Diquat was only licensed for sale or purchase until this May, with stocks having to be used up by February 2020, she said. Like all the other products which were due to be withdrawn from the market, excess supplies would need to be removed by a licensed waste contractor.
The ban on neonicotinoid seed treatments for outdoor crops had hit the industry hard, commented Miss Clayton, leaving few alternatives for the control of barley yellow dwarf virus and as a means of reducing slug populations. Later drilling could help to offset the loss of neonicotinoids.
Metaldehyde pollution was considered a high risk in the Teesdale area and nationwide, and it is predicted that metaldehyde products will be withdrawn within the next six to eight months, with use-by deadline expected in mid-2020, she said.
“Until the cut-off point, metaldehyde must be used responsibly,” she said. “It is essential that baiting points are used, to check whether the slug population has reached threshold numbers.
“A fine, firm seedbed will deter slugs, as the adult molluscs find it easier to move around in large clods, especially in wet soils.
“A field buffer zone of tenmetres should always be adopted when using metaldehyde and these areas may benefit from an alternative product such as ferric phosphate as a treatment.”
She urged all operators and arable farmers to carry out an inventory of their chemical stores.
“It is worth double-checking that products are being managed according to guidelines. Stores may contain active ingredients that are due to be banned and that are not likely to be utilised by the specified end date.
“It might be beneficial to collaborate with a neighbour, as the correct route for disposal can be expensive. Potential savings could be made by joining with a fellow farmer and organising one collection, instead of two separate transactions.”
Miss Clayton also urged operators to check locations before spraying by visiting the Environment Agency’s “Check for Drinking Water Safeguard Zones and NVZs” web pages. Entering the farm postcode would bring up a map highlighting any areas which fell into the two categories. (The facility was previously listed under the heading, “What’s in your Backyard?”).
Anyone intending to spray crops within the designated areas might also find it useful to follow the guidance in the water advice section on the Voluntary Initiative website, she added.