Early use of OSR herbicides essential Growers are being warned once again to adhere to best practice advice regarding oilseed rape herbicides this autumn, or risk losing them altogether. Dominic Kilburn attended a briefing held by stewardship group Metazachlor Matters. Oilseed rape herbicides containing metazachlor should be applied as early as possible to crops this autumn to reduce the risk of surface water contamination as well as help safeguard their use on farm for the future. That is the main message from stewardship group Metazachlor Matters which is trying to raise awareness of the issues, particularly to growers in central areas of the country, in ‘Safeguard Zones’ where river catchments are vulnerable to pesticide exceedances. The stewardship group, which was developed by crop protection companies BASF and Adama three years ago as part of a Europe-wide initiative, has re-issued its guidelines for metazachlor-based herbicide applications: For drained fields in higher risk areas identified as Drinking Water Safeguard Zones, products should be applied by the 1st October; Outside of those zones applications can be made until the 15th October, providing soil and seedbed conditions are good and drains are not flowing; Where there are no drains then there are no restrictions.
Later application concern BASF’s head of business development and sustainability, Rob Gladwin (right), representing the Metazachlor Matters initiative, said that it’s key that growers and agronomists are aware of the potential risk to surface water if applications are made slightly later in the season. About 60– 70 per cent of oilseed rape herbicides are going on in September, a figure which was expected, he said, but he suggested there is a movement of applications from pre-emergence to post-emergence. “There is a trend for moving aplications from pre-em to post-em due to the agronomic challenges being faced by growers and to when investment in weed control is justifiable – and this offers the potential to increase the risk of herbicides into water.” Stewardship advice is to apply the products early, and onto well structured seedbeds, where the
herbicides do their job and then breakdown, minimising the risk of movement to water later in the season. “Get the agronomy right by applying metazachlor early – before the 1st of October on drained land – and stewardship will follow,” Mr Gladwin stressed. He highlighted that, as well as metazachlor, which was applied to about 60–70 per cent of the OSR area, co-component in OSR herbicide programmes quinmerac, was also coming under scrutiny of the regulators and increasingly being seen as a risk. Growers being made aware of how these actives perform in the soil is important he suggested and, while metazachlor is moderately mobile in soil, quinmerac’s persistence in the soil and mobility is high. “Metazachlor Matters has been running for two seasons now and the trend of metazachlor being found in water is going the right way, despite there still being some exceedances, but water companies are now also looking for quinmerac routinely and seeing increasing levels. “The product is coming more into focus and where metazachlor is applied, quimerac is usually too and this highlights the challenge we are facing,” he added. Mr Gladwin said that going back a number of years there had been a lot of finger pointing regarding the problem (and cost) of pesticides being found in water and while there remained no ‘silver bullet’ solution, organisations were working together, and with individual farmers, to focus on the issues. “We advise growers and agronomists to go to the Voluntary Initiative (VI) for the best practice advice – for yard and field activities. Both theses factors are important in terms of how OSR herbicides get into water.” Also at the event was Adama’s technical specialist Kuldip Mudhar (right)and he reiterated that the overall message regarding OSR herbicides remains the
same: “Metazachlor is the baseline treatment and if we don’t look after it we will lose it,” he said. “With the August early drilling trend we are seeing for oilseed rape, most growers will naturally be applying a post-em treatment sufficiently early, which is good news. “But getting metazachlor on before drain flow is the key message,” he added.
Catchment management Severn Trent Water catchment manager Dr Jodie Rettino (left) said that her company was trying to work with as many as 500 farmers in catchment areas for the rivers Leam, Avon, Stowe and Itchen across the Midlands. She said that Seven Trent Water was very practical about pesticides but highlighted that ‘catchment management’ was about reducing pesticide peaks in water by 50 per cent. “We have a monitoring system in place that is looking for hotspots of metazachlor and quinmerac, and we can see the issues,” said Dr Rettino, who explained that the business had to close down a water treatment works for two weeks when quinmerc was found in the reservoir at two times the drinking water standard. “We estimate about £40 worth of quinmerac had found its way into the reservoir and it cost us £150,000 to treat. “It’s very dificult to remove quinmerac and it’s not cheap to do so,” she added. According to Dr Rettino, Severn Trent Water has been working with the VI and Catchment Sensitive Farming for many years and it continues to introduce schemes to help engage with farmers. One, called the Severn Trent Environmental Protection Scheme (STEPS), match-funds farmers up to £5,000 if they engage in options such as constructing biobeds and biofiltres on their farms, or other initiatives to reduce pesticide issues. To date, across its region, 284 applications to the scheme have been made by farmers since its launch in 2015. Other schemes, although currently only related to issues with slug pellet active metaldehyde, include funding farmers
for the difference in cost between metaldehyde-based pellets and wate friendly ferric phosphate based products, as well as a scaled ‘clean water payment’ for farmers of up to £8/ha where water up and downstream of their farm is tested for metaldehyde. “Our clean water payment is currently focused on metaldehyde but it’s a transferable scheme that could be applicable to metazachlor and quinmerac,” she pointed out.
Measured response Jim Reeve (right) farms a range of soil types at the 534ha (1,300 acre) Newfields Farm, Long Itchington in Warwickshire, which borders six miles of the Leam and Itchen rivers. Some light land with irrigation is let for vegetable production while 60ha (150 acres) of heavy boulder clay provides the other extreme. Typically, 300ha (740 acres) of wheat are grown, predominetly for milling and contracted to Warburtons, as well as 100ha (250 acres) of oilseed rape. In addition, this season, 40ha (100 acres) of cover crops were drilled. According to Mr Reeve’s agronomist, Agrii’s Andrew Richards (right), oilseed rape is the most important crop on the farm. “While this year we have seen a lot of rain, soils on this farm can be droughty, and oilseed rape is the most reliable crop,” commented Mr Richards, who has advised on the farm for 30 years. “As well as being reliable, it provides an early entry for following crops,” he added. Prinicpal weeds on the farm include black-grass and meadow brome, as well as broad-leaved weeds such as poppy, cranesbill, cleavers and mayweed. “When you consider the weed spectrum, metazaclor and quinmerac are vital tools on this farm and it’s in our interest to maintain these products as best we can,” Mr Richards stated. continued over...
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