A key herbicide that cereal growers believedwas lost for good is making a comeback in a new product offering early controlof meadowgrass and problem broad-leaved weeds.
As part of Makhteshim-Agans (MAUK)commitment to position and market products responsibly, Tower will be supportedby the companys Water Aware initiative.
Chlorotoluron had been used until recently,either alone or with diflufenican, at rates of up to 3500g/ha to controlmeadowgrass, broad-leaved weeds and other grass weeds in cereal crops.
It was withdrawn from sale as a straight in2010 and three years later as a co-form, due to a lack of data to support lowerapplication rates that would pass the aquatic risk assessment, part of theregulatory process.
Following extensive research and investmentby the company, revised rates and timings have enabled the active to beresurrected in Tower, a new product that contains 250g/litre of chlorotoluronplus 300g/litre of pendimethalin and 40g/litre of diflufenican.
At the recommended rate of 2 litres/ha,Tower delivers 500g/ha of chlorotoluron which, with the partner actives,provides excellent control of meadowgrass and a range of broad-leaved weedswhen used early in the season, says Paul Fogg, senior crop team lead at MAUK.
Tower offers a simple, standalone solutionto growers across 60% of UK cereal area for which meadowgrass, rather thanblack-grass, is the main grassweed target.
Its proven residual activity also controlskey broad-leaved weeds, notably poppy, chickweed and mayweed affected byincreasing resistance to ALS chemistry. Other weeds controlled includeshepherds purse, red dead nettle, speedwell, pansies and cleavers, he adds.
Tower can be used on winter wheat, winterbarley, winter rye and winter triticale. For this first season of use, it canbe used early post-emergence at growth stage 10-13. The product may not be usedafter the end of October and also carries an aquatic buffer restriction of 9m,although this is reduced to 1m at the top of a ditch that is dry at the time ofapplication.
A revised assessment will be submittedusing Drift Reduction Technology 3-star LERAP nozzles to mitigate the aquaticbuffer, says Dr Fogg. Further label developments will be introduced to makethe product as flexible as possible for farmers.
We are acutely aware of the legacy issuessurrounding chlorotoluron and surface water. Our development plan for theactive substance included a critical review of the agronomic drivers andenvironmental legislation, in particular an assessment on the impact of theWater Framework Directive.
As part of the new Tower label we havebrought application timings forward and away from the high-risk period thatcoincides with heavy late autumn and winter rainfall. The earlier timing alsomeans we are tackling meadowgrass pre-tillering when plants are small.
Although there are currently varietyrestrictions, trials so far indicate no adverse effects on winter barley pre-orpost-emergence, and no significant effects pre-emergence on wheat. Further workis needed to assess performance post-emergence on lighter soils, says Dr Fogg.
The same product is marketed in Germanywhere it has been possible to remove variety restrictions. We are hoping thatwe will be able to get to a similar position in the UK.
Tower illustrates MAUKs aim to preserveactives responsibly by taking a comprehensive view of the market and analysethe commercial, agronomic and regulatory pressures to see how they might fit inwith modern agronomic needs, says Dr Fogg.
We can ill-afford to lose any moreactives, he adds. With Tower, we have ended up achieving the same result asolder formulations of chlorotoluron in terms of meadowgrass control by doingsomething a bit different.
This has satisfied the regulatoryauthorities and helped to fulfil our aim of keeping proven solutions availablefor farmers.