Make the most of residual-acting propyzamide
Propyzamide is recommended in winter oilseed rape from the 1st of October onwards, but Interfarm UK who market two formulations, Engage and Flomide, are advising growers to make sure that they know how to get the best from this residual herbicide whilst handling it with care when it comes to water issues.
"UK arable farmers are facing a challenge when it comes to grass-weed control as we are potentially losing two popular herbicides, IPU and trifluralin. Meanwhile weed resistance is widespread. Earlier this year trifluralin did not make Annex 1 and, despite IPU successfully gaining Annex 1 in the EU, a local decision was made in the UK not to support this residual because of problems in water courses resulting from farm usage. The focus of the legislators may shift to other popular residual herbicides, not just in cereals but in other crops. For this reason it is important that farmers know how to get the best from these other residual herbicides and also to understand the behavioural characteristics of particular compounds so that risk of water pollution is avoided. Protection of water is a major issue and a major threat nowadays. It is a case of use it properly or you run the risk of losing it, too," says Dr. David Stormonth, Technical Manager for Interfarm UK Ltd.
Dr Stormonth explains that propyzamide is very different to IPU as it binds tightly to soil particles and does not leach. "This physical characteristic allows effective control of grass-weeds in the top inch of the soil and no deeper. It also means that propyzamide does not get into land drains when applied properly. But the one circumstance that could result in this product appearing in water courses is when fast surface run-off is allowed to carry soil particles from fields down the tramlines, particularly in wet autumns. All measures and application techniques should be taken to avoid this happenstance."
"With a reducing choice of herbicides, it is also important that growers use the remaining ones to their maximum effect. For propyzamide this means applying it when soil moisture is good and in cooler weather. Soil temperatures need to be low so that long persistence is achieved throughout the weed germination period and good levels of soil moisture are needed to help the herbicide penetrate the top layer of the soil profile. This year as black-grass and rye-grass germination will be protracted, it is important that the residual activity of propyzamide is enhanced. Seedbeds need to be fine and firm as reasonably possible. Crop canopy should not be overly developed so that there is good soil coverage from the spray application," says David.
"Propyzamide also controls all strains of black-grass and rye-grass, with no resistance having ever been identified despite many years usage. Because of the widespread nature of black-grass resistance and the need for a long-term strategy across all crops, the integration of Engage, a WP formulation of propyzamide, or Flomide, a flowable formulation, into an effective black-resistance management plan is essential these days. It is more important than ever to use good actives in break crops as problems in controlling black-grass in cereals escalate," advises Dr. Stormonth.
"Propyzamide has a wide window of application of four months, from 1st October right through to the 31st January and there is plenty of opportunity to use this key active when conditions are conducive to its best performance. Understanding how this herbicide actually works, the best conditions for its performance and how to handle it with care will mean that growers will not be disappointed and the herbicide will be around for a lot longer yet," says David.
Propyzamide is available from Interfarm as Engage (50% WP), (which has been rebranded this year from Propose), and Flomide (400g/L SC). Both are recommended in winter oilseed rape, winter beans and a wide range of other crops for the control of cereal volunteers, annual meadow-grass, black-grass, brome, wild-oats, chickweed, bindweed, fat hen, redshank, small nettle speedwells and black nightshade. In oilseed rape, Engage is recommended at 1.4 kg or 1.7 kg/ha and Flomide at 1.7 l/ha or 2.1 l/ha. Use the high rate for black-grass control. Engage and Flomide are compatible with pyrethroid insecticides, graminicides and relevant fungicides including Quell Flo (mancozeb).
