A leading independent agronomist is saying that farmers must be prepared to hit black-grass hard wherever and whenever they can in the rotation and this means using the residual herbicide Kerb Flo in winter oilseed rape when conditions are right.
Agronomist Seumas Foster says that, if you have resistant black-grass on the farm, you can not afford to mess about. "Some of my farms have RRR resistant black-grass, but are not always able to achieve commercially acceptable results only using cultural control options such as stale seedbeds and delayed drilling, so as part of a planned programme the use of Kerb is important. They can introduce some spring cropping but peas and/or beans don’t offer the same level of profitability as rape and can interfere with the rotation."
"Successful oilseed rape crops need to be established early and well. If you have difficult black-grass, it is essential that it is tackled hard across the rotation and in oilseed rape that means a full scale herbicide programme starting with a pre-em herbicide such as Novall, Shadow or Centium, followed by a post-em contact graminicide such as Aramo for volunteer cereal control, and finished off with post-em residual Kerb with Laser and oil. In my experience Kerb works very well against black-grass and we can get 100% control, even of RRR resistant black-grass."
Seumas advises that these high levels of weed control can be attained with Kerb when it is applied at the right time under the right conditions and at the right dose rate. "The best conditions for Kerb are a firm clod-free seedbed which encourages shallow germinating black-grass, and wet and cold soil conditions at application, although we have seen significant results on large tillered black-grass if the roots are in the soil surface. Dow AgroSciences make it easier for us by providing helpful information on soil temperatures and moisture deficits, as well as on tank-mixing and best practise when it comes to water protection."
David Barratt of Nugent Farms contract farms for Nick Spence at Maddle Farm, a neighbouring farm, which uses Seumas Foster for agronomic advice. He also supports the use of Kerb, saying it is a very useful and effective herbicide. "The soils here are chalky downland with a high pH and the usual cropping includes wheat, spring barley and winter oilseed rape. The main weed problems we have to deal with are black-grass and cleavers, with sterile brome on the headlands. Our black-grass has become more and more difficult to control in the last few years and most has both enhanced metabolism and target site resistance, so it is a real challenge."
"With such a challenging problem we have to take a programmed approach, using stale seeds beds and a number of herbicide applications in crop. I see Kerb as an essential part of that programme. It has no known resistance problems and it works really well. It needs to be used correctly though and we take strict notice of all the label recommendations and conditions of application. In particular the soil temperatures are important. These need to be declining, with the target temperature of 10°C. The residual life of propyzamide is much longer at these lower temperatures," points out David.
"Although our chalkland has few ditches or streams, we take every care to avoid any problems with water pollution. We are very conscious of avoiding application if the soils are waterlogged or heavy rain is imminent. We also take application seriously, making sure that boom heights are optimised along with all other aspects," says David Barratt.
Robin Bentley of Dow AgroSciences emphasises that, hand in hand with good advice on how to apply Kerb correctly, comes good advice on minimising the risk of water pollution. "It is vital that everyone - farmers, advisors and manufacturer - plays their part in keeping this valuable herbicide out of water, so that its future is secure and that it can continue to be used as an essential tool in the armoury against black-grass and other grass-weeds and in resistance management."
In the last two years Dow AgroSciences has undertaken two major studies that look at the pathways by which propyzamide can move from treated land into water courses.
The Allerton Project indicated that surface water run off can account for 20% of the propyzamide that might be lost and that buffer strips can significantly reduce the potential for that route to reach water courses. Work at Cockle Park, Newcastle’s University Farm further investigated this pathway and also looked at the significance of drain flow and how three different establishment techniques: min-till (down to 10 cm soil depth), partial inversion (down to 22 cm soil depth and full inversion (> 30 cm soil depth) can effect movement down to the drains. The results showed that establishment technique does have an effect on reducing the movement into water, with min-till showing the best effect.
"This is new information and so we will be working with agronomists to leverage this knowledge in the best possible way. It is research work such as this plus the tailored support from agronomists that ensures we continue to develop the best recommendations for use for this molecule and so help steward and safeguard its future," says Robin.
"By using Kerb Flo or other propyzamide products from Dow AgroSciences, advisors and growers know that they will be positively supporting and investing in a wide-ranging and on-going Stewardship Programme. It is important to reflect on this this autumn when you are faced with the choice of a cheap generic alternative," Robin Bentley concludes.
