“Business as usual” for heavy land black-grass control The black-grass battle lines are being drawn ahead of autumn drilling.
With the end of harvest in sight, Dominic Kilburn talks to two heavy land agronomists ahead of the new season’s opening gambit against ever-threatening black-grass populations. Cultivation, drilling, crop competition and herbicide strategies all come into focus. Overall, black-grass control has been better however ‘hotspots’ on farms continued to appear, said North Essex-based AICC and Samco & Shrim Farmers’ agronomist Jamie Mackay, reflecting on the past season. “On the whole, we didn’t get those large areas of black-grass in crops that subsequently had to be sprayed off, as was the case in the spring of 2016. “We used Hamlet (mesosulfuron + iodosulfuron + DFF) to get on top of autumn populations, which worked well, additionally we were fortunate with sufficient moisture last October and November, which helped the residuals, and because it was so dry in September and the forecast was good, even the larger farms delayed a good proportion of their drilling until well into October.”
Cultivations and drilling While rotational ploughing will appeal to some of the larger units
Jamie advises on, ploughing into second wheats or ahead of a spring break crop for example, he said that many of his heavy land growers won’t plough at all and pay particular attention to developing good stale seedbeds and using glyphosate to maximise black-grass kill ahead of drilling. “They will go through with tines, or discs and rolls to create a stale seedbed although in practice it’s not easy to move just the top 2in of soil. “With moisture levels currently (mid-August), they should be looking for sequences of two or three hits with glyphosate between harvest and drilling wheat. “In many cases it’s a question of achieving some sort of stale seedbed after harvest to start with, and then spraying glyphosate as and when flushes of grass weeds appear,” he said. “This year may not be quite so straightforward in terms of
persuading growers to drill late but we will still earmark later drilling where possible. “At the moment it looks like we are going to have to manage some wet soils, although that could change in a month. However, because of the unsettled weather we are having, growers might be adopting a slightly more cautious view this autumn and look to start drilling around the 20th September,” he suggested.
Crop competition Typically, he recommends seed rates of between 350–400 seeds/m2 in mid September and 450–500 seeds/m2 moving into October. “There are varieties such as Santiago, which is robust and produces a thick canopy, or Elgar, which is tall and competitive, and these types of varieties will help to compete with black-grass, but upping the seed rate and selecting a variety that suits the farm and the conditions is probably more important.” Also helping with blackgrass control is the fact that growers in the area have shifted from a traditional five-course rotation – featuring wheat/wheat/OSR/ wheat/winter oats or winter beans – to one where the fifth crop features spring barley or spring oats. “Some of the newer oat varieties have good lodging resistance and, with their resistance to take-all, they certainly have potential as a spring crop option for our growers,” pointed out Jamie. “It’s certainly a challenge to produce good yielding spring crops
on this land and good drainage, which is almost a forgotten area, is a key aspect of course,” he added.
Herbicides Flufenacet, pendimethalin and DFF continue to be a core herbicide treatment in the autumn, however trials work he undertook with Samco & Shrim colleague Matthew Paterson highlighted that increasing the standard dose rate of flufenacet (240g ai/ha) to 360g ai/ha, with the addition of Defy (prosulfocarb), made a difference in the level of black-grass control achieved. “We’ve also been trialling sugar beet and herbage herbicide ethofumestate, as in Xerton, and it looks promising. It provided us with similar, or better levels of control as Avadex but with the benefit of costing less. “Ethofumesate brings a little bit more to the table but you must be careful how you use it as it can be a bit ‘hot’ on the crop. “It’s approved as a post-em product on winter wheat and can be a timely addition to a later-applied insecticide spray tank mix.”
Business as usual For Northants-based AICC and Indigro agronomist, Damian McAuley (left), the story for effective black-grass control hasn’t changed. “The situation is simple – it’s business as usual for black-grass,” stressed Damian. Key to cultivations and preparing the ground for a seedbed, is to get them done as early after harvest as possible and then leave it, he advised. “Where fields are relatively clean, then use shallow cultivations, although strategic use of the plough in problem areas is useful. But if you can get away continued over...
www.farmersguide.co.uk September 2017
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