It’ll not be long before growers turn their attention to autumn establishment
With harvest underway, it’ll not be long before growers turn their attention to autumn establishment – all with the ultimate goal of giving their winter crops the best possible start. Here, arable editor Dominic Kilburn asks three technical experts what their key priorities are for good crop establishment.
We are now in an age where agrochemicals can only get us so far, warns Northants-based AICC agronomist Damian McAuley, as he considers what the priorities are for growers establishing winter crops this autumn. There are now so many regulatory restrictions on what can be used, coupled with increasing incidences of resistance, that we simply can’t rely on working out of a can, he warns.
“We are still in the tail end of the wheat/rape/wheat/rape culture, which has brought on many of the problems associated with product resistance, weed control difficulties and yield plateauing, and so my main message to my growers this autumn is that they must start to be more prescriptive in how they go about planning next season’s rotation, and those beyond,” he comments.
“It sounds basic, but decisions must be made more on a bespoke, field-by-field basis. The right crop must be selected for the right field and I don’t believe we can think in terms of large block cropping any more.
“We must be more flexible this autumn. So, for example, if you harvest a crop of oilseed rape and discover a carpet of black-grass underneath, then consider changing that field to a spring crop,” he advises.
Varieties and seed rates
For lighter land this autumn look for more drought-tolerant varieties and those which have vigorous early establishment to compete with grass weeds, Damian continues, pointing out that varieties with high yielding ability should be matched to land that can deliver that potential.
“Seed rates must be sufficient to be competitive against grass weeds although on kind land these can be pulled back particularly with OSR hybrids,” he comments. “Think about every field – if a crop of OSR is alongside a wood where pigeon damage is likely, then increase seed rates in that part of the field,” he suggests.
“After drilling, and especially if you have black-grass, it’s a case of roll the seedbed and roll it well – whatever the crop. It will improve crop germination, emergence and early vigour, as well as suppress pests and weeds and it will also assist the efficacy of residual herbicides.
“If sub-casting OSR it’s critical you roll well, especially with flea beetle in mind and early crop vigour is essential to get away from it,” he adds.
According to Damian, flea beetle is now the ‘Sword of Damocles’ hanging over oilseed rape growers with plenty of crops damaged earlier this season due to the lack of protection. He suggests that a starter fertiliser containing nitrogen and phosphate would be a useful addition to the crop at drilling to give it that all-important boost. “Get the crop up and away as soon as possible – it’s critical now that the protection from neonicotinoids has gone. Monitor crops this autumn and use an approved pyrethroids spray if required while watching out for signs of resistance.
“Keep an eye out for slugs too – choose a long-lasting pellet and keep baiting points up,” he advises.
While he understands the concern some growers have over delayed drilling, Damian says that it’s a matter of prioritising known bad black-grass areas. “Trials data and experience shows that we get better control of black-grass when we drill in October. If you’ve got too many acres to wait until October then be strategic – field-by-field. There is a definite improvement in delaying and the residual herbicides used at pre-emergence will work better in the (more likely) available moisture.
“Think about the specifics of crop drilling – the date and the situation in the rotation: if it’s early then protect the seed against BYDV with Redigo Deter (prothioconazole + clothianidin); if it’s late then a single purpose seed dressing; for a second cereal think about Latitude (silthiofam) for take-all; when following roots then Austral Plus (fludioxonil + tefluthrin) for wheat bulb fly.
“Don’t compromise on seedbed and establishment,” he stresses.
All in a day’s work
Only drill as much as can be rolled and sprayed in the same day, highlights Damian, who says that even if it’s relatively dry, the risk of waiting for moisture and then not being able to get on due to bad weather is too great. “Post-emergence black-grass control is so limited and so it’s vital to get the pre-emergence herbicides on soon after drilling.
“It sounds obvious but whether you are a small one-man band business, or a larger farming enterprise, the principle remains the same.”
Where a spring crop is planned for this coming season, Damian suggests that a cover crop in the ground over winter is better than leaving land fallow. “Cover crops look after the soil, managing soil moisture, preventing nitrogen loss as well as fixing it too. Their roots are powerful cultivators and soil conditioners helping to provide good conditions for crop rooting.
“Get them in as early as you can after harvest – like any crop, they need to be established well and the longer they are in the ground the more benefits they will bring,” he adds.
Damian says that he is seeing a reduction in black-grass populations where cover crops are used – the black-grass germinating within the cover crop and then burnt off with it in the spring. With minimal soil disturbance the priority to prevent further black-grass germination, ideally the spring crop should then be direct drilled.
“A cover crop allows you to leave the soil from the autumn to the spring in the best condition possible,” he adds.
Whether it’s establishment of wheat or oilseed rape – black-grass control must be the key focus this autumn, says LW Vass (Agricultural) and Bedfordshire-based agronomist Andy Scott.
Recent hot and dry weather has coincided with black-grass seed senescence and this should induce short seed dormancy, he suggests. “In theory, this should mean quick germination and the opportunity to spray it off as many times as possible prior to sowing.
“I think rotational ploughing is the long-term solution for better black-grass control but, where it’s possible this season, it may be better not to bury the seed and go for quick germination with a post-harvest movement of soil of between 2.5-3.0cm.
Andy says there is no opportunity to delay OSR drilling because of the flea beetle threat and the need to get the crop up and away as soon as possible.
He suggests that quick establishing varieties such as ES Alienor and Alegria will have a part to play and that growers should consider these types of varieties carefully.
“As a guide, increase OSR seed rates by about 1kg/ha and add about 30kg/ha of seedbed nitrogen to boost establishment,” he advises.
“My main concern for quick establishment is to get away from flea beetle but it’s also important that the crops can get away well in the spring too and be competitive with any remaining weeds,” he adds.
Andy says that earlier this season, OSR crops in the region suffered a 30 per cent total loss, much of it blamed on flea beetle as slow establishment in the dry conditions last autumn left crops vulnerable to attack. “If flea beetle pressure is high, it’s important that any decisions on early herbicide applications are made once growers are confident that they have a crop that is going to establish.
“The metazachlor-based herbicide options are recommended either pre-em or post-cotyledon, but applying pre-em may prove to be expensive if the crop establishment fails. There may be a slight compromise on weed control with the post-em application but better not to have spent #40-#100/ha applying a herbicide early, only to lose the crop and then be saddled with following crop restrictions when a change in cropping is required,” he explains.
Like the advice with OSR, Andy suggests that seed rates for winter wheat should be kept up and vigorous early tillering varieties such as JB Diego, KWS Target and Croft selected to help smother and out-compete black-grass.
“Delaying drilling however is probably the most important of all cultural control methods in the armoury to tackle the black-grass threat and if you can’t get a crop in the ground because of the weather later in the season, it’s better to have lost the opportunity to grow wheat infested with black-grass and switch to a spring cropping option.”
Referring to the late drilling that took place last autumn, he says that for those sowing wheat at that time everything came right with warm, 200C temperatures being more than ideal for good establishment.
“Rolling straight after drilling is important too – consolidate the seedbed and retain the moisture to provide a sensible surface for the heavy loading of residuals to come,” he continues.
“Aim for an accurate drilling depth of 32mm and avoid an open and cloddy seedbed otherwise there is a risk of seed damage from the pre-em applications, particularly following heavy rainfall.”
Andy says that Avadex (tri-allate) is probably the key product of choice at pre-emergence, followed either by Crystal (flufenacet + pendimethalin) or Liberator (diflufenican + flufenacet) at, ideally, the 2-leaves stage of the crop and 1-leaf of black-grass. This will allow a BYDV spray to be incorporated with the Crystal/Liberator to save a pass, he says, reminding growers that the latest applications should be made at 3-leaves of the crop (2-leaves black-grass) for maximum efficacy.
“If conditions are dry then you could reverse the applications and go with Crystal/Liberator first, followed by Avadex which is prone to volatilisation in warm and dry conditions and is readily broken down. Also consider the addition of Lexus SX (flupyrsulfuron) to the residual ‘stack’ to add additional percentage points to the level of control but be aware of the restrictions for use in sequence of other SUs and ALS inhibitors.
“Last season I employed double stacking virtually wall-to-wall on my black-grass-prone wheat crops and we have seen very good levels of control, but timing is critical, and, where some got it wrong, the results are not so good,” he says.
“I had to use very little Atlantis (iodosulfuron + mesosulfuron) in the spring this season and did not have any black-grass-infested wheat sprayed off with glyphosate, but all of the cultural and chemical control methods, and timings, need to come together this autumn if growers are to get the black-grass control results they are looking for,” he adds.
AICC and Arable Alliance Nottinghamshire-based agronomist Andrew Wells reckons that with crop margins looking pretty thin on the ground at the moment, and non-existent in many cases, there is some uncertainty among growers as to which crops and varieties to grow, let alone the best way to establish them this autumn.
“In terms of oilseed rape I think there will be more farm-saved seed going in the ground this year as a way of reducing costs but there are areas which are plagued with flea beetle and so the overall area is likely to drop and, as a result, could offer other growers an opportunity,” comments Andrew.
“Our area here in the East Midlands however didn’t see a lot of flea beetle last autumn and it wasn’t a major problem, so we’re hoping it isn’t this time around,” he adds.
In the absence of neonicotinoid seed treatments, Andrew also says that a tight and fine seedbed with moisture is so important when drilling oilseed rape; rolling it twice to really consolidate the surface if possible, he stresses, emphasising that good seed-to-soil contact will aid faster establishment and give flea beetle less places to hide.
“An addition of phosphate just before, or at the time of, drilling will help get the crop to that 3-leaves stage where it becomes a little safer from flea beetle attack,” Andrew advises.
While delayed drilling is key for grass weed control in wheat, he points out that it doesn’t mean moving your wheat drilling date from mid-September to the first week in October. Drilling must be delayed towards the end of October to make a real difference to black-grass control, he says.
“As a consequence, think a little more about the type of drilling equipment to use later in the season when soils are more delicate – some heavier drills with press wheels are not really suited to late season conditions.
“Some will only delay to around the 7th-10th October but it’s not enough to achieve what you want with stale seedbeds. The challenge is still to get multiple killings prior to drilling,” he says.
“Seed rates will be higher because of delayed drilling, so that will result in a higher cost to growers, but it will create better crop competition against weeds,” he adds.
“If there are delays at that point in the season, then growers can turn to the fast developing winter wheat variety Belepi, or a spring wheat such as Mulika, which have a wide sowing window from early November onwards. If you can drill them in late autumn then that’s fine, but they are both equally adept at being drilled as late as early April,” he explains.
“These types of varieties are looking very good in the ground so far this season,” suggests Andrew.
Finally, he reminds growers that the pre-em herbicide mix must be robust, however, while that factor alone is not going to solve the black-grass problem, it’s a key consideration as part of a ‘whole approach’ to grass weed control.
Establishment priorities at a glance:
– Plan rotations carefully to maximise weed control options- Be prescriptive on a field-by-field basis- Delay drilling wheat where possible- Keep seed rates up to compete with grass weeds- Use varieties with known autumn vigour- Roll seedbeds after drilling to retain moisture, encourage seed germination and help in the defence against flea beetle attack in OSR- Ensure pre-em herbicide applications can keep up with the drilling programme – Timing of pre-em herbicide applications is critical for success against black-grass- Switch to a spring crop rather than establish a poor wheat crop late in the autumn- Consider a cover crop ahead of a spring crop for soil conditioning and additional weed control