Early weed control key to spring cropping success

Good seed-beds and early weed control will be top priorities for arable growers as they swing into spring cropping after some disastrous autumn drilling stories.


Tighter controls on some herbicides will add a further headache to those still reeling from the large amount of undrilled wet land left over the winter.


Brian Ross, technical manager at Frontier, cautions growers not to force crops into a poor seed-bed as they bid to get something into the ground.


Growers are urged to consult advisers to check on herbicides available for use this spring with some products unavailable due to tighter controls.


“Cultural controls and pre-emergent herbicides should be top of people’s priorities with a number of products being withdrawn and there simply being fewer options for growers to stay one step ahead,” Mr Ross told Farmers Weekly.


There have been a number of changes to rules covering the Extension of Authorisation for Minor Uses (EAMU) for herbicides this spring and growers are advised to check with advisers.


Spring barley


Spring-sown barley suffers less severe weed challenges, but growers still have worries concerning withdrawn products, weed resistance increasing and blackgrass.


Stephen Moss, Rothamsted weed scientist, believes that pre-emergence herbicides will be important this year and moist soil conditions will help them in their efficacy in targeting blackgrass.


He notes that making the most of a pendimethalin mix or Avadex will be worthwhile with there being limited products for use post-emergence.


“Spring barley is generally more competitive, so it is important to get it off to the best start possible to make life easier for yourself,” says Dr Moss.


“You are very limited in the post-emergence products, but Axial offers good control of wild oats which people have taken out with other sprays in previous years and deemed it not a problem.”


Senior weed consultant at the Scottish Agricultural College, Mark Ballingall, believes many spring barley growers will be considering meadowgrass as the weed they need to target as it is becoming more and more significant over the years.


“There will be more about this year and aside from the yield affect, it can soak up moisture and reduce the number of combining days as well as having implications for drying as it tends to retain a lot of moisture.”


Mr Ballingall believes the increased amount of minimum tillage systems operating across the country may be a factor in the rise in meadowgrass.


An EAMU for Liberator at 0.3 litres/ha in spring barley has given growers a useful tool for targeting the weed, he notes.


“You’ve still got Stomp Aqua as an option which you can use pre-emergence or go for the Defy or Hurricane approach.


“Flufenacet works slightly better on a drier seed-bed than Stomp, which is quite useful. Often at spring barley drilling time when the seed-bed is dry, pendimethalin needs moisture to work; Liberator is more active under dry conditions because it is more soluble,” he says.


An issue that appears to be raising its head is sulfonylurea resistant chickweed and poppy which requires a change in tactics.


“An application of 1 litre/ha of Spitfire offers different chemistry or you could add Tomahawk or Starane to the sulfonylurea,” he says.


Another important weed that growers will need to be wary of is fumitory with a good rate of Headland Saxon in a mix with a sulfonylurea offering the best protection, according to Mr Ballingall.



Linseed


Linseed looks set to see a resurgence in popularity this year with technical manager at United Oilseeds Richard Elsdon noting growers will have to take extra care in their choice of sprays with many available being on EAMUs.


“Most of the graminicides can be used on linseed which is fine when it comes to wild oats, but there are a few difficulties with graminicides and blackgrass.”


Mr Elsdon believes a disinfectant approach using glyphosate will offer the best start.


“Then I would be looking at using 15kg/ha of Avadex post-drilling and rolling. The benefit of Avadex is it has an effect on range of broad-leaved weeds as well as knocking the blackgrass seriously and doing a good job on wild oats.


“There’s a wide variation for broad-leaved sprays with half of them on EAMU’s, so the grower would need to check on those,” he says.


Mr Elsdon says a common approach of half-rate Jubilee followed about 10 days later with half-rate Eagle is fairly effective and economical.


“When we look at the slightly more expensive options, which may do it in one hit, you’ve got Chekker.”


Chekker is a post-emergence product combining some broad-leaved and grassweed control and can be followed up by a graminicide.



Spring beans


There are limited herbicide options for beans so getting the correct programme with what’s available will be critical in this coming spring season.


Frontier’s Mr Ross has urged growers to be wary of the threat of polygonums, or broad-leaved weeds, and the importance of staying on top of them following a bout of cold weather and heavy frosts.


Mr Ross believes a full rate of 4.5 litres/ha of Nirvana offers the greatest control.


“It’s good on polygonums, but is rate responsive on them so you have to keep the rates quite high.


“Linzone is also quite useful if you mix it with pendimethalin. You can’t put a lot of linuron on, but what there is, is effective,” he says.


Mr Ross noted growers must be aware that when using pendimethalin under EAMU, it would need to be mixed with something as you are unable to get enough on, on its own.


There are some farmers who have got Skirmish on farm and although that product is going to be restricted they are able to use it this year.


“A mix of Skirmish with either of Nirvana or Linzone to try and eke out what could be a shortage in certain products this year.


“If you’re going to go with Skirmish, the rate is usually a 1 litre/ha, but if you want to eke things out, try 0.5 litres/ha of Skirmish plus Linzone at 1.5 to 1.75 litres/ha.”


Growers are very limited in what is available to them post-emergence, with Basagran being the only product available for beans.


“You can split it or go with a full rate of 1.65kg/ha. Its weed spectrum is limited, but where you may have mayweeds or charlock, it’s a good product to be used. You do have to be mindful of the beans being waxed up enough though,” he says.