Which spring crops are best for blackgrass control
Which spring crops are most competitive against black-grass?
Spring barley is one of the most competitive spring crop choices, while spring linseed is considered to be the worst.
Sugar beet also fares badly for competitiveness, especially early in the season, when black-grass numbers can be overwhelming, note agronomists.
“The problem with sugar beet is that it needs to be drilled early on heavy land, if yields are to be maximised and the crop can be lifted in good time,” says Steve Baldock of Prime Agriculture.
“In this situation, even with the use of mechanical and inter-row chemical weeding, black-grass in the rows can be a major problem.”
Spring barley is more competitive than spring wheat, notes independent agronomist Andrew Cotton of Cotton Farm Consultancy. “But you can get very good results from spring wheat, even when sown in April. The same is true of oats, which have tremendous tillering ability.”
Oats are also known to produce avenocins, which act as an antagonist to black-grass germination in the following crop, he adds.
“Dense crops are best, so they all need sowing at high seed rates. Oats can produce a really thick, compact crop.”
Spring oilseed rape is another choice which can be very competitive, with an April sowing date allowing multiple black-grass flushes. “Again, it’s best to avoid low seed rates, so hybrids may be less suitable.”
Spring beans work well providing plant populations are kept up and they aren’t drilled too early. “Gaps in crops should be avoided, as black-grass loves them and is happy to fill them in.”
However, none of the above crops are competitive enough to cope with vast numbers of black-grass, warns Steve Baldock of Prime Agriculture. “The weed numbers must be reduced before drilling.”
Which spring crops are easiest to grow when trying to reduce black-grass populations?
In general, most spring crops will grow well, although there is less room for error due to their shorter growing season.
“They are drought prone and don’t like soil structure issues,” says Steve Baldock. “Get fertility, soil structure and soil conditions right, and forget about the calendar date.”
That means waiting until soils are dry enough before drilling, he advises.
Provide the same attention to detail and investment as you would a winter crop, as they will respond well to inputs, he adds.
Specific advice includes avoiding peas on soils prone to waterlogging and maize on sloping ground, where possible.
“Be aware that spring wheat tends to have a later harvesting date, and may suffer from lower yields where drilling gets delayed.”
Which spring crops are most likely to be profitable when you have black-grass in the rotation?
Yield will make all the difference to the profitability of a spring crop.
“There’s more uncertainty about profitability at the moment, given forward pulse prices and current barley pricing,” notes Steve Baldock.
However, growers shouldn’t ignore the black-grass and yield impacts on the rest of the rotation, he adds. “Wheat grown after peas or beans will always yield more than after oilseed rape.”
For spring beans, very high yields of around 7t/ha, together with human consumption quality, will prove very profitable. Likewise, spring barley and spring wheat averaging 9-10t/ha will be among the best performers on any farm.
However, peas drilled late on waterlogging prone soils will struggle to get to 2t/ha, he warns.
Andrew Cotton notes that multiple spring crops in the rotation are likely to reduce profitability – especially where more costly establishment techniques are used - but their inclusion may be necessary to get back to sustainable, low seed bank farming.
“A return to more profitable rotations, with spring crops in, is the aim. There are plenty of farms where this has already been achieved and they now have viable, long term farming systems.”
Based on previous performance and average yields, spring barley is likely to top the profitability league, closely followed by spring wheat and beans. Oats come next, then peas. Spring oilseed rape and linseed bring up the rear.
What plant populations should you target for a spring crop drilled to help against black-grass?
The later that a spring crop can be drilled; the more likely you are to get good black-grass control.
However, this has to be balanced with the need to get yields, to maintain profitability, and the increased likelihood of drought later on in the spring.
Drilling date is less important than soil condition, agronomists stress. “Ideally peas should be in by the end of March, but if they will still get up and going quickly by delaying for a week or so, then wait.”
Beans are less fussy, but compaction should be minimised. For both spring linseed and oilseed rape, daytime soil temperatures need to have reached 5C before drilling takes place.
Andrew Cotton points out that thick crops are essential where black-grass is an issue. He works to the following plant population targets, which are largely based on ADAS work:-
Spring oats: aim for 375 plants/m
Spring wheat: aim for 325 plants/m
Spring barley: aim for 325 plants/m
Spring oilseed rape: aim for 150 plants/m
Spring linseed: aim for 400 plants/m
Spring beans: aim for 40-50 plants/m
Spring peas: aim for 65-70 plants/m
What herbicide options do you have for controlling black-grass in spring crops?
The herbicide options for grass weed, particularly black-grass control in spring crops are limited, although both spring wheat and spring barley have more choices than others.
Diflufenican 0.2 L/ha – pre or early post emergence – EAMU Authorisation numbers: 20121500, 20121801, 20141269, 20121457, 20121242, 20130140, 20141266
Stomp Aqua up to 2.9 L/ha – pre or early post emergence – EAMU Authorisation number: 20092910
Defy up to 5 L/ha – pre-emergence only- EAMU Authorisation number: 20131477
Avadex 15kgs – pre-emergence only - EAMU Authorisation number: 20140462
Axial up to o.6 L/ha – to GS41
Topik 0.125 L/ha – to GS41
Atlantis 0.4kg/ha – crops must be sown before February 1 – EAMU Authorisation number: 20082946
Stomp Aqua up to 2.9 L/ha – pre-emergence
Avadex 15kg/ha – pre-emergence
Liberator 0.3 L/ha up to GS24 – EAMU Authorisation number: 20121010
Crystal 2 L/ha up to GS23 – EAMU Authorisation number: 20130951
Diflufenican 0.125 L/ha – best efficacy pre-emergence
Defy 3.0 L/ha up to GS13 – EAMU Authorisation number - 20131373
Axial up to 0.6 L/ha to GS41
Spring Oilseed Rape
Butisan 1.5 L/ha – pre-emergence
Centium 0.25 L/ha – pre-emergence
Laser 1 L/ha + oil
Stomp Aqua – up to 2.9 L/ha
Centium 0.25 L/ha
Aramo 1 L/ha
Laser 1 L/ha
EAMU information correct as at 7 October 2014
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