United Kingdom
September 23, 2014
Yorkshire farmer Nigel Durdy has had RRR black-grass resistance confirmed on some of his land and is adapting the way he farms to minimise the problem and increase his chances of controlling this weed. He also suspects that he has ALS resistant poppy and possibly chickweed, but is less concerned about these as there are effective alternative herbicides that he can still use.
“On one of the farms that we contract farm, we have had to adopt a tight crop rotation of oilseed rape, wheat and wheat. The soil is a heavy boulder clay and crops have been established by min-till for quite a few years now. So you could say that we have built up the black-grass resistance problem ourselves, but I wanted to know the type of resistance we had, so that I could decide what to do next,” says Nigel.
He reports that “the black-grass came back with RRR resistance to most things – Atlantis, fops and dims. Without this specific information we could easily be wasting our time and money on products that simply would not work. Knowing the resistance status helps in our decision making and longer term planning.”
Mr Durdy says that the owner of the contract farm wanted to keep a tight rotation, but he explained that there needed to be a change of heart as weed control was becoming so difficult. “So we now do several different management approaches that we hope will help. The first is that we avoid min till and try to move the soil around quite a bit. As soon as the crop is harvested and straw removed, we work the land to a depth with a subsoiler. Then we go in 7 to 8 inches deep with a Solo and then press down to make a good seedbed. As soon as possible we use stale seedbeds, at least 2 times and hopefully 3 times with glyphosate.”
“The second approach is that we delay drilling. Wheat is delayed until the end of September. I daren’t go any later. Thirdly we have dropped the second wheat and replaced it with forage rye destined for a local anaerobic digester. Forage rye is drilled in September and harvested in July, so it buys you valuable time at the end of the season to cultivate and use stale seed beds before the rape goes in. Giving yourself more time can really help. For this reason I wouldn’t consider growing forage maize as it is drilled in the spring and is harvested too late,” says Nigel.
Nigel also thinks that he may have resistant broad-leaved weeds. “Several fields with light land have a horrendous poppy population and I suspect that this may be a result of ALS resistance. I am less concerned however, as there are alternative herbicides to ALS that will control poppies in both wheat and rape. In rape for example AstroKerb (propyzamide and aminopyralid) will control poppies. I also suspect chickweed resistance on some sandy soil but again I will avoid ALS herbicides such as metsulfuron and use something else.”
Louis Wells, Agronomy Manager for BASF, has helped Nigel sample his weeds and made suggestions to manage his resistance problem. “We have sampled poppies on the farm and have sent them to Germany for resistance testing. Results are available early spring. But, as Nigel says, there are alternative herbicides such as Stomp Aqua (pendimethalin) for use in cereals or Shadow (quinmerac, metazachlor and dimethenamid-p) in oilseed rape that will control these weeds. Nigel is making useful changes to the way he farms which should help. It is always useful to stand back and realistically assess what you can do to minimise weed resistance, by changing cultural practices as well as making different choices in the chemical armoury that you have.”
AstroKerb contains propyzamide + aminopyralid. Atlantis contains iodosulfuron-methyl-sodium + mesosulfuron-methyl. AstroKerb is a registered trademark of Dow AgroSciences. Atlantis is a registered trademark of Bayer CropScience.
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