As the warmer weather approaches and fertiliser applications are made, the spray window for the control of cleavers in winter oilseed rape opens and growers need to be ready to apply their post-emergence herbicide. Galera (clopyralid and picloram) is the main spring-applied herbicide due to its high level of performance and its weed spectrum which includes cleavers, mayweeds, creeping thistles and sow-thistle. It must be applied before the latest date of application which is when flower buds are visible above the crop canopy.
“Cleavers in oilseed rape are the most aggressive weed when it comes to competitiveness, impacting yield and significantly decreasing percentage oil content. They also cause problems with admixture in the grain and are a problem when seed is returned to the soil, increasing the cost of weed control in the arable rotation. Cleavers can also grow through the crop, along with thistles and mayweeds, and interfere with the combine, increasing harvest costs. With the disappointing price of rape at the moment, growers need to minimise any action that will lead to a lower price such as lower oils and unacceptable admixtures as well as any action leading to increased costs such as interfering with machinery at harvest and increasing down time,” says David Roberts of Dow AgroSciences.
“The weather is warming up now and crops are receiving their spring fertiliser. This means that many crops will be approaching application time, so I would advise growers to take the opportunity they have to get ready to apply Galera. For consistent and reliable performance, it should be applied when the soil temperature is 6oC and rising. The warmer and more stable conditions, the better the results are likely to be, particularly against cleavers. It also should be applied to a dry leaf and it needs 6 hours drying time. A breeze to dry the plants off in the morning and a planned application during the warmest part of the day is the approach most likely to give good results. That is why having the appropriate fields identified and the required amount of Galera on farm and ready to apply is so important,” says David.
“Galera will control cleavers and mayweeds up to 150 mm in size, sow-thistles and creeping thistles up to 4 leaves or 50 mm in size and groundsel up to 6 leaves. Groundsel is appearing more and more in the arable rotation and, although not on the label, it will be well controlled by Galera. If cleavers are not a problem, but sow-thistles, thistles and mayweeds are, Dow Shield 400 will do a great job,” he says.
Care should be taken when assessing crop growth stage in particular signs of stem extension. The cut-off stage for application of Galera is when flower buds are visible above the crop canopy, he says.
David advises growers to check their Galera MAPP number as there are two different labels out in the market this spring. “The positive news is that Galera has gone through the more rigorous re-registration process successfully and so will continue to be available to UK growers in the future. Existing stocks of Galera, with the MAPP number 11961, can be used up until the 30th September - in effect any time now through to April when the crop stage cut-off comes into play.”
“The re-registered Galera (MAPP 16413) is recommended in the same way as the existing product in the spring, but there is one important aspect to the new label that growers must be aware of. The new label states that wheat, barley, oats, maize and rape can follow an application within 4 months (or 120 days), which is straight forward, but all other crops, such as beans, need to follow after 36 months. This new restriction is not because Galera is suddenly causing new problems in these “other” crops, but more to do with tighter regulatory demands. This shouldn’t affect too many growers in a normal rotation of winter cereals, spring cereals and rape, but it is best to keep strict farm records and plan rotations. Dow AgroSciences are working with CRD in hope that this 36 month following crop restriction can be overcome, however,” he says.
