The spray window for oilseed rape weed control is about to open

UK - February 11, 2011

With the early signs of spring growth of winter oilseed rape and also active growth of some difficult weeds such as cleavers, sow thistle and mayweeds, the spray window is just about to open and growers are being advised to assess individual field’s needs for an imminent application of Galera, according to Dr. David Ellerton of Hutchinsons.

Dr. Ellerton warns that as soon as the weather warms up and the first fertiliser is applied, weeds will start to romp away, competing with the crop and causing costly yield, admixture and harvesting problems.  “The spray opportunity to tackle these weeds arrives all too quickly, as does the cut off timing for the main herbicide, Galera.  It is usually a tight treatment window, but if you have problem weeds such as sow-thistle, mayweeds, cleavers and creeping thistle, action needs to be taken.  Fields need to be walked now and product moved into store so that you are ready and waiting to get Galera on as soon as conditions are optimal.”

According to David, oilseed rape crops are quite variable but many are looking good with reasonable canopies, good colour and new leaves just starting to be produced.  “Most crops seem to have come through the winter well, despite the snow.  In fact the snow appears to have insulated them from the worst of the cold temperatures. But it may have curtailed some herbicide plans from November to January, resulting in untreated crops and increased need for weed control this spring.”

“Every year there are some fields that warrant a spring herbicide treatment.  With the winter closing in so early, some scuppered autumn herbicide applications plus tighter crop rotations, weeds such as sow-thistles may be more widespread.  It’s definitely worth going out to having a look and being prepared. You only have one chance to control these weeds so it is worth making the most of the window of opportunity that you have.”

“It is important that the dose rate of Galera is kept up and that it is applied when temperatures are starting to rise and weeds are actively growing. Normally this starts around mid February. There is no crop growth stage issue at the start of application as Galera can be applied from the 4 leaf stage of the crop, but it is important to adhere to the latest stage of application, which is before flower buds are visible above the crop canopy.  It can be a bit of a balance to apply the product when conditions are optimal and within the latest stage of application, but this cut off must not be stretched.”

Stuart Jackson of Dow AgroSciences adds that the recent mild weather has encouraged thistles and mayweeds to start growing and in these instances applications of Galera can be applied. “Where the target is cleavers or range of weeds which includes cleavers, it is worth holding applications until cleavers start exhibiting active growth. Generally, the trigger point for Galera applications targeted at cleavers will be the onset of growth post-fertiliser applications, assuming adequate temperatures. Wait one week and then apply. If targeting thistles, sow-thistles or mayweeds, Galera needs less active growth to provide robust control so the spray window is wider and applications can start earlier.”

Stuart also offers some further application guidance. “Do not apply to stressed crops; in other words those suffering nutrient deficiency, frost damage, water logging or severe pigeon grazing.”

“Crops heavily grazed heavily by pigeons should be left until they have recovered and are growing away.  Ensure weed growth is active before spraying to ensure quick and complete weed kill and they won’t swamp an open crop. Conversely thick crops would be best treated earlier before canopy moves and shades the crop.”

“Applied at 0.35 l/ha, Galera will give excellent control of mayweeds, creeping thistles, sow-thistle and very good suppression of cleavers.  Groundsel is also well controlled up to the 6 leaf stage and good effects on cranes-bill have been reported,” says Stuart Jackson.

For further information, please contact Stuart Jackson, Dow AgroSciences on 07976 452466 (mobile) or via the Dow Technical Hotline on 0800 689 8899.