Spring weed control has been less effective than normal this season due to tricky weather disrupting spray schedules, according to experts.

“It has been interesting to monitor the performance of Atlantis [mesosulfuron-methyl + iodosulfuron-methyl] over different stages of the growing season,” said Bayer CropScience’s Gordon Anderson-Taylor.

Applications made before Christmas consistently resulted in black-grass control of up to 100%, but following the difficult spring conditions, spring applications have sometimes resulted in a lower level of control than previously experienced, he said.

“This comes as no great surprise considering the limited number of suitable opportunities to spray, but an average of 90% black-grass control constitutes a good performance given the circumstances – a performance which still must be seen as far above what any other product could offer at these timings.”

Late spring germinating cleavers are more evident than usual and growers should inspect crops closely to identify problem areas for treatment this year or in future seasons, added Farmacy’s John Freeman.

“Atlantis has provided a lower level of cleavers control than in previous years, with some fields showing only 50% control. Unless crops are inspected carefully it’s easy to miss these late recovering cleavers, until they appear above the crop.”

Where T2 fungicides are still to be applied, he suggests waiting until stunted cleavers show active new growth and spring germinators emerge then apply Starane XL (fluroxypyr + florasulam) in mixtures with T2s. Alternatively, mix Starane XL with Atlantis in future seasons, he says.