WHITE mustard’s potential for controlling flea beetle control in oilseed rape crops, is to be investigated in BASFsponsored trials.

When grown as a companion crop, it can help alleviate issues caused by the ban on neonicotinoid insecticide seed treatments.

Since the ban, there have been many instances of severe crop damage or even complete crop loss due to the beetles’ adult feeding and larval damage.

Small plot experiments in recent seasons suggested that white mustard grown amongst or next to OSR plants may reduce grazing damage by adult beetles, said Clare Tucker, the business development manager for BASF.

Research group, NIAB TAG, has been a pioneer in this, carrying out two years of successive trials looking at different options that might be effective – from these it was concluded that white mustard had the most potential.

It will be extending its work on the concept this season, both independently and in collaboration with BASF.

In parallel, BASF is also setting up its own grower trials to test the concept further.

Several seed rates will be assessed in both trials to help identify optimum white mustard populations that offer the best degree of protection while causing least competitive impact to the crop.

“It’s important to do detailed research on this since it’s a fine balance between being an effective deterrent to the beetle whilst not damaging yield potential as white mustard is a vigorous plant,” said Ms Tucker Both sets of trials will use Clearfield oilseed rape varieties that will enable the white mustard to be controlled effectively with Clearfield herbicides without risk of crop damage, once the OSR is established and beyond the high-risk period.

“It’s not enough for a companion crop to reduce pest pressure at the critical time. Growers also have to be able to remove it from the crop, otherwise it can compete and affect yields,” she said.

“Clearfield gives good control of white mustard, so it’s a good option.” Simon Kightley, NIAB TAG’s oilseed rape specialist, added that experiments carried out in 2015 and 2016 indicated some scope for reducing grazing damage by adult beetles.

At one site near Cambridge, this technique provided the only protection for OSR plants in 2016, when all other OSR trials and OSR mixtures in companion crop experiments were wiped out by the pest, he pointed out.

“I am really excited about this discovery,” said Mr Kightley.

“In a field of 24ha, the only surviving plants last year were within a small number of plots with the white mustard mix. I just can’t wait to get going with the new planting season to validate the concept.”

The work will be carried out at three regional sites, said Jane Kitchen, BASF’s OSR campaign manager.

Plant counts and feeding damage assessments will be taken from emergence through the following two months.

Then, larval counts will be taken in early spring, and plots will be taken to yield.

BASF’s grower trials, supported by the company’s agronomists, will test the approach on farm and gain feedback.

“All agronomic inputs on the crops will remain unchanged, and the timing of the Clearfield herbicide application is likely to be around mid-October,” she said.

“We think this technique has potential to alleviate early feeding pressure and help crops get through the critical early emergence and growing phase when plants are at their most vulnerable.

“If this approach really works, it will go a long way towards restoring grower confidence in oilseed rape, by ensuring successful establishment in areas where flea beetle is starting to be a worry, perhaps even in the worst-hit areas.”