Pollen beetles are already apparent in significant numbers in many oilseed rape crops and could cause similar pod set problems to last season if growers are not very careful indeed, warns national specialist, Mahon Brennan of OSR market leaders, Monsanto.

"We're already seeing multiple beetle infestations per plant in our trial site monitoring across the Eastern Counties," he reported. "If conditions remain as mild as they have been over the past week, levels are set to increase very dramatically. Which means many crops could well be in for the same scale of challenge faced last year."

Bearing in mind that pod set problems only became apparent too late to avoid last season, Mahon Brennan advises growers to keep a very close eye on their crops this time around and take timely control action to ensure pod set is not again seriously compromised.

"Many growers didn't spot the danger signs early enough last year, suffered the pod set consequences in May and had to rely on late season compensation to get them out of trouble, " he recalled.

"With many forward crops at the crucial green bud stage and some early types moving rapidly into early yellow bud and flowering, now is the time to start checking beetle populations carefully.

"If pollen beetle numbers build-up, late flowering varieties will repay particular attention," he insisted. "As we saw last year, significant populations of beetle accumulating on early/mid flowering types can really wreak havoc when they transfer across into late-flowering crops. And, of course, the later types have far less time to compensate for any damage sustained before harvest."

Masstock agronomist, Andrew Richards, who has seen significant early season pollen beetle populations in more westerly regions, is particularly worried about variable and more backward crops.

"As we saw last season, crops that didn't get away early enough in the autumn or were badly grazed by pigeons were the most vulnerable to attack and the least well-able to compensate for it," he pointed out. "We need to be particularly vigilant with these crops to avoid losses this year. Some may even need spraying twice.

"Wherever populations build-up I'm advising a pyrethroid like Contest is included with the triazole fungicide growth regulation spray and/or any trace element mixture. Crops must be sprayed before the yellow bud stage at which they become attractive to pollinating insects, though, since pyrethroid/triazole mixes can be toxic to bees. If later sprays are required, then growers should go in with Contest alone."