ANOTHER good weather week and one more problem seems to have disappeared for Scottish farmers as Bayer's Pollen Beetle Predictor has shown that most crops will not have outgrown their susceptible growing period for the pest.

Forward crops have produced a sea of yellow over the last week and are now well past the damage susceptible phase. It is now just backward crops going through the green to yellow bud phase that are of concern.

In Scotland, Bayer's Neil Thompson said that the growth stage range of OSR crops in Scotland is currently from stem extension to first flowers open. The 'percent migration map' is showing from just 15% at Huntly to 23% at Haddington.

Therefore, it's looking like most crops in Scotland should get safely past the damage susceptible stage before pollen beetle build up to any significant numbers.

At Rothamsted Research, which is close to the Welwyn Garden City weather station, Dr Sam Cook reported that it had both forward and backward crops and that pollen beetle counts in their backward crops have not yet reached threshold.

“We are monitoring six such crops closely and on Monday, April 3, beetle counts ranged from four to 17 per plant. Plant populations are in the 30 to 50 per square metre range, so the treatment threshold is 18 per plant.

"They’re currently in the green to yellow bud phase so whether they’ll need to be treated or not will depend on migration this week. It looks like three out of the six will not reach threshold and three may.”

Her interpretation is that the next week should continue to bring moderate levels of migration but maybe not enough to hit treatment thresholds before backward crops begin flowering.