Arable farmers in the region could turn away from growing bright yellow fields of oilseed rape unless an alternative way of dealing with one of the crop’s major pest problems is found, says a Suffolk-based advisor. According to Drummond Scrase of ProCam, cabbage stem flea beetle, which feeds on young oilseed rape plants leaving them decimated with “shot holes”, so-called because they resemble having been fired at with a shotgun, has become such a concern that farmers are considering not even planting the crop.

Until recently, Mr Scrase says farmers have been able to use neonicotinoid seed treatments to manage the pest, but now that these have been banned, farmers have to find alternative methods. Left unchecked, he says the pest not only reduces the crop’s vigour, potentially depleting yield, but can even eat off whole plants before they fully emerge from the soil, and the whole crop can disappear.

“Either scenario is a disaster in the current climate,” says Mr Scrase, “because low crop prices mean growing oilseed rape is already financially marginal for farmers.

“One way of helping to alleviate the problem, which we are urging farmers to consider, is to plant the crop earlier, certainly before mid-August.

“The pest goes through a variable summer dormancy period and typically comes out of that around the end of August. By planting earlier, you are aiming to get the crop in ahead of that, so it gets established earlier and tolerates the pest attack better.

“Last year, crops that were planted early into moist seedbeds managed to get away better from flea beetle damage. They didn’t escape it completely but were better able to cope.

“By contrast, those that were planted in the more traditional late August to early September period couldn’t get up and away before the damage was done.”

Although by planting earlier farmers run the risk of producing advanced crops with excessive growth, Mr Scrase says the priority is to get plants established, so at least there is a crop there at all. Excess growth can then be managed by applying plant growth regulators later in the season, he notes.

“Last autumn, an emergency clearance was granted for a limited quantity of neonicotinoid-treated oilseed rape seed, which some farmers were able to get hold of. However, for this autumn, there won’t be that luxury,” Mr Scrase adds.

Photo:  Drummond Scrase with oilseed rape (from DS) – ProCam agronomist, Drummond Scrase, says bright yellow fields of oilseed rape could be a disappearing sight unless alternative methods of dealing with cabbage stem flea beetle are found. One method to consider is planting the crop earlier, he says