Counties split over OSR beetle damage

Cabbage Stem Flea Beetle larvae have been a particular problem in parts of the country this season

Cabbage Stem Flea Beetle larvae have been a particular problem in parts of the country this season Picture: BASF - Credit: Archant

Norfolk and Suffolk farmers have experienced contrasting fortunes with oilseed rape crop pests this season, according to experts.

Cabbage Stem Flea Beetle Picture: BASF

Cabbage Stem Flea Beetle Picture: BASF - Credit: Archant

Agronomy managers at chemicals giant BASF say certain parts of the country have suffered serious problems with cabbage stem flea beetles (CSFB), but Norfolk growers have fared better than most. Meanwhile, Suffolk farmers have had more mixed results.

Crops in the south have been particularly badly hit by pest damage, said Andrew Clune.

“A small percentage of crops were lost to adult damage in the autumn but the bigger threat that we have at the moment is the huge amounts of larvae, into double figures per plant,” he said.

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“The larvae are moving into the stems now and where the stem is elongating you can find them in the top third of the plant. It’s not pretty. There have been a few people who have tried topping and grazing the crop, to see what level of control they might be able to get in order to have some knowledge for future years.”

But Hugo Pryce said oilseed rape crops in and around Norfolk are at a range of differing growth stages largely determined by drilling date and variety, with the most forward crops approaching yellow bud, and no major concerns at the moment.

In contrast, in Suffolk, Matthew Keane said crop progress was mixed.

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“Some crops look good – they are growing nicely. They’ve taken the early nitrogen and Caryx (metconazole and mepiquat chloride) is being applied if the green area index (GAI) was above 0.8 just prior to stem extension,” he said.

“Nearly all crops were above this threshold and, even those that have been damaged by CSFB larvae are starting to grow away well. It is still worth putting Caryx on these plants to help the branching and rooting. Caryx can be applied from the start of stem extension through to yellow bud. If you have CSFB damage, then all you can do is help the plant to get to harvest.”

Meanwhile, septoria, a fungus, has taken hold across the country.

In East Anglia, Matthew Keane said septoria was there on the lower leaves. “The amount varies between varieties. The weather is the unknown variable,” he said. A lot depended on the weather. If it was wet during the early growth stages, then there’s enough septoria for it to spread up through the plant, he said.