Reports of cabbage stem flea beetle infestations in harvested crops this summer only heighten the potential risk from the pest to this summer’s establishment of an increased area of oilseed rape.

Finding plenty of flea beetles at harvest can be an early warning sign of local pressure for the following crop, although plenty of other factors including distance from old crop to new crop, migration timing, drilling date and post-harvest stubble management will all play an important role in assessing risk, explains Chris Martin, Agrovista’s head of soils. 

Recent experience has shown that various tactics can add up to increasing the chance of establishment, including the use of organic amendments.

That’s one of the reasons Agrovista has been trialling the use of SeaBoost – a formulated combination of fish hydrolysate, Sea2Soil, and L-CBF TerraFed, a liquid carbon fertiliser based on molasses.

“This is a brand-new concept we’re developing,” Chris says.

Sea2Soil in Niab trials showed a 90% reduction in damage to oilseed rape leaves from cabbage stem flea beetle 12 days after application, while also reducing flea beetle damage to stems by 59% 22 days after application.

Anecdotal evidence suggests that flea beetles cannot digest the sugars in the molasses in L-CBF Terrafed, which is an equivalent product to L-CBF Boost without the addition of urea and other nutrients.

“It doesn’t kill or stop them, but it seems to make them feel bloated and unhappy,” Chris says.

Where Agrovista agronomists tested the concept last season commercially by tank mixing L-CBF Boost and Sea2Soil together, reports from the fields have been encouraging, Chris says.

“They’ve reported visible greening of the crop, even under low flea beetle pressure,” he says.

Further trials to find the best timing to apply SeaBoost to test its deterrent activity in a more controlled manner are planned for this autumn. Agrovista will also investigate mixing with its cellulose nanofibre product, Nanomesh, which acts as a physical barrier against the pest to find out whether that approach provides further protection.

Chris is excited about SeaBoost’s potential. “It’s like the ultimate biostimulant – ticking every box of what a grower would want from one. I really think we will find that every acre of oilseed rape could benefit from using it,” he concludes.