Updated: Nov 24, 2020
A vigorous combination of oilseed rape and companion plants drilled near Standish in Lancashire has shown excellent establishment and development and very little grazing damage from cabbage stem flea beetle (CSFB) this autumn.
The 2ha crop of RGT Beetleblocker, a combination of RGT Blackmillion oilseed rape, fenugreek and berseem clover chosen to reduce flea beetle damage, was drilled on 9 August at 13kg/ha along with 30kg/ha of nitrogen in the seed-bed.
“It shot out of the ground,” says ProCam agronomist Kathryn Richards. “Just 12 days after drilling, most of the rape was already at 1-2 true leaves.
“It was drilled very early for this area and got away fantastically at a time when beetle grazing pressure was really quite low.”
By 4 September the crop had reached a minimum of 4 true leaves.
“On the same day flea beetle had started to damage some OSR just down the road, which had been drilled slightly later. However, there was hardly any damage on the RGT Beetleblocker."
Bigger and healthier
“There wasn’t too much damage on the hybrid rape in the rest of the field either. However all along the RGT Blackmillion plants in the RGT Beetleblocker mixture have been much bigger and healthier than those in the rest of the field.
“We have put this down to the nitrogen being released by the berseem clover as root nodules were very evident by 28 September.”
Weed pressure forced a post-emergence herbicide application at the beginning of October, which started to kill the clover.
“We would have liked to keep the clover there for longer, but due to the weather conditions after drilling we couldn’t follow with a pre/post emergence metazachlor application, so we had to take the weeds out before they got too big,” says Kathryn.
“However, the crop looks well set up and if it continues to build on its good start it should enter the winter in very good condition.”
Yorkshire trial highlights difference in grazing pressure
A significant difference in CSFB grazing has emerged between RGT Beetleblocker and straight RGT Blackmillion in a fully replicated and randomised trial at Ryton in North Yorkshire.
By 20 October, the beetle damage measured as the average number of bite points per treatment was just under 20 in the RGT Beetleblocker, well under half the 43 bite points recorded in the straight RGT Blackmillion.
There was a strong correlation between this result and the numbers of beetles caught in traps, with 11 in the RGT Beeltleblocker and 26 in the RGT Blackmillion plots.
“The results are really encouraging,” says RAGT technical sales manager Cathy Hooper.
The significant drop in trap numbers and predation in the RGT Beetleblocker plots suggests the fenugreek is deterring beetles from landing in the crop.
“The hope is that this will also feed through to a reduction in larval numbers, which will be assessed in the spring.”
No further damage or increase in numbers was observed after 20 October, Cathy adds.
RGT Beetleblocker key facts
· Consists of RGT Blackmillion, a new high gross output, vigorous hybrid oilseed rape, plus fenugreek and berseem clover
· Fenugreek is a key ingredient in curries and appears to act as a natural repellent to cabbage stem flea beetle
· Independent trials in France show the mix reduced flea beetle numbers by 25% by early October and by 70% at the end of that month when sown as a companion crop
· Berseem clover has been added to boost weed suppression, nitrogen fixing and soil conditioning
· RGT Blackmillion has impressive autumn vigour, essential to help young rape plants grow away from flea beetle pressure.
To learn more about this OSR download the latest datasheet.