One major agrochemical group is encouraging oilseed rape growers to apply pesticides to flowering crops with drop-leg sprayers to help save costs and bees.

Bayer CropScience is working with sprayer manufacturers to develop this technique to control insects and diseases in the spring without damaging the growing crop.

The group’s head of application technology Reinhard Friessleben is focusing his attention on oilseed rape to improve the control of sclerotinia disease and flea beetles in flowering crops.

See also: Read more news and advice for oilseed rape growers

Drop-leg sprayers are widely used in vegetable crops, but Dr Friessleben sees advantages in using the system to improve safety and the effectiveness of pesticides.

“We like to avoid any plant protection products getting on the flowers, and we have had very good result in keeping them away from bees.”
Reinhard Friessleben, Bayer CropScience

The extended flexible drop-legs fitted to a conventional sprayer deliver pesticide underneath the crop canopy and so give much better crop coverage and better efficacy, he says.

“We like to avoid any plant protection products getting on the flowers, and we have had very good result in keeping them away from bees,” Dr Friessleben tells the Farmers Weekly.

His work has shown little physical damage to the growing crop from the drop-leg extensions passing through it, while the increased efficacy could lead to lower pesticide dose rates.

He is working with sprayer makers to encourage the uptake of this technique on farms following his trial work undertaken at Bayer’s Hofchen experimental station, some 15 miles south east of Dusseldorf in Germany.

“We are working with manufacturers to fine tune the sprayer and make the technique more available to growers in the future,” he adds.

The drop-legs are easily fitted and when operated have given good control of sclerotinia and pollen beetle with much less spray drift when compared with conventional spraying.

Effective control of sclerotinia relies on good spray penetration into the crop canopy, and the best spray timing is usually prior to mid-flowering, while for pollen beetle the critical stage for spray treatment is earlier at the green to yellow bud stage.

As well as oilseed rape, he sees the technique being used in other broad-acre crop such as corn (maize), cotton and soya beans.