Effective BYDV control planning

The 2014 harvest is almost complete and the new crops are either drilled or just about to go in. The end of summer has generally been dry and warm, triggering expectation that certain pests will be more problematic than others, particularly aphids.

Dr David Ellerton, Hutchinsons Technical Development Director, provides a check list of items to ensure effective BYDV control whilst minimising the impact of any treatment on the environment

BYDV & New Crop Plans

It is not practical to treat all cereal crops with BYDV insecticide sprays from the point of emergence recognises Dr Ellerton. September is an extremely busy month, focussed mostly on sowing crops and the application of pre-emergence herbicides.

“It is here that the benefit of a seed treatment (e.g. Deter) for aphid control to prevent BYDV infection is fully gained, plus the environmental impact of such a seed dressing is extremely low. However it is important to remember that recent legislation has decreed that seed treated with Deter should not be drilled between 1st January and 30th June.”


“It is not until later in the autumn that a foliar spray will need to be considered, as the effectiveness of the seed treatment starts to decline. This is the critical period, judging when to come in with a follow up pyrethroid spray and ensure continued protection, without leaving the crop in a vulnerable state.”

Foliar BYDV Treatment

To extend the protection of cereal crops until the risk of BYDV from aphid invasion is passed, there are a range of pyrethroid based insecticides, says Dr Ellerton. “They are effective in most cases but their persistence does vary and this is accentuated when doses are reduced.”

The importance of maintaining full dose rates has been particularly highlighted since the detection of grain aphids resistant to pyrethroid insecticides. Therefore if aphids are found, effort should be made to identify the species present he underlines.

“If grain aphids are identified consideration should be given to utilising an insecticide with a different mode of action. However pirimicarb (Aphox) does not have clearance for use on cereals in the autumn. One possible alternative is to add an additional adjuvant such as the orange oil-based product Wetcit to a full dose of the pyrethroid, since there is evidence that it could improve aphid control even where resistance is present.”

Dr Ellerton adds that growers should take into account that pyrethroids can have a detrimental impact on beneficial insects, so it is important that arthropod buffer zones are protected and spray drift is minimised.

“Sprayer-operators are aiming to cover an upright, thin-leaved target where the ideal spectrum is to use a fine-medium quality spray. Droplets produced in the “fine” category are prone to drift and should be minimised wherever possible. The use of angled nozzles to deliver the spray “off the vertical” allows for improved coverage to an upright cereal leaf, allowing for a medium quality spray choice.”


Reduce the BYDV Risk

Additionally, minimising the threat from BYDV vector aphids will reduce the need to make foliar treatments. Ensure you have removed any “green bridge” (e.g. stubbles with volunteers) with a glyphosate treatment, as cultivations alone will only serve to bury aphids with a food source. Aphids can survive and then return to surface and pose a threat, says Dr Ellerton.