Key Points
- A foliar aphicide persistence trial was set up in winter wheat sown in April 2017 at Plant & Food Research, Lincoln.
- The trial tested aphicides from four modes of action: synthetic pyrethroids (Karate Zeon® and Mavrik®), carbamates (Pirimor®), sulfoxamines (TransformTM) and chloronicotinyl (the seed treatment Poncho®). It also tested Eco-oil®.
- Poncho®-treated seed had residual activity to GS21 (32 days after sowing).
- TransformTM at a full rate gave 8 to 14 days persistence, similar to previous trials.
- Pirimor® gave 5 days persistence, similar to previous trials.
- The synthetic pyrethroids have not given consistent residual activity. In previous spring trials their residual
- activity ranged between 5 and 7 days. In previous winter trials when the aphids weren’t confined to the plant with clip cages residual activity had been long e.g. 25 days for the full rate of Karate Zeon®. The repellancy effect of synthetic pyrethroids may have contributed to this long activity. In this trial, when the aphids were confined to the plant, the observed residual activity has been reduced to a half or less than half the length of time compared to previous trials.
- In addition to persistence, other factors need to be considered such as price, rotating modes of action to avoid resistance developing and choosing insecticides more compatible with beneficial insects (e.g. Pirimor® and TransformTM).