Key Points
- Two field trials conducted at Lincoln in May-June and Oct-Nov 2002 were set up to confirm earlier glasshouse findings which suggested that commonly used insecticides vary widely in their persistence against cereal aphids
- In the research, synthetic pyrethroids were shown to be more persistent than organophosphates and carbamates
- The insecticide Karate Zeon was shown to be the most persistent product of those tested, giving 24 days persistence at 40ml/ha and 17 days at 20 ml/ha
- Plant growth rate was not shown to be an important factor in the efficacy of the products tested
- Though temperature has some effect on persistence, ultra violet (UV) light plays a significant role in the persistence of synthetic pyrethroids
- In terms of weather conditions, whilst cold weather reduces reproductive rates, it was shown that cold wind and rain were most effective at reducing aphid numbers
- Persistence achieved under autumn field conditions, was considerably longer than when the same products were tested under glasshouse and spring conditions, i.e Karate Zeon 40 ml/ha persistence dropped to 10 days and 4.3 days respectively