Blueberries are an economically important crop for Michigan with several substantial insect pests. Industry standards put considerable pressure on blueberry growers to maintain insect free berries at the time of harvest. Because of this, insecticides are a common method for their control. Michigan also receives on average about 50 to 100 mm of rain per month during the blueberry growing season which causes a risk of insecticide wash-off and leaching into the environment. Field-based bioassays were used to determine the efficacy of insecticides to control Japanese beetles (Popillia japonica Newman) and cranberry fruitworm (Acrobasis vaccinii Riley) after receiving simulated rain fall. Soil columns were also collected in order to measure leaching of some of these insecticides. None of the insecticides used to control cranberry fruitworm decreased in efficacy after receiving rainfall. Zeta-cypermethrin and imidacloprid were the most resistant to wash off of the insecticides used to control Japanese beetle. In the leaching experiment, carbaryl was the only insecticide to leach into the lower levels of soil at a concentration high enough to cause significant toxic effects on redworms (Eisenia feoetida Savigny) which were used to determine toxicity of the insecticides at different soil depths. The results of these experiments will ultimately help blueberry growers increase the efficiency of their insecticide use and make better decisions in regards to their insecticide use and their likely to cause contamination.
Read
