Japanese Beetles attacked our impatience last year. The flowers were planted...

Asked May 27, 2014, 3:03 PM EDT

Japanese Beetles attacked our impatience last year. The flowers were planted in the ground around our light post and in pots. Do I need to treat the soil this year before I plant flowers again to kill any grubs or larvae that remain in the soil ? I save the soil in my pots from year to year. Would it be best to just throw it away or can I treat the potted soil as well ? Thank You

Olmsted County Minnesota

1 Response

Japanese beetle larvae feed on lawn grasses. The larvae cannot survive in the soil of pots or garden soil areas without grass. If many adults are feeding on leaves in an area, it does not indicate a grub infestation in your turf. The adults may just fly in to eat your plants. The best time to apply insecticides for Japanese beetle grubs is from mid-July until end of September. Milky spore disease (Bacillus popillae) has not been as successful in killing JB grubs in MN. http://www.extension.umn.edu/garden/insects/find/japanese-beetles/