H. bacteriophora nematode application
When is the best time to apply Heterorhabditis bacteriophora nematodes to target Japanese beetles?
Montgomery County Maryland
You can apply this type of grub control when you see active grubs in your soil and their numbers exceed a threshold. Grubs do not typically affect turf-type tall fescue lawns. Grasses most susceptible to grub damage are bluegrass and creeping red fescue. Research shows that damage will occur when grub populations exceed 6-10 grubs per square foot on bluegrass, rye and fine fescue lawns and 8-15 grubs per square foot on tall-fescue lawns. Most lawns can suffer 10-15% stand reduction without a substantial loss in quality.
When you purchase nematodes for grub control, they have very specific instructions for application. In general they need to be applied in the evening (to avoid UV light), when the soil temperature is above a certain level (42F), water every 3-4 days if there is no rain, and use the product within two weeks, etc. Consultant and follow the product label instructions. Companies that supply these biocontrol products also typically have a number you can call if you have more specific questions.