Hello, I had a beautiful, thick lawn until this year. In early June, I started noticing dead patches, in spite of previously treating with nematodes and milky spore for grubs. I dug up a dead patch and found living grubs. I applied Bayer Advanced 24hr Grub Killer Plus. It was recommended to use a longer acting grub killer as well, and about 3 weeks later I applied Ortho Bug B Gone. Both followed with recommended watering. We also had some good rain. About 6-8 weeks later, my lawn is dead, with very few patches of green grass remaining. Was this combination lethal? Should I re-sod now (or fall) or wait for any residual chemical to dissipate? Should I have my soil tested--for ??? Thank you!
Hennepin County Minnesota
http://msue.anr.msu.edu/news/how_to_choose_and_when_to_apply_grub_control_products_for_your_lawn Missouri lawn grubs are the same as MN grubs. https://ipm.missouri.edu/MEG/2011/6/White-grubs-and-other-lawn-insects/ If your lawn is comprised of cool season grasses the hot weather will have caused it to go dormant. If it wasn’t watered at least once a week and probably more often was necessary when temps were in the 90s it may have burned off. If the grass is kept shorter than 2,5 inches and mowed on hot days it will be very susceptible to dying of thirst. Grass without irrigation is naturally dormant in August. If grass is watered lightly instead of deeply the roots are very shallow and it will not tolerate extreme heat like this summer. Grub damage, grub control and water stress are likely to have contributed to the lawn dying off. Hopefully it is only dormant and you won’t have to reseed in the spring. Cultural practices that build resilency in a lawn will help a lawn cope with a very hot summer. This probably means a taller lawn and a different seed mix.
Wait for cooler temperatures to reseed. Grass puts down roots when temps are cool.
Thank you. When can I re-seed or new sod in the Spring?
The dept. of Turf Science has made a calendar available.