|When/what do I apply to kill grubs?|
|You have a number of choices when it comes to grub control. First there's a product called milky spore. It is a Bio-safe Organic wettable powdered form of a microbe ('Bacillus popilliae'= "milky spore", aka 'Bacillus thuringiensis' or "BT") which controls more than 40 species of white grubs (especially Japanese beetles) is sold under the names of Doom, Japidemic and Grub Attack. While this method is effective, you may not achieve optimum results for several seasons while the bacteria adapt to and begin populate the root-zone which makes life difficult for the grubs.
Another Organic control for grubworms is the use of beneficial nematodes. The nematode-powder (sold under many brandnames including Bioquest) can be ordered from biological suppliers (web-search for these). Mix with water and spray onto the affected area. It is important to water immediately after application. Best results are achieved by applying during the mid-summer months when the grub populations are at their highest.
Other controls include products called Grubex and Bayer Advanced Season-Long Grub Control granules. Apply according to label directions: Grubex in late summer and Bayer Advanced in spring or summer.
Good luck with your project!