Zoysia is a hardy warm season turf grass, but even it cannot always stand up to the damage white lawn grubs can cause. In cases of heavy infestation and grass death, excision of the dead turf and installation of new will be required. Light damage where the grass remains green can often be overcome in time with good cultural practices.
Lift up loose areas of your zoysia lawn damaged by grubs and water the soil below until drenched. Lay the loose but still living turf back onto the soil surface and step on it gently to press it into place and make good contact with the wet soil surface. Water over the top of the grass patch until drenched and keep the area moist until the grass roots back into the soil and begins producing green top growth again.
Strip away dead zoysia grass by cutting around the edge of the damaged area with the blade of a shovel or spade. Discard the dead turf and do not compost it, preventing the spread of the beetle larvae or grubs.
Spray the soil with a insecticide product containing as an active ingredient either imidacloprid or isofenphos. Apply according to label directions using the recommended dose and water in well. If you are making repairs in the late fall, winter or spring, skip this step as it is only effective on the grubs when they are eggs or very young grubs in the summer and early fall.
Loosen the soil with your spade to assist the roots of the zoysia plugs or sod to penetrate the soil easily. Dig small holes to accommodate the depth and width of your zoysia plugs or smooth the soil surface for a patch piece of sod.
Press the zoysia plugs into place and firm the soil around them to secure. Cut the proper size and shape of zoysia sod with your spade or shears to fill the void completely but still lay flat on the soil surface without buckling. Press the sod patch into place.
Water the zoysia plugs or sod in well until they are drenched. Keep the patched area moist at all times for several weeks until the new zoysia is rooted in the soil below.