Lawn damage from grubs in our area has been a hot topic. Even though grub damage has been significant, not all grub infestations warrant control. Lawns differ in susceptibility to grubs because of different grass species, soil health, irrigation, amount of sun exposure, shady areas and amount of traffic. A healthy lawn can tolerate lower amounts of grubs however, birds, skunks moles, most of the time, will damage the lawn as they feed on grubs.
Cultural practices are an important part of controlling grubs. Mowing heights of 3 or more inches, sharpening mower blades frequently and frequent watering play important roles on minimizing grub damage. A regular fertilization program with proper blends of fertilizer being applied correctly throughout the growing season is also important for a healthy lawn to withstand grub damage.
There are several grub species that cause damage to lawns in Maine. Japanese beetles and European chafers are the most common species. Adult beetles (grubs) usually lay their eggs in July and most larvae (The offspring) will appear by early August. To determine if control is necessary, you may have to sample multiple areas of your lawn depending on soil conditions etc. This can be achieved by using a flat spade to cut back a sample of turf. Cut a 12″ x 12″ area of turf and gently pull back the cut area and count the number of grubs. If you have more than 6-8 grubs, treatment is recommended.
he most effective time of year to apply treatment is during the middle of June, or the month of July (during the larvae stage) depending on weather conditions. When treating affected areas, generally, the treated area must be watered in to ensure success of the application. Treating grubs at any other time of year is usually expensive and ineffective.
Repairs to damaged area will be most successful when done in middle to late May early June depending on soil temperatures. Raking out damaged turf and replace it with clean loam before seeding. Once the damaged area has been prepared, apply starter fertilizer and grass seed to the area. We suggest rolling the area, cover with mulch hay or straw and water frequently until grass has been mowed 3 to 4 times.