Answer: Do you think they are digging for worms or for grubs? Sampling for grubs is a good first step in determining the cause of your lawn problem. Random holes throughout the lawn will give you a general idea of how large the grub population might be. You can cut a square foot of turf out, pull it up and look on the soil surface and on the roots for fat, white grubs; less than six grubs per square foot can usually be masked by water and fertilizers. Populations between 10 and 15 per square foot can cause significant turf damage in September and October. Of course, populations occasionally reach 40 to 60 grubs per square foot and these levels can cause significant damage. If you find grubs you can treat your lawn with a product like Grubex or Bayer Advanced Season-Long Grub Control granules, applied according to label directions. If you don't find grubs, you can simply rake out the bare spots, sprinkle some compost over the areas and reseed. Grass seed should germinate in 7-14 days.
A bio-safe, organic solution to grubs is milky spore, a wettable powdered form of a microbe known as 'Bacillus thuringiensis' or "BT". It is sold under the brand names 'Doom', 'Japidemic' and 'Grub attack'. Another organic control for grubworms is using beneficial nematodes. The nematode-powder (such as Bioquest) is mixed with water it is then sprayed on to the affected area. It is important to water immediately after application. Best results are still during the mid-summer months as this is when the grub populations are at their highest.
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