Photo: Installing a rain garden (in the foreground) did not solve this water runoff issue. Once Pearl’s Premium was planted, long roots (12-48") not only absorbed the runoff water, but took care of the grub problem as well!
Typically 1-4 grubs per square foot is not a problem. A healthy lawn can actually stand up to 6 grubs per square foot. But more than about 8 to 12 is an indication that your soil is too wet. Grubs need constantly wet soil to thrive. If you water your lawn every day, you’re contributing to the very problem you’re trying to solve.
One possible solution to grubs is Pearl’s Premium Ultra Low Maintenance Lawn Seed, an eco-friendly grass that uses 75% less water, needs mowing only once a month, never needs chemicals to stay green year round, and helps you keep your grub problem at bay. A long rooted grass, Pearl’s Premium’s extensive 12-48 inch roots reach deep down into the soil and through capillary action draw water from the surface, pulling it deep into the ground, holding it in the roots and in the space between the roots and soil, to be used as needed. Pearl’s Premium acts better than a rain garden to help absorb rainwater runoff from roofs, driveways, walkways and parking lots. You’re now saving on water, and keeping grubs under control without chemicals. You will never eliminate grubs completely, but because Pearl’s Premium’s root system is so substantial, a small amount of feeding by grubs is less likely to show damage.
When planting a new Pearl’s Premium lawn http://www.pearlspremium.com/getting-started/new-lawn-installation [13], once you have established the lawn (about a month) and have cut back on the water, or in some climates stopped watering, grubs will begin to move away. Over time, you will have fewer grubs due to the deep roots and drier soil that constitutes a Pearl’s Premium lawn.
If however, you have a large low standing area that tends to collect runoff water and stays wet for extended periods of time, Pearl's Premium may not be enough. In that case, you can apply Milky Spore, which works best with two applications one week apart. The spores infect the Japanese Beetle larvae (one type of grub) and once established in your Pearl’s Premium lawn, can fight off these grubs for up to 10 years.
Nematodes can also help. They are microscopic, non- segmented worms that occur naturally in soil, but be aware that there are good and bad nematodes. Since most soils are lacking in good nematodes, you might consider purchasing some of these. http://greenearthagandturf.com/beneficial-nematodes-grub-control.shtml [14] These beneficial worms attack only soil-dwelling insect larvae and beetle grubs, leaving plants alone. They are not known to be harmful to humans, animals, plants, earthworms and other organisms, but they do aggressively go after insects such as grubs. Nematodes are shipped to you in the juvenile stage, and are susceptible to UV light, so it is best to apply them in heavily overcast or rainy conditions - at dusk or during rainfall are ideal.