By Glenn DiNella
I continue to see many gardeners riding the wave of the current organic trend. Sometimes organic gardeners are laid back and willing to accept some weeds and pests if it means forgoing the chemicals. But even gardeners big on the green movement don’t like to see large, brown patches in their lawns.
Countless pests, diseases, human error, and dogs heeding nature’s call could cause brown patches. If you can’t figure out yours, grab a shovel and remove a section of turf about 8x8 in and several inches deep. Place the turf in a clean plastic bag and take it to your local extension agency for analysis. Here’s a tip: Take your sample from the area where the good grass and bad grass meet, so the scientists can compare the two.
But if your digging reveals small, C-shape, grayish/cream color worms several inches below the surface, you might want to treat the lawn for grubs. A grub-infested lawn might look like it has drought damage because basically that’s what happens. Grubs eat the grass roots; the grass can’t take up water and dies.
Grubs morph into beetles, such as Japanese beetles, that feed on roses and other ornamentals. During August and September grubs are close to the surface and munch on grass roots, so this usually is when you notice the damage. This is also when they are most vulnerable to treatment.
Grub treatments work in several ways. One typically uses the chemical Triazicide. When watered, this chemical kills the grubs on contact. Some organic products use Azadirachtin, derived from the Neem tree seed. This prevents the grub from molting and eventually kills it.
Another popular organic method uses milky spore powder. Milky spore (Paenibacillus popilliae) is a soil-dwelling bacterium. It multiplies in the soil and lasts about 15 years. The spores reproduce within the grubs, turning them a milky color and killing them. The more grubs present in the soil, the better the milky spore reproduces, and the longer it lasts.
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