Xtremehorticulture

Xtremehorticulture of the Desert

Grubs in a Lawn or Not?

Leave a Comment / controlling grubs, Grub control in lawns, turfgrass insects /

Q. We have had our lawn nearly 20 years without any problems until this year. It is developing brown spots in the lawn that we think might be grubs. We applied a grub killer we bought from a local nursery and the brown patches are continuing to grow. But now we think maybe the problem is not due to grubs. A. After nearly 20 years I would think that your lawn is a mixture of several types of grasses. Unless you are extremely diligent in taking care of your lawn, I would guess that you have a mixture of grasses including older tall fescue and common Bermudagrass. 90% of the problems on lawns in the hot desert are related to irrigation. The next most common reason for brown spots to occur in lawns is from disease. Insects like white grubs is not all that common here on tall fescue and bermudagrass. But it can happen. Make sure this is not an irrigation problem Turn on your irrigation system and watch the sprinklers. They should pop up out of the ground perfectly straight and not tilted in any direction. The water should spray evenly from the nozzle in all directions. After you run a normal irrigation cycle, use a long screwdriver to judge whether the soil is wet in the brown areas. Brown spots caused by grubs Information you will find on the Internet about damage caused by grubs comes from cooler parts of the country where Kentucky bluegrass is the common lawn. We seldom grow that here. Our grasses are primarily tall fescue and Bermudagrass. When tall fescue gets damaged by grubs, it doesn’t lift up like a carpet.  That information is wrong for us. If grubs are causing damage to a tall fescue lawn in our hot, desert climate, individual grass plants will pull up easily at the edge of the damaged area. Pull on green grass In several places right on the edge between the damaged area and a healthy lawn. If green grass pulls up easily from these spots then your lawn has a good chance of having grubs. Any of the grub control chemicals should stop it if you follow the directions exactly. Scott’s Grub-ex granular is a good product as well is the Bayer product you mention. If you go in this direction, use just one of them. Disease If irrigation and grubs are not the problem, then it is likely a disease problem by default. Disease problems run their course and then they are over when the weather changes. If this problem repeats every year, consider applying a fungicide as soon as you see a problem beginning to develop. Fungicides are preventive. Aeration You should consider aerating the lawn if it hasn’t been done for a while. This helps to open up the soil for better water movement to the roots. It can help to prevent disease problems. You can aerate the lawn anytime but the best time is in the spring months before it starts to get hot. Dethatching or Vertical Mowing Consider removing dead grass from the lawn if the lawn feels “spongy” when you walk across it. Removing this dead grass requires a power rake and should be done in mid fall or very early spring to give the lawn a chance to recover and grow a little bit before winter or hot weather. Importing Disease Problems Some lawn diseases can be carried into your lawn from other lawns. Improve the general health of your lawn by using a good quality lawn fertilizer or applying a thin layer of compost to the lawn during the spring or fall.

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Turfgrass Dead Spots. Insects?

Leave a Comment / lawn insect damage, sod, turfgrass insects, white grubs /

Brown spots or dead areas in lawns can be common during the summer months. It might be a disease, but then again, it could be something else. Could it be insects? The three primary reasons that lawns develop brown spots or dead areas are due to irrigation problems, the development of diseases and insect damage.  Insect damage. Probably the least likely of the three, and the most easy to detect, is insect damage. Most of the lawns in the Las Vegas Valley are turf-type tall fescues. Tall fescue is not a sod forming grass like Kentucky bluegrass. Instead, each seed produces a single plant. These individual plants are not linked together like they are with Kentucky bluegrass. Kentucky bluegrass sends out rhizomes, or underground stems, that pop up a distance away from the mother plant. When these rhizomes grow together, they form carpet-like sod that holds together. Because tall fescue produces only one plant for each seed that was planted, individual plants are not linked together. White grubs feeding on lawn roots of sod             This is important when diagnosing damage to a lawn. Insects that feed on the roots of lawn grasses, like white grubs, will cause areas of dead or brown grass. Because the mother insect lays a lot of eggs in one area, insect damage is usually localized in one or two areas. The eggs hatch, the young grubs begin to feed on grass roots and the lawn develops brown patches that correspond to where the grubs are feasting. The roots are severed by the grubs and the grass cannot get enough water so it dies in patches during warm or hot weather. One type of an adult of the white grub             Insect damage by grubs is usually in spots that are fairly well defined. Because the roots are severed, the grass can be lifted from the soil quite easily. Because tall fescue are separate, individual plants the root-severed, brown grass lifts easily from the soil. In the case of tall fescue, the grasses lift from the soil in the independently and separately from each other. In the case of a sod-forming grass like Kentucky bluegrass, they do not. Because they are linked together, the damage area lifts like a carpet.             When inspecting a lawn to determine if the damage is from insects or not, go to the edge of the damaged area, not the center of the dead spot, and pull on the grass plants lightly with a closed hand. If grubs causes the damage and it is tall fescue, many of the plants will lift easily in your hands; dead ones and green ones at the same time that were recently severed.

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