Questions on: Insect Control

Ron Smith, Horticulturist, NDSU Extension Service

Q: Any suggestions on how to get rid of grubs on my lawn? We can’t afford to have a professional come out and spray. (E-mail reference)

A: I don't know where you live, but if you live east of the Mississippi, you can get a natural control known as Bt which will make the grubs sick and die as it keeps them from getting to their reproductive stage. It takes a while to work, but it is effective at controlling the grub stage of the Japanese beetles. You can reduce the population but you'll never be rid of them. There are lots of natural predators that will help to control them as well, so I advise against using chemicals especially in the hands of non-professionals.

Q: Over the past two or three years my lawn has become quite bumpy. Since the problem covers the entire lawn, it doesn’t appear to be rodent related. Do you think it could be caused by earthworms? (Mandan, N.D.)

A: Yes, and you should consider this something of a compliment! The worms have found your lawn so perfect that they have multiplied. There are some steps you can take: Roll the lawn this spring prior to mowing with a ballast roller. Run a power rake over the lawn after it greens up. Apply Sevin soil insecticide granules as if you are treating grubs. I would suggest starting with rolling to see if it works, then try the other steps if it doesn’t.

Q: My husband and I started a new lawn last August and are wondering what the first step would be for it this spring, because we have several problems. First, last summer we had black dirt and we had millions of these little brown bugs. They reminded me of sunflower mites. Some people called them soil bugs. In the fall they would get into my home if I opened the windows in the evening. I'm talking hundreds of them in my home, and they were very bothersome. They could get right through the screens in the windows. We planted trees, and whenever I would water them, those little brown bugs would surface on the rocks around the trees and there were just thousands of them. Do you know what these might be and are they harmful? Second, when we started moving dirt around to get the ground level for seeding, we saw a couple of grubs. I'm pretty sure that’s what they were, because they were white, fluffy worms and we were told they are a problem around our neighborhood. Therefore, we feel we should treat them early enough this spring before they start chewing off our newly planted grass. Third, because it is a newly planted grass, it is sparse in some areas and also very weedy, so we feel we will need to spray for weeds soon. We know that people fertilize their grass very early in the spring, too. So, as you can see I have many concerns and questions as to where to begin, and I feel very overwhelmed by it all. Based on these circumstances could you please tell me what you think is the best thing to do first, and the steps I need to take this spring to have a nice-looking lawn this summer. We do have a sprinkler system and we planted a Kentucky bluegrass mix from a seed house in Bismarck. (E-mail reference, Napoleon, N.D.)

A: Those troublesome gnats will probably be gone this spring. First things first. Yes, there will be plenty of weeds, but not nearly as bad if you had tried to plant the grass in the spring. Activate your irrigation system in May, not April. Water only if the grass needs it. When you mow the lawn for the third time this spring (at 3 inches, by the way) then you can apply a broad-leaf herbicide to control your weeds. A week on either side of Memorial Day weekend, apply some fertilizer, the lawn type, such as 28-3-6 or something similar. Right around the same weekend would be a good time to apply some grub control. Several products on the market can be watered in with your irrigation system. Grubs are a reality in everybody's lawn, so don't worry about them, as there are natural predators that often keep them in check. Manage your irrigation system so that you are applying about 1 inch of water per week either through rainfall or irrigation cycling. This should be enough to keep the lawn green and healthy. Since you have an irrigation system, make another application of fertilizer--lightly this time, about 0.75 pounds of actual nitrogen per1000 square feet. Around Labor Day weekend, again apply herbicide as needed in troublesome spots and over-seed as needed. Another application of fertilizer at this time would also be good, at the same rate as your first one. If those pesky bugs return this spring, catch some, preserve them in denatured alcohol, and send them to me for ID. We can then figure out what to do with them.

Q: Please advise me as to what I can do to level my lawn that has become very bumpy and uneven, possibly due to nightcrawlers. (Jamestown, N.D.)

A: Several things: roll with a ballast roller, topdress with topsoil, power rake—you may try any or all.

Q: My lawn is really uneven with hard bumps all over. I have been told that it is caused by earthworms. Is this true? If so, how do I fix the problem? (Ellendale, N.D.)

A: I suggest that you hire someone to come in and power-rake those pilings down to give you a more even surface to walk upon. Then apply Sevin at the label rate for grub control and water the insecticide in well. That will take out about a third of the population. Repeat again if the level of control isn’t satisfactory.

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