FOR RELEASE THE WEEK OF MAY 17, 1999:
When I mow my lawn, these 1/2- to 3/4-inch long, snouted, buff-colored moths fly up out of the grass. What are they and what–if anything–should I do about them?
They’re the adult form of the sod webworm, whose larvae feed on the crowns of turf and cause irregular brown spots on your lawn. Bob Stoltz, University of Idaho extension entomologist, recommends two possible treatments: 1) Steinernema nematodes or 2) a registered insecticide such as Dursban, Sevin or diazinon. Regardless of which you choose, wait 10-14 days after you see the adults before you apply it. That will give the eggs a chance to hatch and the caterpillars, or larvae, a chance to start crawling.
Unlike billbugs, which feed below-ground on roots, sod webworm larvae feed at or above ground level. That makes them easier to control than billbugs, Stoltz says. Apply chemicals in the evening when the caterpillars are active and don’t water them in: you want the caterpillars to walk through them.
As a rule, you’d rather have sod webworms than billbugs, Stoltz says. "Unless you have very large numbers, your lawn damage will be much less and much slower to develop." It takes several sod webworms per square foot to make a serious infestation, and a treated and watered lawn will rapidly recover.
For photos of sod webworms and their damage, click on the University of Idaho’s Southern Idaho Insect Guide web site, www.uidaho.edu/so-id/entomology.
Will composting kill weed seeds?
It can, but only if your compost pile reaches higher temperatures than most home compost. Several days at temperatures above 130 degrees Fahrenheit should disarm all but the most stubborn weed seeds, says Bob Rynk, University of Idaho extension waste management engineer. Heat resisters like field bindweed–commonly misnamed morning glory–are exceptions; they don’t even break a sweat at 150.
Unfortunately, few household compost piles are managed intensively enough to exceed 120 degrees, says Rynk. Unless grass clippings or manure are added regularly, to fuel heating, your finished compost will likely contribute viable weed seed to your garden. To avoid reintroducing weeds entirely, you’ll need to dispose of seed-laden weeds in plastic bags, set them inside covered trash containers or recycle them through a commercial-scale composting facility, if one is available locally.
Is it true that overfertilizing my roses will increase my aphid problems?
It’s true, says Ed Bechinski, University of Idaho extension integrated pest management specialist. High levels of nitrogen boost the reproductive rates of aphids. "You can go a long way toward reducing the size of an aphid infestation with proper fertilization," Bechinski says. "On the other hand, if you want to have your own colony of aphids, fertilize the living daylights out of your garden."
To avoid overfertilization, apply less soluble, slow-release forms of nitrogen in small amounts throughout the growing season.
Bechinski says gardeners should also avoid heavy fertilization of lawns adjacent to rose beds. When rose roots take up lawn fertilizers, the plants respond with an increased flush of green shoots–"which is just what the aphid wants to have."
I’ve been hearing interesting things about I Bonds. What do I need to know about them?
Inflation-adjusted Treasury Bonds, or I Bonds, are based on a straightforward idea: they’re sold at face value and grow with inflation-protected earnings for up to 30 years. Sandra Cann, assistant coordinator of extension family economics for the University of Idaho, says they’re also affordable: you can invest as little as $50 or as much as $30,000 a year.
"I Bonds are safe, because they’re U.S. Treasury securities backed by the full faith and credit of the United States government," says Cann.
Another attractive feature of I Bonds is that you can defer federal taxes on earnings for up to 30 years and they’re exempt from state and local income taxes. "You don’t need to do anything to get these benefits: they’re built right into I Bonds," Cann says.
I Bonds will usually increase in value every month, and interest is compounded semiannually. Finally, I Bonds are liquid and can be turned into cash anytime after six months.
According to Cann, these bonds "go a long way toward solving the biggest problem that all investors face: finding a way to save that guarantees inflation won’t eat away the value of their savings."