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March 2008 Gardening Q&A
Pests in the yard and garden
 by B. Rosie Lerner
Purdue Extension Consumer Horticulturist
Voles, bagworms, insects and viburnum borers cause woes
Q: We plant sweet potatoes in a raised bed the length of our garden. This past year, some potatoes grew 10 inches long and 8 inches around. Then we had an animal go underground and eat one-third of them. I’ve read that an animal — “a vole” — could be the problem. What can we do about it? — Mrs. Glen Morehouse, Milford, Ind.
A: There are several species of voles (field mice). Voles are active day and night, year round. Their territory is usually one-fourth acre or less but varies with season, population density, habitat, food supply, and other factors. Voles construct many tunnels and surface runways with numerous burrow entrances.
Voles eat crops and also damage them when they build extensive runway and tunnel systems. Runways are 1 to 2 inches wide and the vegetation may be clipped close to the ground. Feces and small pieces of vegetation are found in the runways. Other animals such as ground hogs could be the culprit, but in the end, the strategies to reduce damage are about the same.
Good garden sanitation can help reduce the likelihood and severity of vole damage. Eliminate weeds, ground cover, and plant litter in and around the garden. Small garden areas could be protected by placing 1⁄4-inch metal mesh hardware cloth cylinders around the planting. Bury the mesh at least 6 inches deep to keep voles from burrowing under the cylinder. And finally, a good garden cat might help!
Q: I had a 3-year-old Colorado Spruce tree and it did well until this past summer. The needles were eaten off gradually by something I couldn’t see. I finally dug it up. I also have a pretty Blue Spruce that is nearly 2 years old. Is there anything I can spray on it to keep it healthy? — Maria Adams, New Salisbury, Ind.
A: There are several insect pest possibilities, including but not limited to bagworms, sawflies and scale insects. Since blue spruce is a selected cultivar of Colorado spruce, they would be likely to share pests in common. But unfortunately, it is not possible to identify the culprit without more info about symptoms and signs of feeding damage. Control recommendations, be it a “spray” or other method, can only be appropriately suggested after first identifying the cause.
Keep a close eye on the blue spruce so that if an insect or other problem should arise, you can bring in a sample to your local county Extension Service office for assistance in getting the culprit identified. And in the meantime, you might read up on Purdue’s publication on bagworms to see if that looks like what happened to your Colorado spruce: http://www.entm.purdue.edu/Entomology/ext/ targets/e-series/EseriesPDF/E-27.pdf.
Q: I have a 10-year-old snowball bush that was taken from a cutting of a cutting from my grandmother’s that dates back probably 80 years or more. The year before last, some of the sections growing up from the ground wilted and died. Last year, when one of the three remaining sections failed to bloom (and the other two looked like Charlie Brown’s Christmas tree), I investigated and found a white caterpillar hidden in little sawdust sacks burrowing in grooves up inside the bark around the entire base of the three sections. I cut the dead section out, and I tried to pull the little buggers from the two surviving sections. But the softened bark came off with them. What kind of bug is this, and is there anything I can do to save this bush, or is it doomed? Is there anyway to get a cutting from this plant to start a new one?
A: Sounds like one of the viburnum borers, which as an adult is a clearwing moth that emerges from the tunneling larvae in midsummer. Affected plants are, at best, weakened and, in serious cases, can dieback as you’ve experienced. Plants that are injured and/or stressed are most susceptible to attack by borers. Avoid pruning plants during the growing season and keep mowers and weed whips well away from the stems. Remove all affected stems, preferably during the dormant season; however, now is better than midsummer. Plants can be sprayed with either permethrin or bifenthrin (Ortho) in midsummer, just after the adults emerge.
As insurance, in case the plants do not recover, take cuttings anytime in late spring or early summer, selecting the healthiest-looking twigs. Take a 6-inch or so length of the stem tip, remove the lower pair of leaves and dip the cut end of the stem in rooting hormone. Insert the cuttings into moistened potting soil or vermiculite, and keep the humidity high around the cuttings with a ventilated plastic bag. Gently lift the cuttings out of the mix in 3-4 weeks to check on rooting status. Once the new roots are an inch or so long, you can either transplant them in a protected outdoor location, or repot and raise them in containers until early fall.
Written By: eceditor
Date Posted: 3/4/2008
Number of Views: 370
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