University City

November 30, 2012

Holiday tree ‘decorations’ fight cankerworms

John Neilson, president of the Autumnwood neighborhood association, has a unique new twist on seasonal lights and yard decorations that makes a lot of sense.

John Neilson, president of the Autumnwood neighborhood association, has a unique new twist on seasonal lights and yard decorations that makes a lot of sense.

Along with more traditional holiday buntings, Neilson has encircled trees in his front yard with fuzzy white wrap, held in place by sticky green plastic bands. I’ve seen worse-looking decorations, but this isn’t an avant-guard artistic statement.

By wrapping his trees, Neilson is fighting back against one of our region’s most annoying pests, the cankerworm. The technique is highly effective and completely organic, with no pesticide involved. In fact, by banding, Neilson and his neighbors reduce the need for costly spraying in the spring.

Cankerworms, or inchworms, are the larva of a native moth. In late autumn and winter, the wingless females crawl up the trunks of trees to lay countless eggs high in the branches. In early spring, these hatch into tiny but voracious caterpillars that can strip hardwood trees bare. The caterpillars’ droppings, or frass, soon coat driveways, paths and people. Things go sci-fi when the larva drop to the ground on long strands of sticky webbing.

They may be native creatures and a fact of life here, but cankerworms are definitely not on that “World Class” list Charlotte’s boosters like to brag about.

Banding works by catching the climbing females in a sticky trap. Neilson’s approach resembles a high-tech version of flypaper. An alternative method relies on Tanglefoot, a sticky paste used by organic gardeners to trap insects.

Charlotte’s concerted campaign of banding and spraying (using the organic pest control agent Bt, applied from aircraft at precisely the right time) has apparently helped control cankerworms in such South and Central Charlotte neighborhoods as Dilworth and Myers Park. Now, some of the worst outbreaks have moved to University City and Concord.

In March, the Observer’s Steve Lyttle reported on a severe cankerworm outbreak in University City. Jack McNeary, who has been independently researching Charlotte’s cankerworm outbreaks for more than a decade, reports great concern this fall in Cabarrus County, including the area considered part of University City.

Charlotte City Arborist Don McSween supports banding this year:

“People should keep up with the banding to keep the populations lower and avoid the need for another aerial spray,” he said.

The city of Concord has organized a banding program. City staff is installing bands on trees on public land, and the city has offered free lessons to residents on how to install bands correctly at home. Since trying to control the caterpillars in the spring is extremely difficult if not impossible once the cankerworms begin causing problems, Concord officials feel fall banding is the most effective and lowest cost control, particularly when everyone in an affected area bands trees together.

In Charlotte, an annual city program allows neighborhoods to apply for a grant to cover the cost of banding. Residents can check with their neighborhood associations to find if banding materials are available at reduced cost this year.

UNC Charlotte biology professor Larry Mellichamp says that UNC Charlotte does not have funding for banding program, but he may be banding some trees in the Botanical Garden. A recognized authority on plants in our area, Mellichamp has some tested practical advice and an important warning:

“It is absolutely wrong to use tarpaper and staples (when banding trees).”

He has his own method, using low cost, over-the-counter materials:

“I use Duct Tape alone (black or gray, or colors if you want to stand out) with no batting or insulation behind unless there are deep ridges in the tree such that batting is necessary to bridge major gaps. I do not like clear plastic wrap as it lets in light which heats up the bark and causes it to “sweat” and attract fungus and insect-like organisms. I wrap the tape around the trunk three or four times to give a 6- to 8-inch band. I then put on minimal Tanglefoot, heated in a paper bowl in the microwave and spread with a cheap 3-inch mini-paint roller. Most people put it on way too thickly. A person can band and paint a 1-foot-diameter tree in about a minute.”

You don’t need to band every tree, however, Mellichamp cautions:

“The trees to band are oaks, beech, chestnut, birch, cherry, crabapple, plums, dogwood, maple, Japanese maples, shadbush, redbud, and white ash. But you do not need to band hickories, walnuts, sycamore, sweet gum, black gum, tulip poplar, elm, magnolias, or evergreens (conifers or broadleaf). That saves banding about half the trees in some yards.”

The sooner bands go up, the better, according to authorities. Since autumn leaves stick to Tanglefoot, creating a passage for the insects, some experts recommend waiting to band until most leaves have fallen from the trees. Since most females begin climbing only after the arrival of colder weather, you can still reduce problems if you get bands in place during the next two to three weeks. But, don’t wait.

In the spring, you may need to take additional measures, Mellichamp says.

“Cankerworms can drop down and devastate azaleas and rhododendrons, young dogwoods, viburnum, roses, spiraeas, and other small shrubs in early April.”

Spraying with Bt (Dipel or Thuricide are well known brands), pest control soap, or pyrethrum (all organic options), or carburyl (Sevin – a chemical pesticide) immediately after observing spring damage and continuing for a couple of weeks may help protect these plants. However, spraying large trees from the ground in the spring is expensive and largely futile and mature trees normally grow back after attacks without problems.

So, why wait? Add tree banding to your holiday preparations so we’ll all get a present next spring, when we can walk out our front doors without dodging worms, webs and frass.

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