Trunk Lines Autumn '01

From the desk of Mary Ann

Welcome to the first issue of Trunk Lines, an Urban Forestry newsletter. As the Urban Forestry Program continues to evolve in this county, more timely educational information needs to be relayed to professionals and homeowners, so here we are! In each issue be sure to look for "Shigo's Corner" featuring topics from Dr. Shigo's book, Modern Arboriculture.

This past year has been busy, as we have gone through some changes. In January, we had TreeFest giving away over 16,000 tree seedlings to over 3,000 people. On March 17, with the help of residents and volunteers, 180 trees were planted in the Creekwood apartments. In April, Kent Wooten came on board as Extension Director, who is as much a gentleman as he is approachable, dedicated and hard working. Please be sure to introduce yourself and welcome Kent.

In Spring, a second advanced class on trees was offered to Master Gardeners called "Tree Masters". Graduates who work on the hotline now feel more knowledgeable on most tree related questions; others have assisted with urban forestry activities such as the Arboretum Tree Survey and Market Street Tree Evaluation.

This Fall, we have classes set up for ISA Arborists to receive Arborist Certification Credits. The dates, times and topics are in this newsletter.

This issue has been mailed to an extensive mailing list. If you would like to continue to receive this newsletter, please mail back or drop off the enclosed subscription form.

3rd Street Magnolia Tree

The magnolia located in the median at the Elizabeth Holmes bridge, 3rd Street and 17S will be removed due to the Smith Creek Parkway road improvements. The state looked at this intersection from many angles and couldn't come up with a safe solution which would leave the tree in place. This magnolia survived a previous road improvement and has for many years (some say 100 years) served to softened an otherwise harsh concrete intersection. The trees' absence will be noticed by many.

Pests To Look For . . .

The black twig borer, a type of beetle, is a known inhabitant of our local woody plants. The insect makes its home within healthy limbs by eating a hole (about 0.8 mm in diameter) into the bark. The tiny entry hole can be found on the side of a tree's terminals as well as the undersides of twigs and branches at the interface of dead and live branches. The female beetle enters the tree only a few centimeters but can create a cavity that can hold as many as 20 females and their young.

Symptoms of damage from the black twig borer may include wilted foliage and shoots, ultimately ending in dead twigs and small branches. To confirm the presence of this beetle look for a small hole in twigs at the base of the dead foliage and above the live foliage. Although the borer doesn't kill the tree, it can be responsible for limiting tree growth as well as a loss of aesthetic value. Some of its favorites include the Dogwood, Hickory, Maple, Sweetgum, Magnolia, Redbud, Redbay, Sycamore and even the Oak. Typically, trees show damage in August/September. Black twig borer populations were heavy in some neighborhoods this year. Chemicals are NOT needed to rid trees of the black twig borer. Simply trimming dead branches below the dead area and into the healthy wood will rid the tree of this insect. Proper disposal of damaged limbs will help prevent further infestation.

Research Update:

Growing Methods Affect Transplant Survivability

Have you ever wondered how the trees you plant were grown? You should. While the method of production is not readily noticed when you purchase plants, it does affect post-plant survivability. Recent research conducted by Dr. Edward Gilman at the University of Florida explains why.

Gilman tested the transplant survivability of live oak (Quercus virginiana) when nursery-grown in various types of containers and when grown in the field. To do this he grew seedlings to a height of approximately 4 feet in #3 containers. He then planted 160 of them in 4 different types of containers approximating a #15 container. He also field-planted trees on a 6 x 10 foot spacing.

After 1 year of growth, Dr. Gilman up-planted the containerized trees into #25 containers and grew them for another year. During the 2 years of production, half of the field-grown trees were root-pruned. All trees received similar irrigation and fertilization during this period.

After 2 years, Dr. Gilman dug the field-grown trees with a 28-inch spade and stored them for 10 weeks. Next, he planted 28 trees from each of the various container types and 56 of the field-grown trees (28 root-pruned; 28 not root-pruned) in a field on 10-foot centers. After planting, he irrigated half of the trees throughout the summer. However, he irrigated the other half of the trees only during the first 6 weeks.

Gilman found that irrigation following transplanting had the greatest effect on survivability. Regardless of nursery production method, none of the trees that he watered throughout the first growing season died. However, when he discontinued irrigation 6 weeks after planting, 44 percent of the trees died.

Of those that died, 31 were container-grown - a 55 percent loss of containerized trees that were only watered for 6 weeks. However, only 12 of the field-grown trees died and, remarkably, none of the root-pruned, field-grown trees died.

In the past few years, more containerized tree stock has surfaced in retail and wholesale nurseries. It is common to find Japanese maples, redbuds, dogwoods, weeping cherry and even large shade trees in containers. Containerized trees offer several advantages, including reduced weight and easy handling. However, they may not transplant as well as B&B stock.

Gilman mentions that the medium is probably the most important factor contributing to the death of the containerized trees. Therefore, similar results might be expected for other species of trees even though this study only tested one. Most containerized stock is grown in a loose, well-aerated medium that rapidly loses moisture to evaporation. Once you plant containerized stock, you need to irrigate regularly to ensure that the rooting medium does not dry out.

Shigo's Corner . . .

Dr. Alex L. Shigo - from 1959 to 1985 he was employed by the US Forest Service as chief scientist and Project Leader of a Pioneering Project on Discoloration and Decay in Forest Trees. He has dissected over 15,000 trees with a chainsaw. He has studied trees in many countries. His research yielded 270 publications and he has received many honors and awards. He believes that we must help trees by helping the people who work with trees by providing sound educational programs based on research.

Cavities and Wounds

Cavities often develop from old wounds and flush cuts [1]. The cavity is there because the protection boundaries separate sound wood from decayed wood - CODIT. Rot [2] may be advanced or only incipient; but it will still be compartmentalized [arrows]. If the cavity must be treated because the owner insists; then remove some of the decay, but do not dig into the soundwood. Do not break boundaries! Do not paint. The cavity could be left open [3], or filled with a foam. Cavity filling will not stop rot, and it will not strengthen the trunk even if rods are inserted.

When boundaries are broken, soundwood (scraping and inserting rods will break boundaries) rot will spread faster and the tree will be weakened.

NOTE: CODIT = Compartmentalization of Decay in Trees; trees build 4 "walls" to contain decay.

Ants and Termites and Wounds

Ants live in trees and eat away from the tree. Termites eat infected wood in the tree and usually live away from the tree. Ants and termites follow the CODIT patterns with their galleries. They stay within the compartments [arrows] that are first infected by microorganisms. Ants clean the compartments and thus regulate the spread of decay, (Remember, the chambers in the tree are the ants' home. They are "careful" miners. They leave pillars, boundaries, and supports behind. If it were not for these supports and compartmentalization, the ants and termites would cause the tree to fall soon after it was infested and everybody would lose! Wood dust indicates ants.

The next pesticide recertification class is scheduled for Thursday, October 25 at the New Hanover County Extension Auditorium. Registration begins at 8:00 a.m. The class is until 12:00 noon. Three hours of credit.

Approved classes for NCDA ground applicator licenses can be found at:

Just can't buy enough books to research those pest problems? Check out these websites:

Tree Decay: http://willow.ncfes.umn/edu/misc-treedk/cover.htm

General Insect & Disease: http://fhpr8.srs.fs.fed/us/index/html

Oak Pests: http://fhpr8.srs.fs.fed.us/pubs/oakpests/contents/html

Tree Master Graduates

Here's your chance to put that tree knowledge to work!

• Urban Tree Study, Wednesday, October 17^th -9:00 am - 12:00 noon. Volunteers needed - 4;



• Arboretum Tree Survey - training Tuesday, October 30^th & Wednesday, October 31^st from 10:00 a.m. - 12:00 noon. Volunteers needed - 12;



• 4-H Wildlife Club, 4 to 6 hours per month. Volunteers needed - 1.

Thanks you! Thank you! Thank you! Thank you! Thank you!

A special thanks to Darlene Schucker, Cynthia Davis and our long distance Master Gardener Larry Joh for assisting with the Market Street Tree Evaluation Study. Your assistance in gathering information helped to speed up and deliver this project evaluation in a timely manner. Thanks for your hard work!

Arborist Certification Classes for ISA Recertification Credits

Classes must have a minimum of 10 people per session, please give your ISA Certification Number when you call to make your reservation. There is no fee but space is limited. The classes can be attended by professionals and non-professionals.

Shigo Seminars

Dr. Shigo will be offering seminars in Portsmouth, New Hampshire. Call 1-800-841-2498 for a registration form:

• •October 18^th & 19^th, Tree Autopsy & Dissection Lab; cost $550; limit 25.



• •December 6^th & 7^th, Tree Chemistry and Biology; cost $195.

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Stinging Caterpillars

DESCRIPTION

Stinging caterpillars are the immature stages of several species of moths. They may possess short spines or be densely covered with long hairs. Some of the more common stinging species are described below.

The Io moth (Automeris io (Fabricius), Saturniidae;)larva is pea-green and has greenish spines tipped with black. A reddish stripe edged with white extends down the entire length of the larva's abdomen. The Io moth caterpillar is about 60 mm long when fully grown.

One of the flannel moth caterpillars (Norape ovina (Sepp)), sometimes known as the hackberry leaf slug, has a few long, plumose setae in its early instars. In later instars, the long setae are more noticeable and there is a short, heavy spine adjacent to each spiracle. This spotted caterpillar is about 24 mm long when fully grown

The puss caterpillar (Megalopyge opercularis (J.E. Smith), Megalopygidae) is roughly pear-shaped and densely covered with hair-like setae. The long setae may be pale yellow, gray, reddish-brown or light brown. This larva is about 25 mm long when fully grown.

The saddleback (Sibine stimulea (Clemens), Linacodidae) is one of the more distinctive stinging caterpillars. Its short, stout green body has a white saddle-shaped spot with a bright, purplish-brown center. Its thoracic legs are very tiny and no prolegs are present. This caterpillar grows to about 25 mm long when fully grown.

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BIOLOGY

Distribution -- The distribution of stinging caterpillars varies with species. However, most species are found throughout the U.S.

Hosts -- All stinging caterpillars are foliage-feeding insects. Trees, ornamentals, field crops, and fruits all support infestations of stinging caterpillars.

Damage -- Stinging caterpillars are covered with hair-like, fragile hollow spines filled with an urticating venom. When the spines are broken by contact, venom passes through the spines onto the skin of people who come in contact with them. Burning, pain, swelling, and/or prolonged itching may result. In some cases, local lesions may persist for several days.

Life History -- Because there are several species of stinging caterpillars, a specific life history cannot be given which would apply for all. In general, moths fly during the summer and lay eggs. Caterpillars hatch and grow as they feed for several weeks. The caterpillars then pupate and ultimately new moths emerge. These insects hibernate as eggs, prepupae, or pupae, depending on the species. In any case, the caterpillars usually occur only in summer.

Control -- These insects are usually uncommon and usually no control procedures are warranted. However, if particularly large populations develop, they can be treated with insecticides like other leaf-feeding caterpillars.

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Contact Information

Mary Ann Metcalf, C.A.
Urban Forestry Agent and Pesticide Coordinator
New Hanover County Center