Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, October 20, 1994 TAG: 9410200052
SECTION: CURRENT PAGE: 10 EDITION: NEW RIVER
SOURCE: JOE HUNNINGS
DATELINE: LENGTH: Medium
In the past, paper, white latex exterior paint, tape and even plastic bubble packing (among many other things) have been used to prevent sunscald.
The information that follows is based on a survey of attitudes of members of the International Society of Arboriculture toward trunk protective materials and their current use:
Wrapping, painting, or installing trunk protective devices around all planted trees no longer is a standard practice. If protective materials are used, their use is altered based on tree species and size being planted, planting time of year, and site and micro-climate peculiarities.
Very few members now follow the "textbook" recommendation to protect the trunks of all newly planted trees.
They cite insignificant benefits, expense, and problems they have seen develop from the use of protective materials as reasons to discontinue universal protection.
When protective materials have been used, they were generally temporary, with actual or recommended removal usually after one year.
The top six species listed by International Society of Arboriculture members to receive trunk protection were maple, linden, crab apple, oak, locust, and ash.
Protection from sunscald was the top-ranked reason to use protective materials.
The next was protection from equipment and animal damage. Other reasons included protection against frost damage and vandalism.
The most commonly used protective materials are paper wrap and commercially produced plastic guards. Also in use are "homemade" plastic guards, burlap wrap, and paint.
Damage reported from the use of protective materials include cracked or split bark, fungal and bacterial diseases due to excess moisture held behind wraps, borer infestations under plastic guards, cambial damage during the summer due to high temperature injury, and most frequently, damage due to trunk girdling or construction.
A recent report noted that where dogwood trunks had been left unwrapped, few dogwood borers were found.
Where trunks had been wrapped with a plastic guard, a greater number of borers was found, with more occurring where the wrap was tight against the trunk as opposed to loose.
This is contrary to claims that wraps (paper and burlap) repel adult borers and prevent egg laying, and that if wraps (paper) are too loose, adults will not be prevented from laying their eggs.
The original reason for recommending the protection of trunks of newly planted trees - reduction of damage by the sun - is still important.
Of greater concern, however, appears to be purely physical protection against numerous destructive forces. The majority of International Society of Arboriculture members feels that the decision to use a protective material should be an individual one that takes a variety of plant, site, and environmental factors into consideration.
Where trunk protection is needed, appropriate materials should be selected, and they should be checked frequently for refitting until they are removed.
No matter what initial benefits may be derived from these materials, and no matter what improvements may be made in available protective materials, the recommendation to remove materials after a prescribed period of time must be followed.
Because tangible injury has been seen from the use of many of these materials, the possible short-term benefits should be weighed against possible long-term damage.
Joe Hunnings is the Virginia Cooperative Extension agent for agriculture in the Montgomery County Extension Office in Christiansburg. If you have questions, call him at 382-5790.|
by CNB