TREE CARE TIPS

Fall Webworm

It is not difficult to spot the ugly nests of the Fall Webworm this time of year. The fall webworm is a native pest of trees and shrubs. It makes its appearance in late summer to early fall, and attacks predominantly hickory, walnut, birch, cherry and crabapple trees.

Fall Webworm constructs its nest over the end of branches, consisting of a silk web over the affected leaves. The web expands to include more leaves as the enclosed leaves are consumed. Webs can eventually contain 2-3 feet of a branch. The web is similar to that of the eastern tent caterpillar we dealt with in early spring, except the latter builds its web at the crotch section of branches, while the fall webworm infests the end of branches.
The fall webworm feeds mainly on leaf tissue between the veins which results in leaves having a “skeletonized” appearance.

Fall Webworm over-winters in the pupae stage on or in the soil. Eggs are laid by female moths late in June through July. Hatching will occur during July and the young caterpillars will immediately begin building their silken web. The web protects them from predators.

Since the infestation and feeding occurs late in the season, tree leaves normally have already photosynthesized to make food during the summer and have stored the energy needed for survival and growth. However, this season, many leaves were lost early in the growing season due to late frosts and freezes. Trees had to use food reserves to push out their secondary leaves. In addition, drought has caused tremendous stress on trees. Repeated stress on the same tree can cause a mortality spiral of which a tree never fully recovers. If your trees have suffered other stressors this season, you may want to manage this pest.

• If infestation is limited to accessible branches, pruning and destroying branches that contain nests and caterpillars is effective.

• Piercing or cutting the web, will expose the webworm to larval parasites and many predators such as yellow jackets, wasps (which are carnivores), birds, predatory stink bugs and parasitic flies.

• Our arborists can spray a bio-rational (environmentally friendly) pesticide to kill caterpillars under ½ an inch. This spray will not harm the beneficial predators of the webworm or animals visiting the tree. If caterpillars are larger, we may use a different mode of management.

• Do not attempt to burn the nests of these caterpillars. Burning damages bark and the vascular system under the bark. This can seriously harm the tree.

Is Your Tree a Hazard?

Our ISA certified arborists appreciate the value and benefits of trees in the landscape. We strive to save a tree whenever it is possible. However, there are times when branches or entire trees become high risk to humans or property and the best choice is to remove the potential hazard.
Often, trees will ‘green-up’ for years, deceiving a property owner that the tree is strong and in good health. It is important to know that trees can have very little sound, structural wood and still green up.

Some of the more obvious signs that a tree may have the potential to fail are;

• Hollow or visible cavities in trees. If wildlife are using these holes, decay is usually advanced.
• Mushrooms or conks developing on large branches or more seriously, the trunk or roots. Mushrooms are the reproductive stage of fungal organisms. When mushrooms appear, decay is in an advanced stage and has been present a long time.
• Broken or partially attached branches still in the canopy. Arborists call them hangers, you may have heard them called widow makers. They are called this because they can cause fatal injury should they fall on someone.
• Carpenter ant activity. These ants are a red flag signaling present decay. These ants don’t eat wood and are not causing the tree problem.

Less obvious signs to an arborist are;

• Recent change in grade of the soil. Raising or lowering soil on a mature tree can cause serious structural problems with a tree.
• Construction activity. Vehicles driving over the root zone of a mature tree or cutting of roots can cause death of the tree.
• ‘V’ shaped or forked branch attachments. This type of trunk or branch attachment is prone to splitting.
• A leaning tree. A tree that was once straight that now has a lean, especially if the soil is raised on the outward side of the lean is a tree with high risk of falling.
• A tree with no visible trunk flare. Trees, at the base, should not look like telephone poles where they enter the ground. They should have a widening of the base to form a flare. The beginnings of structural roots should be visible above ground.
• Trees that have been ‘topped’ in the past. Our arborists won’t top trees because this method created a hazard tree. The areas where cuts ere made do not have healthy closure therefore, these trees are usually full of decay. Often these trees respond to topping by sending out rapidly growing water sprouts in an effort to attain more food with the leaves the sprouts produce. These water sprouts are weakly attached and are prone to failure.

If you have any of the above issues, our arborists should evaluate your tree. Some situations such as broken branches or branches hanging in the canopy can be corrected if the main tree is still in good health. Trees with ‘V’ attachments may be able to be cabled or braced to reduce their chance of splitting.
No tree is impossible for our experienced certified arborists to remove if necessary. We have expert climbers and specialized equipment to ensure a safe tree removal.