Keeping your trees healthy
By Taylor Kaser
Diseases from Asia aren’t just a threat to humans, native trees are fighting a battle of their own too. Bugs, fungi, and spores all threaten to decimate the local flora.
While people have antibiotics and modern medicine to aid them, trees are basically on their own, with little defenses. The help that people do try to give, through using herbicides and pesticides, can sometimes do as much harm as good.
The Ohio Department of Natural Resources advises prevention to be the best defense against flora ailments. Plant trees that are compatible with your intended location. Exotic trees native to the southern hemisphere will obviously face greater challenges in Ohio. Also, look for trees that are resistant to bugs and fungi that are an issue in your area.
Trees that are physically vulnerable are also a prime target. Trees may come under “stress” when they are unable to collect needed nutrients or water. Location of the tree can also have a bearing on its health. Maintain your trees by regularly watering, mulching, and pruning.
More natural methods of maintaining good tree health include the avoidance of high nitrogen fertilizer and chemical pesticides. These often kill beneficial insects, microbes, and nematodes. Other organic suggestions can easily be found online.
The best aid you can extend to your tree is to keep an “eye on it”. Look for clues of illness or infestations. Additional information can be found at your local OSU Extension office or at ohioline.osu.edu.
The ODNR also gives a list of common tree diseases with descriptions of what to look out for:
Powdery mildew: Usually found on crabapples, dogwoods, English oak, and catalpas. Leaves appear to have been “sprinkled with powder.” Normally the older leaves are affected first.
Leaf spots: Fungal leaf spots can be found on trees all over the state. Damage caused by theses fungi is minimal, fungicides are rarely needed. Two types of fungal spots are most prevalent: tar spots and frogeye spots.
Tar spots, found on maples, Amur, Japanese red and silver, begin in spring as yellow green circles. By mid summer the circles turn dark.
Frogeye spots attack crabapples generally, spot begin with a tannish hue with purple to red borders and then expand and turn grey.
The suggested method of halting leaf spot spread is to rake up fallen leaves and remove them from the vicinity. The spots move from fruiting bodies on fallen leaves.
Chewing insects: Trees can usually recover from the chewing assaults of spring and fall cankerworms, tent caterpillers, gypsy moths, leafminers, and Japanese beetles. Recurring infestations could eventually kill the tree.
Boring insects: These insects carve tunnels inside of trees where they lay eggs, which sometimes after hatching will burrow even deeper into the tree’s water-conducting tissue. When this occurs upper parts of the tree may be starved of essential nutrients.
Small enter/exit holes can be seen in the tree bark accompanied by small bits of sawdust at the base or branch bases. Bugs that burrow are the Asian longhorn beetle, bronze birch borer, dogwood borer, two-lined chestnut borer, ash borer, and elm bark beetle.
Sucking insects: Scales, aphids, leafhoopers, spider mites, and thrips suck liquids from branches and twigs. These insects can be seen on the outside of the trees, usually in dark scaly formations. They often excrete a sticky liquids that later turns black and is covered by fungi.
Taylor Kaser is a reporter for the Morrow County Sentinel, 46 S. Main St., Mt. Gilead. She can be reached at (419) 946‑3010.