Twig Blight: What Tree Owners Should Know About This Fungal Disease

Twig blight, also sometimes known as anthracnose or leaf blight, is a fungal condition that can affect most any species of trees, along with shrubs and some vegetables. Though typically twig blight is not life threatening, it does weaken the tree and leave it more susceptible to other more serious diseases. Thus, as a tree owner, it is important that you know how to detect, treat and prevent it.

Detecting Twig Blight

The primary symptom of twig blight is the appearance of small, dark, sunken spots on the twigs and leaves of the tree. These spots may start off tan and darken to black or dark brown over a period of days or weeks. When the infection becomes severe, some leaves may fall from the tree prematurely. In some trees, lesions begin forming on larger branches. If the lesions are large enough to girdle the branch (reach around its entire circumference), they may cause that branch to wither and die.

Treating Twig Blight

If you notice signs of twig blight, it’s important to take action to kill the fungus and keep it from spreading to other trees. The easiest way to treat it is to wait until the current growing season is over, and then carefully rake up and burning of all fallen leaves and twigs. The fungus spends the winter in the fallen leaves before “re-infecting” the tree the next spring. If the fungus-strewn leaves are gone, there will be no spores to populate the tree the next spring, and the infection should mostly be gone. (There may be a few straggling spores that make it and re-infect the tree lightly, so repeat the raking and disposal the following fall to be sure.)

Should the raking and burning method fail, it probably means you have other infected trees in the area, and the spores from the fungus that they harbor are making their way onto your tree. In this case, treating your tree with insecticides in the spring is your best bet.

Preventing Twig Blight

Do not bring leaves of other trees onto your property, as they may be harboring fungal spores that could infect your trees. Also, be sure to keep your trees healthy by having them pruned on a regular basis by a tree service and by providing water during periods of drought. The healthier your tree is overall, the better it will be at fighting off the fungus before true disease sets in.

Author: Emma Days

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