Trees are an important feature in your yard. They draw the eye, clean the air, provide shade, and can live for a very long time. However, your hardy plants are still susceptible to a variety of diseases that fluctuate in intensity from year to year.
Probably the most notorious tree disease we know of, Dutch Elm Disease is caused by the Elm Bark Beetle which is native to Europe. Over the last century, this beetle has completely decimated the elm population in many American cities. The disease these insects carry causes the elm trees to trigger a self-defense mechanism which blocks the transport of water up the tree. Deprived of water and nutrients, the tree begins to die from the crown downward. Depending on when the symptoms started, the tree may live 1 or 2 seasons.
Armillaria Root Rot is a fungal disease that thrives on old rotting logs in the forest but the spores can infect living trees too. An infected tree may go on to live for several years with the infection but will get progressively weaker. Symptoms include: stunted height, sparse or yellowing leaves, mushrooms or fungus growing around the base of the tree.
Affecting cherry and plum trees, Black Knot is a hard, black growth that occurs on the branches. As this slow-growing fungus spreads around the branch, it cuts off circulation and strangles it. During rainy days the knot opens up and releases its spores to infect other trees. Black Knot can be treated by pruning infected branches and with fungicide applications.
After overwintering on infected leaves that remain on oak trees, the Bur Oak Blight spreads to other leaves in the spring. You may not notice the symptoms until late summer which include black veins and wedge-shaped lesions on the foliage of the tree. The disease spreads over several years and leaves the tree weak and vulnerable to pests and other diseases.
Spruce decline is a name for a variety of diseases that affect blue spruce trees. These diseases have been spreading rapidly throughout the country in recent years, decimating the blue spruce population. The disease begins by attacking the inner needles of the branches which slowly die and drop off resulting in bald branches. As the years progress, the disease consumes more and more of the tree and can spread to other neighboring spruces.
The fungus appears as lines of small black dots along the surface of the needles. These black dots release the spores that infect other trees. Prune infected branches and clean up fallen needles. Destroying the infected needles and branches is the best way to eliminate the disease.
Symptoms of apple scab appear in spring as brown or green spots on the leaves of apple and crabapple trees. The spores are spread via dripping water or carried by the wind to infect other trees. Trees that are severely infected start to lose leaves by mid-summer, leaving the tree vulnerable to pests and diseases. To prevent the spread of disease it’s wise to incorporate disease-resistant varieties of apple trees.
At TruGreen we understand how important trees are to you and your family. With our 7-step tree and shrub care program we can keep your trees healthy, lush, and protected from pests and disease year-round.