Common Tree Diseases in MD & VA
Trees add a great deal of variety, shade, and beauty to your home. But they aren’t completely maintenance-free. Trees can fall victim to a wide range of diseases, each of which has its own root cause and treatment. Don’t let signs of disease in your trees go unnoticed; diseased trees can become dangerous to your home and the people who live in it. Here are some common tree diseases to look out for in Maryland and Virginia:
Anthracnose
This is a common disease among deciduous trees, especially sycamore, ash, and oak. Anthracnose also affects some shrubs.
This fungi causes unsightly dark, sunken lesions on the leaves, stems, flowers, and fruits of affected trees. It is more of a cosmetic issue than a health threat, so anthracnose doesn’t usually require treatment.
However, you can better prevent anthracnose by collecting and disposing of leaves and twigs and increasing air circulation by pruning infected twigs and branches when the tree is dormant.
Apple Scab
Apple scab is a common disease affecting apple and crab apple trees, as well as mountain ash and pear trees.
This affliction is caused by a fungus that infects leaves and fruit, leaving the fruit unsuitable for eating. Leaf spots show as olive green at first, later turning brown to black. Infected fruit turns color in a similar fashion, eventually becoming brown, corky, and deformed.
The best way to prevent apple scab is to plant tree varieties that are resistant to this fungus. However, you also can prevent apple scab in existing trees by raking and disposing of leaves before winter.
Fungicides can be used to prevent apple scab on healthy trees, but they will not treat already infected trees.
Canker Diseases
There are a variety of canker diseases that affect trees, including Cytospora canker on pine, poplar, spruce, and willow trees.
When a fungal or bacterial pathogen enters the bark or sapwood of a tree through a wound, canker diseases can result. Eventually, the tree’s vascular system becomes blocked by the pathogen and nutrients cannot flow.
Depending on the location of the canker, this blockage may cause branches to die, and if the canker is wrapped around the trunk, the entire tree may die. Stressed trees – including from environmental factors, animal browsing, or mechanical injuries – are most susceptible to canker diseases.
Some ways to prevent canker diseases include growing trees that are suited to the space and conditions you have available, avoiding injury to the bark, properly maintaining your trees and protecting them during the winter, and removing any branches affected by a canker. You also should sterilize any pruning tools used on a tree with a canker in between cuts with a 10 percent bleach solution to avoid pathogen spread.
Cedar-Apple Rust
Cedar-apple rust fungus requires two hosts to complete its life cycle: Cedar and apple or crab apple. A related fungus, cedar-hawthorn rust, infects hawthorn trees.
This fungus spreads in its first year on the cedar. During the following spring, spores are carried by wind and infect the second host, usually located within several hundred feet of the original host, but sometimes up to a mile away.
Cedar-apple rust causes bright yellow-orange spots on leaves and fruit, along with swollen fruiting bodies on stunted twigs. The tree may drop leaves and fruit prematurely.
The best way to control cedar-apple rust is to plant tree varieties that are resistant to the fungus. You also can spray a fungicide in spring before symptoms develop.
Diplodia Tip Blight
Blight can affect many tree species, but it is common on stressed conifers.
New growth is stunted, turns yellow and brown, and eventually dies. Trees that are under stress are more prone to diplodia tip blight, so it’s important to keep them properly mulched and watered, especially during dry periods.
Removing and destroying infected cones and tips is important, as well as dead or dying branches, disinfecting pruning tools between cuts with rubbing alcohol or a 10 percent bleach solution. Fungicides can be helpful if applied three times in the spring: When buds first break, when new shoots are half emerged, and again when they are fully developed.
Dothistroma Needle Blight
This blight affects pine needles, turning them brown at the tips. Slowly, the whole needle turns brown and falls off.
Dothistroma needle blight can be fatal and is most common in Austrian pine and Ponderosa pine trees.
To prevent this disease, it’s important to ensure good air circulation by avoiding crowding, mulching trees, and watering them at the base to avoid wetting the foliage. A fungicide also can be applied.
Fire Blight
When you see a tree with fire blight, you’ll see tree branches that appear to have been scorched by a fire and wilting leaves that turn black. Fire blight infects twigs sporadically, so you may see dead foliage on different areas of the plant.
It is most active in warm, moist weather and most commonly impacts fruit trees.
To control fire blight, remove and destroy infected branches, making sure to cut all the way back to uninfected wood. Disinfect pruning tools between cuts in a 10 percent bleach solution.
Oak Wilt
Oak wilt is one of the most common fungal tree diseases specific to oak trees. In species in the red oak group (pointy leaf lobes), oak wilt is fatal; trees in the white oak family (rounded leaf lobes) are less susceptible.
Beginning at the top of the tree, leaves wilt rapidly and turn brown. This fungus is passed from tree to tree through the root system or by sap-sucking beetles attracted to freshly cut wood.
Avoid pruning trees during the growing season. If you must prune an oak tree during this time, use a tree wound sealant to make the wound less attractive to beetles.
Powdery Mildew
This fungal infection is easy to spot due to the powdery white coating covering a tree’s foliage. Eventually, leaves become distorted, turn yellow, and drop prematurely.
Powdery mildew is most often found on plants in shady areas, particularly when there’s a lot of humidity but no rain.
To control powdery mildew, avoid planting varieties that are more susceptible to infection, such as crape myrtle and lilac. Give existing plants good air circulation and treat with fungicide if necessary.
Phytophthora Root Rot
Phytophthora root rot is a fungal disease that attacks trees growing in poorly drained areas.
Affected trees look as if they’re drought-stressed, with wilting leaves turning pale green or yellow.
While there are no treatments for root rot, you can prevent it. Avoid planting trees in wet areas or near downspouts, or plant water-loving species instead such as bald cypress, willow, sycamore, and black gum. Also, never plant trees deeper than they grew at the nursery – stick to planting them at the same level or slightly higher – and avoid piling soil against the trunk.
Help for Diseased Trees in MD & VA
At East Coast Lawn, we make it our mission to help your lawn look great all year long. If you struggle with any of these common tree diseases, we can help you find the best solution to get you the healthy, beautiful trees you want. Call today for a quote!