- Discoloration of leaves, around the edges in particular
- Total drop of leaves by midsummer
- Dying upper portions of the tree
- The onset of “suckers”—branches growing from the tree’s base
Healthy oak trees are beautiful, and properties with them are sought after for good reason. But a diseased oak tree can be a major liability, so recognizing the infection will help you advise your clients accordingly.
Dutch Elm Disease
Another fungi-related infection is Dutch Elm disease (DED). It most commonly occurs in American elm, Red elm, and Rock elm trees. As with Oak Wilt, this disease causes an infected tree to die. However, if caught early, the affected areas can be pruned, and the tree can be saved. Signs of Dutch Elm disease include:
- Out of season yellowing/browning of outer leaves, eventually spreading towards trunk
- Late spring/early summer drop of leaves
- Brown streaking underneath bark of infected branches
As noted above, some Elm trees can be treated with fungicides to prevent trees from DED-related death.
Emerald Ash Borer
Perhaps one of the most insidious pests, the Emerald Ash Borer (EAB) is an invasive insect that is hard to detect until it’s too late. If left unchecked, EABs will kill trees they infest. EABs are beetles that affect ash trees. Signs of EABs on a tree are difficult to spot, making this a tough one for any Realtor® or homeowner. Here are a few things that may indicate their presence:
- Excessive woodpeckers on a tree
- Spotting the actual beetle —which has a metallic green color—on a tree, (not always easy to do, but it’s possible)
- Thinning and yellowing leaves
- D-shaped holes in the bark
If you suspect a tree has been invaded by the Emerald Ash Borer, it’s advisable to call an arborist. They can assess the tree and provide expert analysis and recommendations.
Another common disease to trees native to Minnesota is anthracnose. This fungus can infect several species of Minnesota trees, but most commonly infects oak, ash, and maple trees. Signs of anthracnose include:
- Curling/darkening edges of leaves
- Early leaf drop
Here’s some good news: anthracnose does not result in the death of the tree. Therefore, the risk of a tree falling or causing other damage to a property is extremely low. Nonetheless, given how common anthracnose is, Realtors® and homeowners should be aware of this disease. Recommended treatment includes pruning diseased branches and raking up fallen, diseased leaves soon after dropping.
The most common disease affecting apple and crabapple trees in Minnesota is apple scab. If you’ve been to an apple orchard in the fall, you’ve likely encountered trees infected with apple scab. Signs are usually easy to spot, and include:
- Olive green spots visible on leaves
- Apples that have black lesions and/or brown spots
In most cases, fungicides can treat a tree with apple scab. Proper timing of treatment is important, so it’s helpful to consult an arborist.
Stay Informed and Connected
As with any potential problems on a property, knowledge is power. Educating yourself on common things to look for concerning diseased trees will help you advise your clients. You could also consider partnering with a local arborist to seek expert advice when needed. When it comes to homeownership in Minnesota, buying and selling property with healthy trees will help you and your clients in the long run.