Plant Health Care – How to Identify Diseases in Your Trees and Shrubs
How do you keep your plants healthy? You’re diligent about watering them, feeding them, pruning them, mulching them, etc. But what if a disease hits one of them? Not only could it significantly harm the plant itself, it could then spread to your other plants as well. How do you recognize these diseases in your trees and shrubs, and what do you do about them? Here are a few symptoms to look for.
- Blotchy, Brown Areas – If you notice blotchy, brown spots on your tree’s leaves—particularly if they’re also curling up—it may be a sign of anthracnose. There may also be orange and brown spots on green twigs. Anthracnose is most common during cool, spring weather, and is most likely to affect trees such as ash, elm, maple, oak, and birch. As long as the disease is only on the leaves, simply trim them and apply fungicide, and you should be OK. However, if it spreads to the twigs, it’s likely to kill the entire tree. If this happens, you may need to remove the tree, and then treat any surrounding trees with fungicide to keep the disease from spreading.
- White Powder on Leaves – This indicates a powdery mildew fungus on your shrubs. It’s particularly prevalent in areas of high humidity, and can kill your plants over time. Prune away all leaves that have the white powder. Water the plant right at the root, to prevent too much moisture from accumulating on the leaves. Then apply a fungicide. You may need to apply again a week or two later.
- Black Fungus on Leaves, Fruit, and Branches – This is a sign that your tree has sooty mold. It comes from aphids that secrete honeydew on the tree. The honeydew provides the perfect conditions for sooty mold growth. This is an irritating problem, but generally doesn’t harm your tree much. However, it may damage the grass and anything else growing on the ground under the tree. It may also stunt the tree’s growth, as the black mold on the leaves blocks out sunlight. The best way to get rid of the mold is to get rid of the aphids. You can do this with neem oil, or a solution of water and dish soap.
- Wilting, Browning Oak Trees – If your oak trees are wilting and the leaves are drooping in the spring or early summer, when they’re supposed to be perky, you may have oak wilt—a fungus spread by sap beetles. You may need a fungicide injection, directly into the roots. Oak wilt also spreads quickly, so any surrounding trees will likely need to be treated as well. Call your local tree doctor for help and advice on this one.
- Blackened Twigs and Branches – If your tree or shrub looks like it’s been burnt, it may have fire blight—a nasty and virulent bacteria. If this happens while the plants are dormant, then simply trim the infected area away. If it happens while the plants are in season, though, then pruning can actually facilitate the spread of the disease to the surrounding plants. The offending shrub may have to be removed instead.
By understanding the symptoms that your trees and shrubs may experience, you can spot diseases more quickly and, hopefully, treat them before they spread, or cause larger problems. You should also talk to your local tree doctor periodically, to make sure your plants are healthy and find out what you can do to keep them that way. Contact the arborists today at Johnson Ops Tree Care to learn more!