Understanding tree diseases


Tree diseases are difficult to understand. If you are a regular reader of this column, then you may remember me talking about the disease triangle and its importance to whether or not a disease will occur.

While it’s true that tree diseases are contagious, the disease will only affect trees of the same species.

Verticillium wilt of maples does not affect oak trees. In fact, verticillium wilt only affects trees in the maple family.

A related misconception is that powdery mildew can develop on branches and trunks and kill a tree.

Powdery mildew is a cosmetic disease and does not usually kill any plant. It may get on tree leaves, but it’s never a concern in my book.

Powdery mildew may get on a branch or stem, but I have never seen powdery mildew get on a trunk. This disease just doesn’t work that way.

Then there’s the question of chlorosis. Chlorosis is a nutrient deficiency (say of nitrogen, iron or manganese). It’s very hard to diagnose a nutrient deficiency without a tissue sample.

Chlorosis can be caused by a lot of things; it has to do with the plant not being able to get the necessary nutrients.

As far as having flowers being underneath a diseased tree, the disease will probably not spread to these healthy plants. As mentioned earlier, a disease that affects a tree won’t likely affect your flowers or other landscape plants nearby.

Diseases are host specific. They survive on specific plants. Diseases are not generalists.

That said, I mentioned verticillium wilt affects maples and plants in the maple family. Therefore, impatiens are susceptible to verticillium wilt.

However, the pathogen that causes this disease on your maple tree is not the same pathogen that causes the disease on your impatiens planted under this maple tree.

Diseases are a challenge and sometimes difficult to understand. You can count on me to teach you about them and how to manage them.

Pamela Corle-Bennett is the state master gardener volunteer coordinator and horticulture educator for Ohio State University Extension. Contact her by email at bennett.27@osu.edu.


Reader Comments ...


Next Up in

Husband finally crosses the line
Husband finally crosses the line

I drew the line at Chex Mix. I had to draw it somewhere. Had you been here to see what’s been going on in this home, you would’ve expected me to do something — anything. A lot sooner. How many wives could standby calmly and bear witness to their husband’s love affair? It started innocently enough. Taking a walk with her. Private...
3 menus we are DYING to try during Winter Restaurant Week this week
3 menus we are DYING to try during Winter Restaurant Week this week

We’ve really got to hand it to this year’s Winter Restaurant Week participants. The menus that keep rolling out are top-notch, as well as a great value. It would be almost impossible to attempt to try every Restaurant Week menu.  So to ease your foodie anxieties and help you decide, we’ve selected three menus that we think sound...
Pregnancy tests can be thrown off by timing
Pregnancy tests can be thrown off by timing

The moment a woman finds out she is pregnant can be life-altering, which makes it that much more important to conduct a home pregnancy test when it will provide the most accurate results. In fact, according to a local obstetrician, the timing of a home pregnancy test is much more vital than the type of pregnancy test a woman chooses from her local...
Obesity surgery safer than traditional treatments, study suggests
Obesity surgery safer than traditional treatments, study suggests

Having surgery to treat obesity may seem like a drastic option, but a new study suggests it may actually be a safer route than more traditional options. Researchers at Northwestern University Feinberg School of Medicine and the Clalit Research Institute in Israel, recently published their findings in the Journal of the American Medical Association...
Get fit: 3 mistakes to avoid while exercising

One of the greatest benefits of exercise is that it enables you to be more in tune with your body. During a workout you learn how your body reacts to different types of activity. Uncomfortable responses associated with exercise such as muscle soreness are normal, while other situations can be an indication of a more serious problem. Over-training and...
More Stories