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Black Spot

Some tree conditions can really harm your trees. For example, Texas root rot can kill your healthy mature tree in weeks. Luckily if you are dealing with black spot disease, it is just a cosmetic condition that, with time, can be treated. Although there is no direct cure for black spot, it will clear in time.

It is a common misconception that black spot disease can only occur with roses; this is due to its name in the scientific community. Although “Diplocarpon rosae,” as it is scientifically known, was discovered and is common in roses, that's not the only thing it can affect. It can be found on flowers, fruits, and leaves and is problematic when the weather is hot and humid. Problems are most significant when leaves stay wet for 6 hours or more. If the conditions are right, it can attack any plant with fleshy leaves and stems. Hopefully, you are ahead of the curve on this highly contagious condition. Here is all you need to know about black spot disease.


Black spot produces round, black spots with fringed margins up to 1/2 inch in diameter. The spots form on the upper sides of the leaf. The area surrounding the spots turns yellow until the entire leaf turns yellow and falls off. Usually, lower leaves are infected first, and infected leaves often fall off the plant early. Although it isn't deadly black spot disease can give your plants, shrubs, and trees a sickly look and cause stunted growth and excessive leaf drop.

How did this happen to my tree?

Black spot disease is a widespread condition because it spreads so quickly. It will spread by wind, water, and even birds and insects traveling from tree to tree. It develops under wet, warm weather, and if neighbors have it, there is a good chance it will also spread into your yard. Once established, black spot spores can survive in the soil and on foliage that has already fallen from the tree. It is resilient enough to survive cold winter frost by covering underneath the foliage. In the spring, it will return to attack your trees and plants. As you can imagine, this makes it very difficult to remove completely. Everything around the afflicted plant must be cleaned and disposed of as soon as possible.

How to Help Your Tree:

Because its spores travel by wind and splash from leaf to leaf during watering, treating black leaf spots should be a top priority to prevent infection of the rest of your yard. During an outbreak, dispose of all affected debris. There may be better-looking options than this, but cut back all affected areas from your plants. Every bit of garden debris should be securely thrown away or burned in the fall. The spores can survive winter climates on plant material but can't stay in bare soil. The second approach to treating black spots is to treat the tree with an over-the-counter fungicide or neem oil.

How to Prevent leaf spot diseases:

Leaf spot diseases will not seriously harm your plants. Still, you can do things that, when done together, can bring the tree back to full health in the following years.

  • Be very careful when planting. Consider the total size of the plants when they are fully mature.

  • Wet conditions promote disease, so water trees at the base and avoid splashing water on leaves. Make sure the soil is allowed to dry before watering again.

  • Regular feedings provide the nutrients your plants need to grow strong and help protect them from disease.

  • Remove and carefully destroy fallen leaves before the first snowfall to eliminate locations where diseases can survive to re-infect the plant next spring.

  • Prune trees or shrubs regularly to increase light and improve airflow throughout the canopy.

If you think your plant might be suffering from black spot disease, have a trained arborist look at it as soon as possible. An arborist can diagnose the tree and provide fast, accurate solutions that will get your yard, trees, and plants looking happy and healthy in no time. In the meantime, the best thing you can do is rake all the leaves and debris out of your yard to help prevent the disease from getting worse.


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