There can be many reasons for black spots on tree leaves. In this post, Rockoff Tree Solutions, your expert arborist in Boerne, explains more about leaf spot diseases and other tree leaf problems that can cause black spots.
How To Recognize the Issue
Leaf discoloration of this nature is usually easy to spot. Sometimes, the issue may be due to leaf scars rather than plant diseases if it’s not a natural identifying factor. Here, the spots will be more irregular in shape and will grow smaller as the plant heals.
If your tree has a disease, you’ll see black dots in varying sizes and shades. They may range from light tan to charcoal. You’ll likely see a darker margin or rings inside the spot. This stems from fungal infections growing outward from a central spore.
If you ignore the symptoms, the spots will join up and become splotches that can cover the whole leaf. In addition, the leaves will commonly discolor and drop before they should.
Life Cycle of Black Spots on Tree Leaves
The typical life cycle of black spots on tree leaves depends on many factors. Tree leaf health and a tree’s overall strength are the most important. A healthy tree can fight off the infection, and, with luck, it’ll die off in the winter.
The disease proves most virulent in spring, with the fungus surviving and thriving even when the leaves fall. It can spread to branches as well. Rainy weather keeps the leaves nice and moist, allowing the fungus to thrive and spread. The spores lie dormant in winter, but you must seek treatment for severe cases because they reactivate in spring.
How To Deal With This Issue
Your management strategy depends on the extent of the disease and the damage it inflicts.
Live With It
Most trees will be fine and recover by themselves. They’ll lose their leaves, but if this happens early enough in the season, they’ll grow new leaves.
However, if this becomes a recurrent problem over three years or longer, your tree will suffer real damage. If you’re heading into year two and see the issue re-emerge, call us.
Remove the Infected Leaves
It’s good practice to rake away the diseased leaves and get rid of them. You might also consider pruning affected twigs. While this won’t cure the tree, it can limit the damage by reducing the number of spores present.
Dry the Foliage
These types of fungal infections thrive in moist, humid conditions. Limit their growth by not wetting the leaves when watering. Use soaker hoses instead and only water during the early morning. Also, ensure good air circulation in the canopy so the leaves dry quickly after rain.
Support Tree Health
Black spots on tree leaves are ugly but sometimes unavoidable. You can give your tree the best chance of recovery by ensuring it has the nutrients and water it needs. Test the soil regularly and correct deficiencies.
Use a Fungicide
We recommend against this in the first year of infection unless the tree has a severe case. However, if you have a younger tree that is easy to treat, a fungicide might be a good step. You’ll need to repeat the treatment about once a fortnight, depending on the product instructions.
Get a New Tree
While drastic, if your tree sustains too much damage, this may be the best solution. It also prevents the disease from spreading.
Contact Us for the Best Advice
Are you panicking about black spots on tree leaves or wondering about other issues like, “How do trees get nutrients?” Rockoff Tree Solutions has the answers, so call us at (830) 955-0304 for a professional consultation today!