Common Tree Diseases: Cherry Leaf Spot vs Shot-Hole Disease
Cherry trees are a beautiful addition to any yard, but when they start showing signs of distress, it can be concerning. Two common issues that affect cherry trees are cherry leaf spot and shot-hole disease. While they may present similarly, understanding their differences is crucial for effective management. Here's a detailed guide to help you identify and treat these diseases.
Cherry Leaf Spot
Cherry leaf spot is a fungal disease caused by Blumeriella jaapii. The fungus overwinters in fallen leaves and releases spores in the spring, which are spread by wind and rain.
How To Identify Cherry Leaf Spot
It typically starts with reddish-purple spots on the leaves. As the disease progresses, these spots turn yellow, causing the leaves to fall prematurely. By mid-summer, the tree may appear as though it's experiencing an early autumn.
Conditions Favoring Disease: Wet weather significantly promotes the spread of cherry leaf spot. The fungus thrives in moist conditions, making wet springs and summers particularly challenging for cherry trees.
How To Get Rid of Cherry Leaf Spot
- Leaf Management: Over the course of the fall, rake and destroy all dead leaves to reduce overwintering fungal spores. Apply fresh mulch in January to further prevent the spread of the fungus.
- Pruning: Ensure good air circulation by properly pruning your cherry trees to reduce humidity within the canopy.
- Fungicide Application:
- Early Spring: Begin treatment with chlorothalonil (Daconil) right after the flowers fall. Spray at 7- to 10-day intervals for four weeks.
- Mid to Late Spring: Switch to myclobutanil (Immunox) or Captan, or use a combination of a half rate of Captan with a full rate of Immunox.
- Throughout Summer: Continue fungicide applications through mid-summer to control the disease effectively.
- Resistant Varieties: Consider planting cherry tree varieties that are resistant to Cherry Leaf Spot.
How To Prevent Cherry Leaf Spot
Consistent and timely fungicide applications are crucial. Preventive treatments starting in early spring can significantly reduce the impact of cherry leaf spot.
Important Note: Preventive treatment is crucial as controlling the disease becomes difficult once it is established.
Shot-hole Disease
Shot-hole disease, also known as Coryneum blight, is caused by a combination of a bacterium and a fungus. The fungus overwinters in infected buds and twigs and produces spores in the spring.
This disease is common in both ornamental and edible cherry varieties, such as the highly susceptible 'Yoshino Cherry', as well as related shrubs, such as cherry-laurel.
How To Identify Shot-hole Disease
Shot-hole disease causes small, round, reddish-brown to purple spots to appear on leaves, often surrounded by a yellow halo. Over time, the centers of these spots may fall out, giving the leaves a "shot-hole" appearance. The disease leads to premature leaf drop, usually by mid-summer, giving the tree a stressed and unhealthy appearance. In severe cases, the disease can affect twigs and fruit, causing lesions and fruit drop.
Conditions Favoring Disease: Warm, wet springs create an ideal environment for shot-hole disease. Like cherry leaf spot, this disease is prevalent in years with favorable weather conditions for fungal growth.
How To Get Rid of Shot-hole Disease
- Leaf Management: In the fall, regularly rake and destroy fallen leaves to prevent overwintering spores.
- Pruning: Prune trees to enhance air circulation and reduce moisture within the canopy.
- Fungicide Application: Preventative fungicide treatments should be applied during dormancy and early spring as new leaves start to unfold. Products containing chlorothalonil, myclobutanil, or copper-based fungicides are effective.
- Consider Replacement: If the disease recurs yearly and the tree's health declines, consider replacing the cherry tree with a more resistant species. Some cherry tree varieties have better resistance to Shot-Hole Disease and may be a good choice for replacement planting.
How To Prevent Shot-hole Disease
Although spraying large, mature trees every spring may not be practical, treating young or specimen trees can help retain leaves longer into the summer and reduce stress on the tree.
Important Note: Treating shot-hole disease late in the season is not effective, as the leaves are already infected.
How To Tell Apart Cherry Leaf Spot and Shot-hole Disease
While both diseases result in premature leaf drop, are more prevalent in damp conditions, and can stress the tree, there are key differences:
- Cherry Leaf Spot: Characterized by reddish-purple spots on leaves that turn yellow and fall off.
- Shot-Hole Disease: Causes tiny holes in leaves, with leaves looking perforated. The disease often leads to additional symptoms like sunscald and lichens due to increased sunlight exposure.
Tree Disease Management
Both cherry leaf spot and shot-hole disease can stress your cherry trees, leading to premature leaf drop and potentially shortening the tree's lifespan. Effective management through timely fungicide applications and diligent leaf removal can mitigate these issues. So, mark your calendar for early spring fungicide applications and ensure consistent follow-up treatments. With proper care and management, your cherry trees can continue to thrive and bring beauty to your yard year after year.
Professional Tree Care
Whether you need help identifying common tree diseases, applying fungicide sprays, or managing persistent infections, our team of local technicians at Miller Landscape Maintenance is here to help. With over 40 years of experience, we offer comprehensive tree and shrub care, including seasonal fertilization, disease management, tree pest control, and more. Contact our team today to learn more!
Sources:
UGA Cooperative Extension - Growing & Mowing in Bartow County