Trees begin to develop leaves in spring, which means it’s time to plan for leaf disease issues you may encounter in the coming months.
Diseases in trees and leaves are often caused by bacteria or fungus, and occur when a susceptible plant is exposed to the right pathogen under favorable environmental conditions. Leaf diseases can cause leaves to die prematurely, resulting in less photosynthetic activity and therefore less energy produced for the plant. This causes stress and can eventually lead to plant death.
Here’s a look at how to treat for leaf diseases:
Types of Leaf Diseases
There are several common types of leaf diseases that can affect all kinds of trees. Make sure to know what signs to look for:
- Anthracnose: A fungal disease that can spread readily under cool, wet spring conditions. Look for dry-looking reddish-brown leaves and early leaf loss. Affects many species, especially sycamore, white oak, and dogwood.
- Apple Scab: A fungal disease that affects trees in the rose family, especially apple, pear, and hawthorn. Look for brown spots and yellow leaves. Can spread during cool and wet springs.
- Bacterial Leaf Scorch: A fatal disease spread by sap-sucking insects such as leaf hoppers and spittle bugs. Look for premature leaf browning in summer, especially in oaks and sycamores.
- Beech Leaf Disease: Caused by a microscopic nematode species present in water. Look for withered beech leaves and black spots.
- Bur Oak Blight: Fungal disease found in Midwestern states. Spreads more readily during wet seasons. Look for browning on newer leaves on bur oaks.
- Dutch Elm Disease: This famous disease comes from a fungus that affects American elms. Look for wilting and browning leaves and branch dieback.
- Fire Blight. A bacterial disease that spreads most often to fruit trees such as apple and pear. Can be spread by pollinating insects. Look for wilted and browning leaves.
- Oak Wilt: A fungus spread through roots and insects. Primarily affects red oak species. Look for leaf discoloration and defoliation in very short periods of time.
Reduce Risk Factors
The best treatment is prevention! Ensuring you eliminate risk factors and vectors for diseases to make sure they don’t become established is the best way to keep trees healthy.
Fungal diseases, such as Apple Scab, will proliferate under wet conditions. If it is an especially wet spring, check on your trees’ leaves to make sure they’re not developing signs of disease.
Diseases can be spread by insect vectors: Bacterial Leaf Scorch is spread by sap-sucking insects that attack infected trees and then move to feed on healthy trees. Treating ahead of time for woodboring insects or piercing and sucking insects, both of which can carry disease, will significantly reduce certain diseases transferring.
Ensure that growing conditions are as favorable as possible by checking on soil health, nutrients, and moisture levels. Make sure plants are being planted in their native range and in conditions best suited to their growing needs, such as levels of sun, wind, soil drainage, and soil pH (which will likely require a soil test). Depending on the risk factors associated with different diseases you’re concerned about, products may be needed. Fungal infections can be addressed with a fungicide, which may either kill the fungal pathogens or inhibit their growth. Bacterial infections should be treated with an antibiotic and insecticides will eliminate insects that can spread disease. Other preventative treatments can help improve environmental conditions, such as managing moisture levels to avoid overwatering (which can lead to root rot), or nutrient additions help aid in recovery. If you need to apply products, do so in early spring before leaves begin to develop.
Monitor Progress and Adjust Treatment
Keep watch on the development of leaf disease even after treatment, especially if diseases persist in your region or the environmental conditions that led to the disease growth remains. Diseases that are native or established in an environment, such as , require constant watch to make sure they don’t infect trees later in the season, or in the future. Some varieties of plants are more resilient to certain diseases, so it might be worth using them in place of more disease-susceptible varieties.
Leaf diseases can be a serious tree health issue, but with proper care and attention you can ensure your plants survive and thrive.
Suggested
- Propizol: systemic injectable fungicide
- PHOSPHO-jet: systemic injectable fungicide and plant resistance activator
- Arbor-OTC: antibiotic for treating leaf diseases
- IMA-jet: injectable insecticide to eliminate insect vectors of disease and fungus
- NutriRoot: help with root growth to aid in recovery