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Fungus Among Us: Protecting Your Trees and Shrubs This Wisconsin Spring

Spring in Southeast Wisconsin brings vibrant life back to our yards, but it also creates ideal conditions for fungal diseases to take hold in our trees and shrubs. These unwelcome guests can wreak havoc on your landscaping, leaving unsightly damage and potentially weakening your plants. Let's explore some of the most common fungal foes targeting crab apple, spruce, and pine trees in the springtime, and how Hoppe Tree Service can help you keep your yard healthy.

Crabapple Calamity: Apple Scab

The culprit: Venturia species

The damage: Apple scab is a fungal disease that targets both the fruit and leaves of crabapple trees. Look out for yellow and olive-green spots on the leaves, which can pucker and fall prematurely. The fruit suffers too, with sunken, scabby patches that turn brown and become vulnerable to further threats.

Spring's wet, cool weather is prime time for apple scab to spread its spores. These spores overwinter on fallen leaves, so good sanitation is key. Rake up and dispose of fallen leaves in the fall to reduce the risk of infection. Fungicides applied preventatively in early spring before buds open can also be very effective.

Spruce Up Your Defenses: Rhizosphaera Needle Cast

The culprit: Rhizosphaera species

The damage: This evergreen fungus primarily affects spruce trees, causing browning and death of needles, often starting on lower branches. The culprit fungus overwinters on infected needles, releasing spores in spring that infect new growth.

Early detection is crucial. Inspect the base of your spruce for discoloration and needle death. Keeping trees healthy through proper watering and fertilization can boost their natural defenses. In severe cases, a fungicide application during bud swell in spring may be necessary.

Protecting Pines from Diplodia Tip Blight & Dothistroma

The culprit: Diplodia pinea

The damage: Watch out for brown or tan needles at the tips of branches, giving your pine a "flagged" appearance. This is the signature sign of Diplodia tip blight, a fungal disease that thrives in cool, wet spring weather. Stressed trees are especially vulnerable.

The best defense is a healthy offense. Proper watering, mulching, and fertilization will keep your pines strong. Pruning away infected branches in dry weather can help prevent further spread. For severe cases, a fungicide application in early spring may be needed.

The culprit: Dothistroma species

The damage: Monitor your pine trees for discolored needles, needle death, and early needle shedding. Dothistroma goes beyond aesthetics and can damage your pines by weakening them, stunting growth, and increasing susceptibility to other issues. In extreme cases, it could lead to tree mortality.

To effectively tackle this fungus, follow these steps:

  • Refrain from planting highly susceptible pines such as Austrian pine in disease-prone areas

  • Ensure proper spacing and weed control to promote good air circulation around your pines

  • Consider applying fungicide to manage the disease

Remember: Early intervention is key! If you suspect a fungal infection, give Hoppe Tree Service a call. Our team of Certified Arborists can give a proper diagnosis and treatment recommendations. With a little knowledge and action, you can keep your Wisconsin spring landscape flourishing!

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