Bur Oak Blight
Have you noticed black spots on oak leaves? Are they turning brown, developing notched edges, or hanging on the tree through winter instead of dropping in the fall? It may be from a condition called bur oak blight. This is caused by a fungus that thrives in cool, wet spring weather and infects the leaves […]
Cedar-Quince Rust
Do you have bright orange, gooey, or spiky growths on your cedar or juniper trees? It may be from a condition known as cedar-quince rust. Small, pale-yellow spots appear on leaves that enlarge and turn orange-red over time. The Problem Cedar-quince rust spreads when galls on junipers release spores in the spring, which are carried […]
Diplodia Shoot Blight
Have you noticed spring dieback in tree shoots or whole branches slowly declining over time? This could be a sign of a diplodia shoot blight. The Problem This disease spreads in spring when spores infect newly expanding shoots. While healthy trees can often stop the infection early, stressed trees may experience more serious damage over […]
Gall Wasps
Have you noticed bumps on oak tree leaves or swellings on twigs or leaves—especially along the midrib of the leaves? Your oak tree may have gall wasps. The Problem Gall wasps lay eggs in twigs or leaves, causing the tree to form protective galls around the larvae. Some larvae live inside twig galls for 2–3 […]
Iron and Manganese Chlorosis
Do the leaves on your tree seem more yellow these days? It may be from a condition known as iron and manganese chlorosis, where leaves yellow because of the destruction of chlorophyll and/or the lack of its production. The Problem Iron and manganese chlorosis reduces chlorophyll in leaves of affected trees due to insufficient iron […]
Magnolia Scale
Have you noticed sticky leaves and sooty mold on magnolia tree twigs? It may be from a condition known as magnolia scale. It may also cause fewer or smaller flowers and leaves than what you usually enjoy. The Problem Dark gray nymphs overwinter, creating a red-brown median ridge on older twigs. Females give birth to […]
Maple Tar Spot
Have you noticed black spots on maple leaves? It may be from a condition called maple tar spot. This is caused by wind-borne spores traveling from fallen leaf litter to newlydeveloping leaf tissue. The Problem Three species of Rhytisma can cause different lesions that begin as small light green/yellow spots on leaves that gradually increase […]
Nectria Canker
Have you noticed red spots on tree bark, especially after rain or in damp weather? It may be from a condition known as nectria canker. It can cause damaged areas on your tree that will seem to be getting worse instead of healing, especially around old pruning wound or bark injuries. The Problem During rain […]
Oak Wilt
Have you noticed sudden leaf drop in oak trees in your yard or neighborhood—even when they seemed healthy earlier in the season? This could be a sign of oak wilt. The Problem Oak wilt is a serious fungal disease that spreads either underground through connected tree roots or aboveground by sap beetles carrying spores from […]
Pine Bark Adelgid
Have you noticed white cotton on pine trees, or cottony patches on the trunk or branches that look like snow or mold? It may be from a condition called pine bark adelgid. This is an infestation of reddish-brown insects that hide beneath the waxy coating. The Problem Pine bark adelgids spend the winter as immature […]