What's Wrong With My Flowering Dogwood?

Blooming, flowering dogwood trees celebrate spring’s arrival in the South. These native beauties can grow up to 20- to 30-feet tall and wide and have spring blooms, called bracts, in white, pink, or red. Flowering dogwood (Cornus florida) continues its beauty through the seasons, filling out with leaves in the summer that can turn shades of bright scarlet to deep crimson in the fall and produce bird-loving, brilliant red berries, and come winter, the more-bare looking tree’s horizontal branches create an elegant sculpture. If you have a beautiful, flowering dogwood in your landscape that suddenly doesn't look so pretty anymore, there are ways to revive your tree depending on what pests, diseases, or conditions it may be facing. Here are five common problems and what to do about them.

Problem #1—Scorched Leaves

Description: One day, your dogwood looks as happy as a clam. The next, the leaves turn whitish tan, especially around the edges, and start dropping. This usually happens in mid- to late summer.

Cause: Dogwood has shallow roots and doesn't like long periods of hot, dry weather. If it dries out even for a single day, the outermost leaves will scorch and stay that way or drop. If this isn't severe, the tree will recover.

Solution: Put down several inches of mulch around the base of the tree (not touching the trunk). The mulch will cool the soil and help it retain moisture. Check the leaves regularly during hot, dry spells. If you see wilting leaves in morning, water the tree immediately and thoroughly.

Problem #2—Leaf Spots

Description: Small, brownish purple spots with tan centers dot the leaves. This most often occurs to dogwoods growing under tall trees following a spell of rainy weather in summer. Diseased leaves dry and hang on through winter. Cankers forming on the twigs can eventually girdle and kill branches or the entire tree.

Cause: Spot anthracnose is a fungal disease that targets dogwoods. It spreads via water splashing the spores from leaf to leaf. It's more of a problem for understory trees than trees growing out in the open.

Solution: Remove diseased branches and leaves and throw them out with the trash. Spray healthy spring flowers and foliage according to label directions with Daconil. Repeat as soon as you see any spots appear on leaves. Also plant resistant dogwood selections, such as 'Appalachian Spring.'

Problem #3—Powdery Mildew

Description: A whitish film spreads on leaves. Affected leaves may shrivel and drop.

Cause: Powdery mildew is a fungus. There are lots of different kinds of mildew that attack lots of different plants. This particular mildew likes dogwoods. I find it generally shows up later in the growing season, usually on the newest leaves, but I have seen it in early summer too. Like spot anthracnose, it prefers trees growing in groups under tall trees. It also likes cool, rainy weather.

Solution: If it shows up in late summer, let it go. It won't do enough damage to hurt the tree. If it appears in early summer, consider spraying according to label directions with neem oil, horticultural oil, or Natria Disease Control.

Problem #4—No Blooms

Description: Your dogwood grows just fine with lots of healthy, green leaves. Just no blooms.

Cause: The most common causes for dogwood not blooming are: not enough sun (tree grows in shade, but won't bloom well there); tree dried out in summer and didn't set flower buds; tree is too young to bloom; instead of being a named selection like 'Cherokee Brave' (above), tree is labeled just "white" or "pink" and could bloom heavily or hardly at all.

Solution: Give flowering dogwood at least a half-day of sun with light shade in the afternoon. Water tree during summer droughts. Buy named selections chosen for their outstanding displays rather than unnamed trees that could do anything.

Problem #5—Chewed Holes in Bark

Description: Your dogwood has chewed holes in the base of the tree, or in more severe cases, branches are dying or falling off.

Cause: The dogwood borer, a type of moth, is feeding on the tree that’s either stressed or damaged. When bark is damaged, from things like weed whacking or mowing that strips the bark, the tree can be vulnerable to pests like the dogwood borer.

Solution: If the infestation is severe, the tree may last one or two more seasons. To control an infestation, use a permethrin-based insecticide with repeated treatments starting in early May through July when the moths are active, according to Clemson University Cooperative Extension. Meanwhile prevention is key by keeping the dogwood healthy and preventing landscaping injuries.