What’s Wrong With My Dogwood?

October 3, 2013 | By | Comments (3)
Dogwood

Flowering dogwood is one of our finest native trees for blazing fall foliage. This one grows in Grumpy’s back yard. Photo: Steve Bender

Grumpy loves flowering dogwoods. He thinks that anybody who can grow them and doesn’t has a serious developmental flaw. But sometimes your beautiful dogwood suddenly doesn’t look so pretty anymore. Here are 4 common problems and what to do about them.

Problem #1 — Scorched Leaves

Dogwood

Leaf scorch of flowering dogwood. And it’s my tree! Photo: Steve Bender

Description: One day, your dogwood looks as happy as a Wall Street banker trading on inside information. 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

Dogwood

Spot anthracnose on dogwood leaf. Photo: MA Hansen, Bugwood.org

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.

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: Live with it. This fungus rarely is serious enough to warrant spraying with fungicide. Its damage is mainly cosmetic.

Problem #3 — Powdery Mildew

Dogwood

Powdery mildew on dogwood leaves. Photo: J Hartman, Bugwood.org

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 Like These

Dogwood

‘Cherokee Brave’ flowering dogwood. Soon appearing in Grumpy’s front yard. Photo: waysidegardens.com

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

Causes: 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.

Solutions: 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.

COMMENTS

  1. Steve Bender

    Glenda,

    Sorry about your trees. Borers can be a serious pest. As you’ve noticed, they usually attack dogwoods weakened by stress.

    October 11, 2013 at 3:20 pm
  2. Glenda

    Oklahoma. We lost 10 dogwood trees this past year. They were mature trees who had bloomed beautifully for years, watered through periods of drought. But the last prolonged drought and searing heat was doom for them, despite attempts at keeping them watered. The culprit that was the finale was the borers who hit once the trees were weak. Dogwood borers damage many trees in localized areas in a short period of time. Typically, trees will be stressed to begin with. The larvae germinate from eggs laid by moths and the young borers feed underneath the bark on the phloem and cambium tissue. Symptoms of borer infestation include reduced vigor and smaller blooms along with localized limb death. You should be able to see small holes in the bark where sawdust-like frass emerges. Dogwoods in sun get much more borer damage than dogwoods that are in shade all day. Control is difficult and the moths responsible are rarely seen. I first read about what was killing the trees in the Norman, Oklahoma newspaper .. and part of this comment came from statebystategardening.com.

    October 6, 2013 at 5:16 pm
  3. home, garden, life

    And don’t ever let dogwood seeds volunteer, as those specimens will be awful.

    October 4, 2013 at 1:46 pm

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