Dogwood problems generate more worry than most, because a flowering dogwood is usually a deliberate ornamental choice rather than something that arrived on its own. When one starts spotting and dying back, people notice immediately.
This particular disease also carries a reputation earned in the 1980s and 1990s, when it moved through eastern dogwood populations hard. That reputation is worth updating.
What is dogwood anthracnose?
It is a fungal disease caused by Discula destructiva, distinct from the general anthracnose fungi that affect maples, sycamores and oaks. Our guide to anthracnose on Rochester shade trees covers that broader group, which behaves differently and is far less dangerous.
What separates this one is that it does not stay in the leaves. The infection moves from infected foliage into twigs and then into branches, producing progressive dieback. A leaf disease that stays in leaves is a cosmetic problem. One that moves into wood is not.
University of Maryland Extension notes that it was the most serious disease of dogwoods in landscapes and forests but is now less common. That is a genuinely important qualifier, and most of what you will read online was written when the picture was worse.
What does it look like on the tree?
The sequence starts earlier in the year than most tree problems people notice.
Early symptoms appear in mid to late May as leaf spots with tan or purple borders. In wet weather those spots enlarge rapidly and can kill an entire leaf. Dead leaves often hang on the twig rather than dropping cleanly, which is a useful sign.
From there the fungus moves into twigs, then branches, producing dieback that typically starts in the lower canopy and works upward. Successive wet springs make each year worse than the last.
The confirming check is on the underside of an affected leaf. Look for numerous small tan-to-brown dots, about the size of a printed period, scattered within the blighted tissue. Those are the fruiting structures producing spores that rain, dew and insects then move to healthy leaves. Their presence separates this from the ordinary leaf spots dogwoods pick up.
Field note · When to call a pro
Want a certified arborist to take a look?
Monster Tree Service of Rochester offers free estimates and a full plant health care program across the Rochester area.
Get a Free Estimate →Which dogwoods are actually at risk?
Species matters enormously here, and it is the single most useful thing a homeowner can know.
Flowering dogwood, Cornus florida, is the susceptible one. It is the native eastern species and the one most commonly planted as an ornamental in older Rochester landscapes.
Kousa dogwood, Cornus kousa, is substantially more resistant. Many of the dogwoods planted in the region over the past few decades are kousa or kousa hybrids, precisely because the industry responded to this disease. If your dogwood was planted relatively recently, there is a reasonable chance it is not the vulnerable species at all.
Site conditions matter too. Trees in cool, shaded, humid positions with poor air movement suffer worse, because the foliage stays wet longer and wet foliage is what the fungus needs.
What can be done about it?
Cultural management does most of the useful work, and it is aimed at keeping leaves dry and the tree vigorous.
Prune out dead and dying twigs and branches, cutting back into healthy wood, and remove them from the site rather than leaving them nearby. Improve air movement around the canopy where you can. Avoid overhead watering, which wets foliage exactly when you do not want it wet. Rake and remove fallen leaves rather than letting them sit, since infected litter carries the fungus forward.
Reduce other stress on the tree. Water deeply in drought, mulch properly without heaping it against the trunk as a mulch volcano, and avoid wounding the trunk with mowers and trimmers, since wounds are entry points.
Fungicides exist and are used preventively on high-value specimens, applied from bud break through the wet spring period. They protect new foliage rather than curing infected wood, they must be repeated, and on a large tree the coverage problem is real. That is a decision worth taking with someone who will look at the specific tree rather than a general recommendation.
When should a Rochester homeowner call someone about a dogwood?
The threshold is dieback rather than spots.
Leaf spots alone, in a wet spring, on an otherwise healthy tree, are worth watching rather than worrying about. Many things spot a dogwood leaf.
What warrants a professional look: twig and branch dieback progressing over more than one season, dead leaves persisting on twigs through winter, dieback moving upward through the canopy, or cankers and sunken areas on the trunk or main limbs. Those indicate the fungus has moved into wood, which is when the tree's survival becomes the question.
Because several dogwood problems overlap in appearance, a confirmed identification is worth having before spending on treatment. Cornell Cooperative Extension of Monroe County runs a diagnostic clinic that accepts samples, which is the cheapest route to certainty. Our guide to when to call an arborist about a tree problem covers what an evaluation should include.
Field note · When to call a pro
Want a certified arborist to take a look?
Monster Tree Service of Rochester offers free estimates and a full plant health care program across the Rochester area.
Get a Free Estimate →FAQ
Is my dogwood going to die from this?
Not necessarily, and species is the biggest factor. Flowering dogwood can be killed over successive seasons, particularly in shaded, humid sites during a run of wet springs. Kousa dogwood is considerably more resistant. Leaf spotting alone on an otherwise vigorous tree is not the same situation as branch dieback climbing through the canopy.
How do I know it is anthracnose and not ordinary leaf spot?
Turn an affected leaf over and look inside the blighted tissue for numerous small tan-to-brown dots, roughly the size of a printed period. Those are the fungal fruiting structures. Combined with twig dieback and dead leaves clinging through winter, that pattern is distinctive. A lab test settles it.
Should I spray my dogwood every spring?
Only on a high-value specimen, and only on a confirmed diagnosis. Fungicides protect emerging foliage rather than curing wood that is already infected, must be repeated through the wet period, and are hard to apply well on a large tree. Cultural work costs nothing and does more on most trees.
Should I plant a dogwood in Rochester at all?
Yes, and choose kousa or a kousa hybrid if the site is shaded and humid. The nursery trade shifted toward resistant material in response to this disease, so the options available now are generally better than what was planted decades ago. Our guide to trees that grow well in Rochester covers wider selection.
