Woof. Why your dogwood tree looks so bad this year and 4 tips on how to treat it
Paul Cappiello Ph.D.
Yew Dell Botanical Gardens Executive Director
This was supposed to be a column all about the poetic and magical connection between mothers and their gardens – how starting way back in days of yore, when we were all bearskin-wearing hunter/gatherers, mothers stayed at home, raised the kids and did much of the gathering while their cavegents ran around the countryside, slaying oversized quadrupeds and pounding on their own hairy chests. It was supposed to be a heartfelt nod to mothers across the ages and their kitchen plots and their victory gardens . . . gently sharing their love of the garden with their young children on down the generations. It was supposed to be all that and so much more.
Unfortunately, there’s one mother out there who quite frankly doesn’t care whose plans she spoils – the one who does her worst and best at the same time. If she was a major league pitcher, her omnipresent curve ball would make even the New York Mets’ current pitching staff look anemic. Indeed. Mother Nature can be quite the lady . . . but then sometimes she does have her moods . . .
I often gauge the immediacy of a garden problem by counting the unsolicited emails and voicemails that greet me on Monday morning. And boy was this a Monday . . . and a Tuesday . . . and Wednesday. And all the calls started out with essentially the same story . . . “Hi. I have this fabulous dogwood in my front yard. It’s been the best tree on the block for years. It was postcard worthy last year. This year it looks sick . . . I am heartbroken.”
Watch for abnormalities
And even before I got to the office that Monday, I knew we were in for a rough run. I have neighbors down the street who do have one of those postcard-worthy dogwoods – clear, sturdy trunk, broad spreading branches and, up until this year, a killer crop of clear white blooms. They called about a week ago in a panic . . .
So I took a walk around the neighborhood and, yup, it was right there, staring me in the face. Not all, but most of the dogwoods, white and pink alike, were just plain sick. Small, stunted and brown spotted blooms . . . leaves about the same. Some trees looked fine at the top but the symptoms seemed to be worse lower in the canopy. It seemed pretty clear to me
What is Spot Anthracnose in a dogwood tree?
Now don’t panic . . . yet. The word anthracnose tends to send dogwood geeks (guilty!) into an instant panic. You see there’s another dogwood disease out there that, unfortunately, bears a very similar name – dogwood anthracnose – and this one is a big time bad actor. Once it hits your dogwood there’s little to be done but fire up the chain saw and chipper. But spot anthracnose is different.
A fungal disease mostly of the soft tissues (flowers, leaves and new stems) spot anthracnose is caused by the fungus, Elisnoe corni. It is a pathogen that hangs around, always easy to culture from dogwood stems and leaves. But most years it just hangs out, causing a spot here and there. No biggie. But some years Mother Nature decides to turn it loose.
The weather conditions that favor spot anthracnose are constant rain when the buds are first beginning to open. And this year, while our total rainfall for the year is right about average, it has come in small but constant doses. During a critical point in the spring calendar I counted measurable rainfall 13 out of 19 days! In those conditions, the usually back burner Elsinoe corni goes on a tear.
What are the symptoms of Spot Antrhacnose?
The symptoms of spot anthracnose on dogwoods are both leaf and floral spots – dark brown/purple at first, then enlarging and sometimes coalescing into larger spots with dark margins and pale tan centers. The spot centers can even fall out, leaving a shot hole appearance. It rarely kills trees unless it is particularly severe for multiple years in a row.
How can I treat Spot Anthracnose in my dogwood tree?
Control of this mostly annoying disease is quite difficult because it overwinters in the buds and stems and is then spread by spring rains as buds open. Fungicide sprays can help but need to be applied every 7 days or so through the entire bloom cycle and until all the leaves reach full size. And it’s definitely a job for a pro. Most people just let it run its course and hope Mother Nature gets it out of her system before next year. To help the process, practice good garden hygiene. Rake up and dispose of any fallen leaves this spring and in the fall to reduce some of the inoculum next spring. Mostly, just pray for better conditions next spring.
Other than that, do what you would normally do to keep your tree happy – a little (LITTLE!) mulch around the root zone and supplemental irrigation when it gets hot and dry. Don’t try to cure it with an extra dose of fertilizer.
And maybe this year, bring mom a few extra hydrangeas to distract her from the dogwoods in the front yard.
Happy Mother’s Day!
This article was originally submitted to the Courier Journal on April 19, 2022.
About the Author
Blurb about Paul here.
