Verticillium Wilt: The Soilborne Disease Claiming Victim(s)

For nearly 17 years, my garden flew under the radar of disease until last year when it was obvious something was wrong with my redbud tree (Cercis canadensis). One of the main branches didn’t flower or leaf out. While I remained hopeful, the reality was that I sort of knew what was happening but didn’t want to admit it to myself. It was kind of like saying Beetlejuice! three times. Only this was even harder, this was real and attacking my favorite tree.

I sawed out the affected branch and waited for another spring, hoping it might bounce back but it didn’t. It got worse. Verticillium wilt has consumed two-thirds of the tree and right now, only the branch closest to the gate has flowers. The rest is dead. So I’m enjoying that last branch while at the same time lamenting the loss of the very first tree I planted in my garden.

Verticillium wilt is a soilborne fungus that attacks over 300 plant species (here’s a list). Redbuds are one of its favorites. I don’t know how it arrived, perhaps in the soil of another perennial I planted in the bed. Or maybe it was always there, waiting. But once you’ve got it, it’s there for the long haul and there’s very little to be done about it. Aside from solarizing the area, which takes far too long and would require the removal of a lot of plants, options are limited.

Fortunately, there are plenty of options that are resistant to verticillium wilt, none of which is as lovely as the redbud. I’ve tried to be conscious of disease transmission and clean my pruners and loppers regularly, but probably not as often as I should. Hopefully, it wasn’t gardener negligence that introduced this nastiness to my garden.

Whatever the cause, it’s here and I’m concerned for the rest of my garden, especially since my daughter noticed several dead branches on the Little Twist cherry tree (Prunus incisa) planted along the front walk. Plants in the prunus family are on the list of susceptible plants and my heart sank again. It didn’t flower last spring and I attributed that to a late and harsh cold snap. It leafed out just fine and I didn’t think about it again since it flowered beautifully a few weeks ago. It’s nowhere near the redbud so I remained positive until last week.

With clean pruners, I cut out the dead branches to see if they had the dreaded darkened center typical of plants infected with verticillium. Sure enough, they did. I compared a dead branch with a healthy one and the only difference was this circular discoloration. I’m not going to take it down, but instead wait it out to be certain that it’s curtains for Little Twist too.

And now I’m concerned for the rest of my garden, particularly the west border along the fence. Our home is on a sloped lot. Directly down hill from the redbud tree is a serviceberry, then two Beijing Gold Peking Lilacs and finally a Black Lace elderberry whose buds are swelling. Every single one of these beautiful specimens is on the list of plants susceptible to verticillium wilt. How devastating that would be to lose this border. While others may see it as an opportunity to try a new tree, for me it would be a crushing blow.

The thought of it just makes me so sad.