Out, damn’d leaf spot! out I say!

So here’s a vignette that isn’t so pleasant.

Culver's Root infected with leaf spot (I think). You have to click on the photo to see the damage clearly.
Culver’s Root infected with leaf spot (I think).

Right now my garden has the worst leaf spot infection I’ve ever seen. It may have something to do with the cool, wet spring we’ve had.

At least I hope it’s leaf spot, a fungal disease, as opposed to some viral plant malady like aster yellows. I’ve had Purple Coneflowers (Echinacea purpurea) with aster yellows, and I had to pull them all out. There is no cure.

Infected Culver's Root leaves.
Infected Culver’s Root leaves.

Several species have been impacted by the leaf spot, but the worst damage seems to be with the Culver’s Root (Veronicastrum virginicum) and Anise Hyssop (Agastache foeniculum), normally problem-free plants.

Infected Anise Hyssop leaves.
Infected Anise Hyssop leaves.

In all my years of gardening, I have never once used a fungicide. Honest. However, I am considering using some kind of fungicidal or other spray as soon as I get the time.


Advice is most welcome. Do you think I am right that this is leaf spot? And how would you treat a serious case of that disease?

'Cassie' in bloom.
‘Cassie’ in bloom.

So that this will not be an entirely dismal post, let me close with a picture of our shrub rose ‘Cassie’, which is now coming into bloom. With white roses, the red Zonal Geranium (Pelargonium x hortorum) ‘Americana Dark Red’, and blue Salvia farinacea ‘Rhea’, I am all set for the 4th of July. Though I didn’t set out to create a patriotic floral display.

For more vignettes check out annamadeit’s blog, Flutter and Hum.

58 Comments on “Out, damn’d leaf spot! out I say!”

    • You should work for the State Department, you’re very tactful. I have to admit my plants are pretty crowded. Up until now it hasn’t been much of a problem, and of course I like them that way. Although from some of the comments it appears the problem may not be a fungus after all.

  1. It does not look like either a fungal nor a viral issue to
    me. I would say a larval form of some bug which has hatched, eaten and moved on. I would prune out the damaged, unless it is ongoing. Maybe an early morning inspection? Any webbing? It almost looks like some sort of aphid or spider mite you see on heliopsis.

  2. That doesn’t look like leaf spot, but like damage from a sucking insect, perhaps the four-lined plant bug. Maybe you ought to try spraying with neem oil, being sure to hit the undersides of the leaves.

    And now that I’ve “stopped by,” I want to thank you for posting all of the lovely garden photos!

  3. Jason, that looks like bacterial shot hole, I think thats in the same group as powdery mildew. You could just pick off the unsightly leaves. There are fungicides but if it was me I would not use them. I see Matts suggestion up above, maybe try that first. And I think you are right its a product of your cool wet spring.

    • I googled bacterial shot hole, but I don’t think that is it. The leaves don’t have actual holes but just areas that are black. Thanks for the suggestion, though, now I know what bacterial shot hole looks like and will keep an eye out for it!

  4. I have a few things happening right now as well but I’m with a couple of folks up there…monitor and pull off and see what happens. I do use an organic insect soap once in a while that is supposed to keep bugs off leafs that look like they are getting attacked. This after white flies were having my some of my plants for lunch and dinner. I myself have had a bit of a blow this week when an arborist came out and told me that the main maple in front of my house that my shade garden lives under has girdled root. And there is nothing we can do to save it. If it’s not one thing it’s another…good luck Jason…let us know how things go. Nicole

  5. I agree with Brenda, four-lined plant bug. They are particularly bad this year here in Minnesota. They emerge in mid May as very tiny red nymphs, each stage changes slightly. As the wings develop they are red and black, adults are black and yellow. The nymphs move slowly, get a bit faster as they mature. The adults have will sense you coming and duck to underside of leaf or drop to ground. Gotta be quick to catch and kill. Populations vary year to year, being mindful of removing their favorite host plants early in May will help control.

  6. Hi – ugly stuff, but best to id whether sap-sucking insect or fungus? If it is a fungus, I agree with Matt. I’ve been researching something organic against rose blackspot/powdery mildew. I’ve come up with a solution of bi-carb and also a solution of cider vinegar – I’ll try both.

  7. You have my sympathy and many of my plants have fallen victim to a similar scourge this year. I’m putting it down to the wet spring; (now, of course, it’s too hot and dry.) Even some of the liatris looked like your Culver’s root yesterday. This too shall pass!

  8. Glad you mentioned the aster yellows – that is not what is happening with my Purple Coneflower but I’m glad you made me aware of it. My original plants in my yard are fine but new ones have sprung up like a blanket only to have their leaves turn blotchy and white which I suspect is some kind of fungus encouraged by the cool, wet spring and overgrowth altogether. I have to get out there and get to work pulling them. And taking a close look at everything else. Thanks for the post!

  9. Oh, I can relate to frustration, mine is a “phlox bug” -what the heck-never knew they existed! I am handpicking and hoping for the best-we shall see:-( I agree the rain and cool do make a difference, I am seeing it too! Hang in there:-)

  10. Blargh. Leaf spots. So mysterious. In my community veggie plot about half the gardeners lost their tomato plants to some kind of virus; the other half have the healthiest plants you could imagine. Luck of the draw or hybrid. Who knows. I had a four lined plant bug infestation several years ago. It was a true PITA to get rid of. I am not sure it was worth the labour as it seems to be mostly an aesthetic problem rather than deadly to the plants.

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