Physocarpus, Heal Thyself

So last night I went to the first class of the new course I’m taking at the Chicago Botanic Garden, “Introduction to Plant Health”. Actually, I thought it was the first class – really, it was the third class. I was confused about the date due to the parallel space-time continuum I enter whenever there is a period of insane busyness at work. I hate it when that happens.

This course is a requirement for the certificate in garden design that I’m pursuing, but I’m a little apprehensive about taking it. That’s because when it comes to plant health, I could probably be sued for negligence. When a plant in my garden has serious health issues, my usual response is to just get rid of it. I mean, illness is such a downer.

Rust on a hollyhock leaf. Pretty disgusting, huh?

Sometimes you really have no choice in the matter, such as when your purple coneflowers (Echinacea purpurea) are infected with the incurable aster yellows. However, when my hollyhocks (Alcea rosea) developed rust, I didn’t try to save them with fungicides, I just pulled them all out. I still miss those hollyhocks, but I got rid of  them all the same.

My other approach to plant diseases: ignore them. You say there’s downy mildew on the Monarda? That’s funny, I can’t see it.

I have made some attempts to actually bring stricken plants back to health. For instance, I used to have a small Magnolia, not sure what species, in the backyard. The Magnolia became badly infested with soft  scale insects. Soft scale are pretty disgusting because they produce a sticky substance called honeydew. The honeydew in turn feeds sooty mold, which unlike honeydew is aptly named.

Magnolia scale. Also disgusting, even before the sooty mold gets all over everything. Photo: Missouri Botanic Garden.

After consulting the internet, I tried to apply a dormant oil to smother the scale. Apparently timing is important with applying dormant oil and I got the timing wrong, because the scale bugs and their friend Mr. Sooty Mold didn’t go anywhere. My patience exhausted, I cut down the Magnolia, replaced it with several Spicebush (Lindera benzoin), and have not seen any scale since.

I’m proud to say that I once did cure a plant of what ailed it. Earlier this year, some of the stems of my Forsythia were dying back. Using a book called What’s Wrong with My Plant? by David Deardorff and Kathryn Wadsworth, I figured out that the stems were infested with borers. Cutting the stems back below the infested areas did the trick.

Actually, I really haven’t had much in the way of pest or disease problems in my garden over the years. I put that down to growing tough plants in the right cultural conditions, along with a very healthy population of beneficial insects. That may not always be enough, however. For example, in that first class the instructor warned of the high probability that crabapples will become diseased. I love my crabapple, and I don’t want to cut it down.

So I hope that after this class I can do something other than tell my plants to cure themselves.

What about you? Do your plants get sick much, and how do you handle it when they do?

20 Comments on “Physocarpus, Heal Thyself”

  1. I have to say, no, my plants don’t seem to get sick, but if something is, then it gets taken out. We have so many beneficial insects as we don’t use sprays and it seems to work. Good luck with the course.

  2. Mildew seems to be an annual problem with the lilac but it doesn’t seem to do any harm. Over the years, the peonies have developed mildew but I’m tired of them and will probably yank them out next spring. My honeysuckle vines suffer from some kind of problem (aphids?) but they are still standing. The bag worms in the arborvitae I did pick off, day after day, until I could find no more – they would have destroyed the plant. Usually when my other plants look sick, they just need more water. My question: why don’t weeds get sick and die? They are so robust!

  3. Plant diseases sometimes are easier to prevent than cure, and removing an infested plant may be best for the health of a garden. My one success in curing a disease was when my azaleas developed leaf gall. I was able to get rid of that by diligently removing all the infected leaves.

  4. I am much like you – I just stare at it, until it gets so bad that out the plant goes. Except once I had scale on one of my roses. I waited, – the rose really suffered – but I wanted to keep that rose, so then I tried to kill the scale, which only made them move to the salvia. But then, I could deal with them – I got rid of the salvias!

  5. I have a love/hate relationship with the book What’s Wrong With My Plant. It’s great at helping you identify the problem, but not too helpful in solving it. “Prevention” is their favorite solution, but that doesn’t work when the plant is already diseased! I can ignore a lot, but if I’m looking it up in Dearsdorff and Wadsworth, it’s a little late to “provide better growing conditions” !
    Wow. I feel better now.

  6. I have never wanted to fuss over plants once they are in the ground, one of the many reasons that I prefer native plants. I figure that, if a plant gets diseased, it wasn’t planted in the right place. If the plant eventually recovers, I chalk the rough spell up to a period of stress, often weather-related. If it doesn’t survive, I look at it as a learning opportunity and a chance to try something different. That said, by using native plants and paying attention to their needs as to growing conditions, and by letting nature provide pest control, my plants do incredibly well without a lot of intervention from me, the gardener.

    • I agree with your general approach, and my experience has been similar. However, there are some exceptions, and I’d like to see if I could be better equipped for those. Also, I’d like to be able to work with people who have a more conventional approach to gardening.

  7. Knock wood, I do not have too many issues. I think if you grow a lot of species and avoid the harsh chemicals your garden can more or less reach a balance between the good and the bad. I do avoid putting anything in that I know has issues.

    That said, I fought a hard brown scale for years on a favorite redbud. When the tree was small I would just get on a ladder and fun my hands along the branches squishing as I went. I could only do a few branches at a time before my gag reflex engaged. Now that the tree is too large, I reach for a bottle of systemic drench that you pour around the base of the tree, definitely not organic, but it works for an entire year and only affects a limited area.

  8. My plants are a pretty healthy bunch but I have lost cone flowers to aster yellows and had a rue collapse on me this fall. Most disease develops when a plant is stressed or disease prone. If I can solve the initial problem by moving them, etc, then I will. If not, out they go. Diseased plants cause plant stress in neighboring plants by releasing a distress pheromone. I don’t mind sacrificing a few to save the whole. 🙂 Your class sounds really cool. I occupy that same parallel universe. I thought you looked familiar!

  9. We’ve got a stand of hollyhocks in the front and although they looked very stately when they were in full flower, closer inspection revealed that they were full of rust. I just couldn’t keep up with the spraying. Added to that, every time I did spray, the rain would wash it all off shortly after (usually within hours). In the end, I settled for cutting off the worst. I’m not sure what I’m going to do next year (i.e. take them all out or have the same show)

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