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.
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.
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?