I feel like I’m beating a dead horse with all this doom and gloom I’ve been sharing with you about the demise of some of the trees in my garden. And I’m sorry to tell you, the drama continues! The Chicago area has gotten over six inches of rain in the last four days, with more to come, revealing something I’ve never seen in my garden or anywhere else for that matter.
You know how you know of something or someone? That’s how I regarded cedar apple rust fungus (Gymnosporangium juniperi-virginianae). I know what it is and would much rather have book knowledge of it as opposed to the up close and personal kind I’m getting on every single juniper in my garden. There are only four, and they’re all peppered with orange gelatinous bits of goo that look like some nasty little garden troll blew his nose everywhere!
I started trimming up some of the unruly limbs on the junipers around our patio when I noticed orange jelly-like blobs. Some of the bigger blobs jiggled when the wind blew. Last year, one of the junipers wasn’t looking so hot, it was actually quite ugly and I expected to dig it out this year anyway. It too was covered.
To complete the two-year life cycle, the fungus requires two hosts – junipers and crabapple trees. Their presence is most obvious in the spring when rainfall triggers the spores to swell into orange blobs. The more appropriate descriptor would be spore horns, but I think mine gives you a better idea of its actual appearance. When the blobs begin to dry, the spores are released on the wind where they seek out crabapple trees, right about the time they’re in flower. Spores can travel up to five miles before landing on a suitable host plant. Although, according to the Morton Arboretum, most infections develop within several hundred feet. You can read the full explanation of cedar apple rust and other common rust funguses here.
The spores attach to the leaves of susceptible apple and crabapple cultivars where they form hairlike growths on the undersides. Sometime in midsummer, the hairs release spores that are carried to junipers, perpetuating the cycle once again. With every infection, the crabapple is weakened, losing it’s ornamental value in the landscape as a result of defoliation caused by the fungus.
Cultural control requires the distancing of cedar apple rust susceptible species by one mile. Unfortunately, my junipers are a stone’s throw away from my Prairifire crabapple so I’ve decided to dig out two of the junipers and cut off as many of the blobs as possible from the remaining two. When I chose Prairifire, I selected it for it’s disease resistance; it received an “excellent” rating from the Morton Arboretum for its resistance to rust, fireblight, scab and mildew. For a listing of crabapple cultivars and disease resistance ratings, click here and then click on the highlighted section “Go to list of cultivars.” Once there, you’ll see a comprehensive list of crabapples and how they fared against common crabapple issues.
We’ve lived here for almost 20 years, and in that time my garden’s been relatively immune to disease and infestation. How ironic for infection to spread in the garden during this time of pandemic and quarantine. So I find it fitting to respect the tiniest organisms. They mean business.