Cedar-Apple Rust in spore-dispersal mode
I had never noticed Cedar-Apple Rust in nature until we moved to our current home over 22 years ago. At that time, the front door was guarded by two 40-foot-tall Eastern Red Cedars (Juniperus virginiana). Their looming presence darkened the entry and kept a creaky wooden walk slimy with algal growth, due to the minimal air circulation permitted by mis-matched azaleas huddling beneath the cedars.
After a few warm spring rains, those front Cedars suddenly sprouted alien-looking bright orange growths that were slimy to the touch. Botanists refer to the dangling fruiting bodies of this stage of Cedar-Apple Rust (Gymnosporangium juniperi-virginiae) as tentacles, but to my eye, they are more like fingers reaching out to slime any unsuspecting folks who approach too closely. The growths are cold and gelatinous to the touch, and, well, kind of gross.
This fungus completes its life cycle by alternating between two host plants — Eastern Red Cedar and members of the Apple family. The Apple family is enormous, including everything from Quince to Crabapple and Serviceberry. In my yard, I think the alternate hosts for the fungus were the sad-looking Crabapples that the previous owner had planted near the driveway, not far from the giant Junipers. The Crabapple leaves were covered in orangy spots, which I realized were the fungal growths in their Apple guise. The Crabapples tended to lose most of their leaves by mid-summer; they never bloomed well either.
After I realized what I was dealing with, we cut down the sick Crabapples. To increase air flow, we limbed up the Eastern Red Cedars, which previously had branches nearly to ground level. By the next year, the orange slimy fingers of spring were less abundant. And when we performed a major landscape overhaul to the front entry — removing those two Junipers in the process — evidence of Cedar-Apple Rust almost disappeared.
But we have a number of other large Eastern Red Cedars growing in our yard. They were here when we moved in, and I love these trees. Not only do they smell wonderful (their heartwood is what cedar chests are made from), they provide year-round cover for birds and other wildlife — and an important food source. The bluish-white berry-looking fruits on the female trees are beloved by many birds, including Cedar Wax Wings. These fruits aren’t actually berries. Junipers are conifers; the fruits are mature cones. But the birds don’t care about botanical distinctions; they just enjoy the feast provided by blue-cone-laden 40-foot trees.
This year’s humid, unusually warm April seems to have awakened quite a number of slimy orange fungal fruiting bodies. Spores travel far on winds, so they could have come from any Apple-family member in a neighbor’s yard. And when I added Serviceberry trees to my yard, I knew I might exacerbate the Cedar-Apple Rust. So far, I haven’t noticed an impact on them, but I’ll be keeping a close watch as the humid summer progresses.
If you want to grow Apples in the southeastern Piedmont, your best bet is to plant varieties that are known to be resistant to Cedar-Apple Rust and other fungal diseases. Personally, I find most fruit trees to be more trouble than they’re worth in my climate. Constant vigilance is required to protect the trees against disease and insect damage. Frankly, I just don’t have the time to watch them closely enough.
And by not needing to worry about protecting Apple trees, I can enjoy the gelatinous orange fingers of spring that adorn my big Junipers. They’re actually kind of cool — in a slimy, horror-film kind of way.
Piedmont Gardener 