rust disease
Red "Lipstick" Rust on Crabapples
As I was strolling through the crabapple fields in Wooster at Secrest Arboretum, I began to notice that something was significantly different than the last time that I had evaluated the trees. Since I was evaluating the trees for apple scab, it suddenly struck me that I was also looking at a lot of polka-dot covered trees! What in the world was going on? As I looked closer at the foliage, the thing that stood out the most were the number of yellow-orange dots.
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I Love Rust: Sometimes
Rust diseases of plants may of course be devastating, from black stem rust of wheat which contributed to famine after World War I to cedar apple rusts which must be controlled by orchardists and (sometimes) landscapers today. Yet, it must be admitted, they are fascinating. They can be autoecious (occurring on only one host plant) such as may-apple rust commonly seen in spring woodlands, but often they must complete their life cycles on wildly different hosts, such as wheat & barberry, juniper & apple.
About a month ago I came upon a rust disease I had not...