Rust Diseases

We had a couple of good rains over the weekend. The weather was so nice, I had to get outside. While walking with my family, I came across a cedar that was displaying signs of rust. Cedars and junipers are the alternate host for rust diseases and are infected in late summer. The fungus overwinters in galls and cankers on these plants. In spring when wet conditions exist, spores are produced which infect prized crabapples, hawthorns, quince or other members of the rose family.

The picture above is cedar-quince rust. Spores are produced in that gelatinous material on the twig canker. They will be carried by the wind and infect nearby quince plants. The picture below is cedar-apple rust. You can see the orange, gelatinous horns containing spores that will infect crabapples and apple trees. (On a side note, there is also a bagworm hanging in the foreground. More on those tomorrow!)