With the wet, warmer spring weather the arborists in the Wichita area have been receiving calls about unusual, jelly-like growths on Cedar trees. The growths are the spore-producing galls from a disease called Cedar-Apple Rust. The spores, produced on Cedar trees, will be blown in the wind to infect Apple and Crabapple trees.
Cedar-Apple Rust is an alternate-host disease of trees and shrubs. The spores produced on Cedar trees infect Apple or Crabapple trees. Conversely, the spores produced on the Apple or Crabapple trees infect Cedar trees. Arborists can reduce Cedar-Apple Rust infection on Crabapple trees, but the fungicide treatments must be started soon after the Crabapple begins to leaf out. Two to three follow up treatments will be necessary to fully protect the Crabapple tree from Cedar-Apple Rust.
Unprotected Crabapple trees are not likely to be killed from Cedar-Apple Rust, but it will cause noticeable defoliation of the tree early in the summer. Infected trees should receive extra care such as watering, feeding, or mulching to minimize the impact of the disease.