Rust (fungus
- Tranzschelia discolor): Initial symptoms are minute yellow spots on the
upper leaf surfaces. As the fungus develops, reddish to dark brown colored rust
lesions break open on the lower leaf surfaces. The specific rust fungus attacking
plums does not attack peaches. Rust is usually a late season problem that causes
rapid defoliation. If defoliation is repeatedly premature, production can be affected.
Chemical control is a viable option but generally not necessary.
Bruce and Morris are susceptible. Methley, Santa Rosa, Ozark Premiere and Allred
are tolerant or resistant.