Rust Fungus on Roses
Q: I have had an ongoing rose problem for about one year. The leaves on my rose bushes turn yellow and are rust-colored. I have applied a rose-fungus spray on them about every three or four weeks, but the problem continues. I recently pruned the roses and removed all the yellow leaves, including the ones on the ground. What can I do to eliminate this problem once the roses grow again?
A: Rust is common on roses, and unfortunately there's no way to completely eradicate this disease. At the first sign of rust, pick off and destroy the infected leaves, and spray with a fungicide (either organic or synthetic). Carefully follow application instructions specific to your plant; generally this is every seven to 14 days as long as conditions are favorable for infection (moist, foggy and 55-75 degrees F).
Practice good garden sanitation: rake up and destroy all infected leaves as well as prune off and destroy infected twigs. Also purchase roses that are resistant to rust. Be sure that your roses receive sunshine all day and are pruned to keep the center of the plant open. This encourages good air circulation.