By truecarein64526365, Mar 29 2017 10:01PM
In the upper Willamette Valley we have extended periods of moisture, including, rain, dews, fogs and high humidity which create ideal situations for the fungal diseases that plague Roses. We can minimize these conditions with a few simple rules. Always plant rose cultivars known to be resistant in your area. Remember, that “resistant” does not mean completely un-affected. Always be meticulous about cleanliness around rose beds; keep old leaves and flowers cleaned up and off the property at all times. Plant roses so they are spaced to allow for good air circulation, and prune them for good air circulation. Always try to water the roots of the rose, avoiding the foliage. Water early in the morning, so that any moisture on the leaves will be able to dry thoroughly.
These are a few of the worst disease problems Roses have:
Black Spot: As the name implies, small black spots will appear on the upper surface of the leaves, causing the leaves to fall. Stems can be affected in cases of severe infection. This will weaken the plant. Black spot fungus overwinters on leaves and stems, and when the conditions are favorable; the disease will activate and re-infect new leaves in the spring. Black Spot is an annual problem and must be dealt with on a yearly basis.
Powdery Mildew: This fungus looks like a white or light gray powder or mold on the tops of the leaves. If severe, the foliage can be stunted. Spores are wind blown from plant to plant, and does not require water to survive like many of the other rose fungus diseases, so it can develop under relatively dry conditions in spring and summer as long as there is any humidity. Plants in any shade, with poor air circulation seem to be more susceptible because that sort of environment increases disease advancement.
Rust: Rust is easy to diagnose. Small fuzzy, orange pustules form on the undersides of the leaves. This fungus can also cause defoliation and over winters on diseased leaves and infected stems. Rust is most common when nights are cool and humid. These spores are spread by wind and splashing water.
Mosaic Virus: This is a systemic virus, and as with all viruses, once it is in the plant there is nothing to be done to “cure” it. Symptoms include chlorotic or yellow bands, rings, wavy lines; giving a general mosaic pattern. Sometimes mottled flower color is also noted. This disease will not move to other plants, and is generally not much of a problem. If the plant is not performing up to acceptable levels, remove it and destroy all leaves and stems. Re-plant with a certified virus free rose.
. Give us a call for a free diagnoses and estimate for treatment. 503-678-5388