Vancouver 2010 Rose Show
Not the Symptom
As we tend our roses, we often see imperfections: Disease, pests, less-than-perfect blooms. Sometimes we react by treating the symptom of those imperfections instead of attacking the root cause.
Iron chlorosis, for example, is often treated by adding large amounts of chelated iron supplements to the soil. In this case, the symptom is yellowing leaves with dark green veins (leaf ribs). The cause of iron chlorosis is often high soil pH - a condition which traps existing iron in the soil, and prevents its use by the rose. The treatment, therefore, is not the application of supplemental iron, but rather the application of organic materials to bring the soil back into natural balance or slight acidification.
Likewise, fungal leaf diseases like black spot and powdery mildew can often be treated by changing the environment in which the rose is planted. Rather than reaching for the fungicide bottle to treat the symptom, consider your pruning techniques, choice of planting locations, and irrigation techniques. Did you prune so air and sunlight could circulate through the shrub? Did you plant your rose where it will receive the most sun possible? Are air and sun obstructed by buildings or dense landscape plantings? Does your irrigation system spray water over the foliage?
And there are many more like, "Why do I get aphids - especially in the spring?" Or "Why do I have sooty mold?" Or even "Why is it when I spray for one insect pest, another pops up?"
Once you begin looking for and correcting the cause of your rose pest problems, you'll find less need for pesticides - which means less work in the garden and more time to enjoy the roses you're trying to grow.
By Jan Samson