What can be done about the basic leafspot diseases – mildew, blackspot, and rust – and what are the healthiest and most resistant roses?
A. These three diseases are fungal infections which flourish under warm wet conditions. Therefore – Always keep rose foliage as dry as possible – unless rinsing/rubbing off aphids or mildew or dust. Propensity to mildew can be somewhat controlled by avoiding dryness at the root and dampness on the leaves for long periods. Especially in humid summer regions, good air circulation and adequate sun are essential. Dry summer climates are less conducive to disease, though overhead irrigation late in the day can cancel this climatic advantage. If blackspot or rust appears on lower leaves, remove them – then feed and water the rose to help produce fresh foliage. Rust is by far the most serious of the three maladies if it becomes entrenched……. strip any infected leaves immediately and make sure the autumn clean-up is thorough. Above all, it is essential to feed roses well; excellent nutrition is the foundation of plant health. In our experience, the old roses are easily cultivated and cared
