Rhizome Rot (fungus – Sclerotium rolfsii and Fusarium spp.): These organisms cause rhizomes to decay and stems to rot at the base. A cottony fungal growth may be present in rhizome rot.
Bacterial Bud Rot (bacterium – Xanthomonas cannae): Young shoots and leaves may be killed. Control of these organisms is through selection of healthy rootstocks. Damaged roots should be discarded. Plantings should be thinned periodically and replanted to increase vigor.
Mosaic (virus): Irregular light- and dark-green areas in leaves. Plants may be stunted and late in flowering. Destroy infected plants and control aphids. The variety – President is immune.
Other Diseases: Include Fungal Leaf Spot (Alternaria spp.) and Root Knot Nematodes (Meloidogyne spp.).