Damping-Off and Stem Rot (fungi – Rhizoctonia solani, Sclerotinia spp., Fusarium spp.): A damping-off or decay of plant at or below the soil line. A dark brown-to-black lesion on stems and crown. Use sterilized potting mix. A fungicide drench will help prevent spread.
Mosaic (virus – TMV): Crinkled leaves with yellow and green areas. Plant may be stunted. Destroy diseased plants. No control.
Crown Rot (fungus – Phytophthora parasitica): A black discoloration and dry rot of the crown and lateral branches occurs near the soil line. This is followed by wilting and death of the affected plants.
Aster Yellows (mycoplasma): Plants are yellowish, bushy, and dwarfed with many rosette-like, secondary shoots. Flowers often malformed and greenish. Leaves may curl, turn yellow or purple.
Root Knot Nematode (nematode – Meloidogyne spp.): (See the section on Root Knot Nematodes)