On poinsettia, look for white or yellow spots on upper leaf surface. Monitor closely in areas with poor air circulation, high humidity or drafty places with more temperature fluctuations between day and night temperatures. Inspect geraniums more closely during warm weather. Look for vascular discoloration. Plants may wilt and die.
All geraniums are susceptible.
Do not place ivy geraniums over geraniums. When infected, they often do not show any distinct symptoms, perhaps only loss of vigor, and will serve as innoculum source. Monitor areas closely with geraniums from different suppliers present. If possible, buy from one supplier. See Sanderson, J, P. Davis, and R. Ferrentino.