Zinnia - Alternaria (left) and Xanthamonas (right)

This plant is infected with two of the most important foliar blighting pathogens of Zinnia-Alternaria zinniae (fungal) and Xanthomonas campestris pv. zinniae (bacterial). Symptoms are very similar; pathogens can be identified by microscopy or culturing.

Fact Sheet: Leaf Spot Diseases of Floricultural Crops