General Information: Mycoplasma-like plant pathogen. Aster yellows witches'-broom phytoplasma belongs to a group of mycoplasma-like organisms that infect plants and insects. Phytoplasmas are insect-transmitted plant pathogens that cause economically important diseases in many plant species, including vegetables, ornamentals, and fruit crops. Aster yellows is a sporadic disease of vegetable crops and is transmitted by the aster leafhopper.