One month after the first application of A. zonatum alone, waterlettuce (Pistia stratiotes)
showed characteristic lesions on its leaves. Waterlettuce and waterhyacinth were inoculated
with the A. zonatum isolate taken from waterlettuce-infected leaves. Microscopic examination
and cultures of isolates from waterlettuce and waterhyacinth confirmed that they had been
infected by A. zonatum. None of the other plants inoculated with C. piaropi or A. zonatum
showed any sings of pathogenicity and therefore are considered to be immune to these pathogens