Plant Diseases
Strong evidences support that some flagellate protozoa cause disease in plants although their pathogenicity could not yet be determined, similar to phytoplasma (=MLOs) and some fastidious vascular bacteria, via Koch's postulates.

Pathogenic protzoa apparently cause phloem necrosis disease of coffee, hartroot disease of coconut palm, and sudden wilt disease of oil palms. All three diseases so far known are confined only in South American countries.

(ii) Hartroot disease of coconut palm

is caused by members belonging to genus Phytomonas which occur in mature sieve elements of young leaves and inflorescences.

This disease spreads very rapidly and kills the plants. So far, however, no any such agent is known which transmits the disease.