ABSTRACT
In addition to pathogens, plant diseases are also caused by parasites. Pathogens cause harmful deviation from normal functioning of physiological processes, whereas parasites get their food from the plant. A parasite is defined as an organism that lives in or on the cells of another organism and obtains its food from the latter without necessarily causing disease symptoms (Strobel and Barash, 1990). However, they can cause disease symptoms, probably by depleting host nutrients. The flagellated protozoa of the genus Phytomonas and some Herpetomonas spp. are parasites of plants. The parasitism of protozoa occurs without any apparent pathogenicity (Dutra et al., 2000). The parasites live mostly in the phloem and laticifers of infected plants. Such parasites can also cause diseases of economic significance in plantations of coconut, oil palm, cassava, and coffee (Dollet, 1984; Camargo, 1990). Parasites have been detected in edible fruits such as pomegranates, peaches, guavas, and tangerines (Dutra et al., 2000). Phytomonas is the important genus causing diseases. The important diseases caused by Phytomonas are described here.
