ABSTRACT
Although most of the important plant pathogen groups have been covered in previous chapters, a few remaining plant pathogens or organisms that have been associated with disease symptoms are parasitic seed plants, protozoa, algae, and mosses. The most important pathogens among these groups are the parasitic seed plants. Parasitic seed plants have flowers and produce seed, but may be deficient in other typical characters associated with plants such as roots or chlorophyll. Some parasitic seed plants, such as buffalo nut (Pyrularia pubera), are shrubs that have green leaves and a root system whereas others, such as squawroot (Conopholis americana), Indian pipe (Monotropa uniflora), pine-sap (M. hypopiths), witchweed (Striga lutea), dodder (Cuscuta species), and dwarf mistletoe (Arceuthobium species) and leafy mistletoe (Phoradendron species), have a very small thallus and do not have roots or green leaves, or both. In this chapter several examples of parasitic seed plants, tropical protozoa that have been associated with several diseases, an alga whose colonies are associated with leaf spotting of magnolia and
azalea, and ball moss that causes death of shrubs and trees in isolated areas of Louisiana, Texas, and Florida will be considered.
