ABSTRACT
Plant pathogenic fungi can attack either above- or belowground and can significantly impair plant performance and reduce primary productivity (van Alfen, 2002). The effects of these pathogens are particularly seen in agroecosystems, especially in monocrop agriculture (Termorshuizen, 2014). Both plant pathogens and mycorrhizae in nature may play an important role in regulating plant community composition. The degree of impact of a fungal pathogen on its host plant depends on the fungal species and the environmental conditions in which the plant is grown. In many cases, the intensity of this effect is increased when plants are grown in suboptimal conditions and are already under some stress. Burdon (1993) categorizes plant pathogens as follows: (1) castrators, those with a highly significant effect on plant fecundity by affecting flowers and seed development, but little effect on vegetative growth; (2) killers, those that cause wilting and damping off of seedlings; and (3) debilitators, those that cause lesions or chronic infections. In terms of reducing primary production, all forms of pathogens can be significant, but their mode of effect is different, and the occurrence of each type may depend on the phenology of the host plant.
