R. J. Cook

Diseases Caused by Root-Infecting Pathogens in Dryland Agriculture

This chapter is concerned with the diseases of roots, rootlets, and root hairs-portions of the plant that cannot be seen except by special observation techniques or by destroying the plant. Specifically, I focus on those diseases caused mainly by fungi (Fusarium, Gaeumannomyces, Pythium, and Rhizoctonia spp.) nematodes, and to a lesser extent bacteria that infect through roots and complete part or all of their life cycle in root tissues or in soil surrounding the roots (the rhizosphere). This includes the vascular diseases (wilts) caused by fungal (Cephalosporium, Fusarium, Verticillium spp.) and bacterial pathogens that gain entry into the vascular system of plants through root infections, but does not include the leaf spots and other above-ground plant diseases caused by pathogens such as Ascochyta and Septoria spp. that use crop residue on the soil surface as a springboard for attack of the leaves.