Rusts (Pucciniomycotina) and smuts (Ustilaginomycotina) are the two most diverse groups of plant-pathogenic basidiomycetes. With a worldwide distribution, many of these phytopathogens are economically important, destroying many commonly cultivated crops. In this chapter we review both the historical and modern views on the classification and systematics of rusts and smuts, describe their biology and life cycles, highlight their relationship with host-defense response mitigation, and provide examples of pathogens that pose a threat to our modern agriculture. 

One of the truly remarkable features of fungal pathogens is their diverse set of approaches towards infection of various hosts across the Tree of Life. In many cases, fungi do more than simply colonize host plants, animals, and even other fungi, going one step further to manipulate their hosts in effort to increase their own fitness. In this chapter, we discuss three categories of these manipulation strategies: physiological manipulations, deception through phenotypic and chemical mimicry, and behavioral manipulation.