ABSTRACT
This chapter provides information on diseases of sugarbeet, their symptoms, pathogen characters, epidemiology, and management. The diseases covered are aphanomyces seedling disease, damping off and root rot, rhizoctonia damping off, rhizoctonia root rot, phoma disease, cercospora leaf spot, sclerotium root rot, alternaria leaf spot, bacterial scab, and bacterial leaf spot. Hyphae are pale to dark brown, branching near the distal septum of hyphal cells, often nearly at right angles; branch hyphae are commonly constricted at the point of origin. Primary zoospores differentiate within sporangia, are extruded and encyst in clusters at the ends of long evacuation tubes from sporangial elements. Biflagellate, reniform, secondary zoospores emerge from primary zoospore cysts and, after a period of motility, these encyst and finally germinate by germ tube. Oospores survive for long periods in soil or infected plant debris. Under conditions of high soil moisture, oospores germinate by germ tube, which can directly infect the host, or produce an apical sporangium giving rise to zoospores.
