Rhizomania
(click image to enlarge) Symptoms:
• Stunting and excessive production of secondary roots
• "Wineglass" shape - healthy upper root part, constricted lower part
• Vascular system discolored and "unorganized"
Epidemiology:
• Viral disease caused by Beet necrotic yellow vein virus
• Transmitted by ubiquitous soil fungus Polymyxa betae
• Fungus is favored by near-saturated soil conditions
• Soil temperatures from 59-83° F
Control:
• Resistant varieties
• Irrigation management
• No fungicides are available for the control of P. betae