O Zeidan, Y Hadar, I Chet

Including onions in crop rotation reduced damage in crops susceptible to Sclerotium rolfsii. In peanuts grown after onions, disease incidence was reduced 62% and pod yield was increased 15–52% in field experiments. Onion cultivars showed distinct differences in their ability to reduce the incidence of S. rolfsii infection. Disease suppression detected 4 mo after planting onions in infested soil lasted for a year. Sclerotia buried in an onion field were 42% less viable than the control. Onion bulb extract or root exudates inhibited both sclerotial germination and mycelial growth. The inhibitory compound, with a molecular weight of less than 5,000, was heat-sensitive. Integrating onions in crop rotation in S. rolfsii-infested fields is potentially an inexpensive means of disease control.