Reduced sclerotial viability of Stromatinia cepivora and control of white rot disease of onion and garlic by means of soil bio-solarization

The suppressive effects of soil bio-solarization, which is a new method of soil disinfestation that combines soil bio-fumigation with soil solarization, against the sclerotial viability of Stromatinia cepivora and the subsequent control of white rot disease of onion and garlic were evaluated. Soil was bio-fumigated with fresh amendments of cow manure, chicken manure, horse manure, cruciferous plant residues, or Allium waste, at 30,000 kg/ha. After bio-fumigation, the soil was irrigated and covered with a 200 μm transparent plastic sheet for 60 days. Plots that received fresh amendment and remained uncovered and untreated served as controls. Solarization alone increased the maximum soil temperature to 55.3 °C, 50.3 °C and 46.3 °C at 10, 20, and 30 cm depths, respectively, which led to significant reductions (98.0%, 89.3%, and 62.7%, respectively) in the sclerotial viability of S. cepivora. Soil bio-solarization with cruciferous plant residues or Allium waste resulted in the strongest negative effects on the sclerotial viability of S. cepivora, with reductions of 100.0%, 98.7%, and 87.3% or 100.0%, 99.3%, and 87.7%, at 10, 20, and 30 cm depths, respectively. Compared to the non-treated control, these treatments significantly reduced the incidence of white rot disease in onion and garlic, which led to increases in onion and garlic yield in fields that were heavily infested by S. cepivora.