Abstract
Lettuce drop caused by Sclerotinia sclerotiorum occurres in winter season in Okinawa. We tried to inactivate the sclerotia in the soil by using polyethylene film mulching during summer season. The sclerotia buried at the depths of 10 and 20 cm were tested for their viability of germination at 10, 20 and 30 days after the mulching. Ten days later, the germination rates of sclerotia in the treated soil at 10 and 20 cm were 0.0 and 5.0 %, respectively. Twenty days later, no sclerotium at each depth germinated, and 30 days later, the sclerotia decaied. On the other hand, the germination rates of the sclerotia in the control soil remained high level throughout the treatment period.
