THE ROLE OF TEMPERATURE REGARDING SCLEROTINIA SCLEROTIORUM IN THE SOIL SOLARIZATION METHOD

Sclerotinia sclerotiorum is one of the most widespread pathogens of solanacea plants in Sicily (Italy). The reduction of sclerotia in the soil is very important in achieving control of infections.

Experimental trials were carried out both in the laboratory and in the field to study effects of temperature on viability of sclerotia. Recovery and myceliogenic germination on PDA of sclerotia buried in the soil at depths of 5, 15 and 30 cm were reduced after 15 and 30 days of soil solarization and nullified after 45 days. High mortality of sclerotia was achieved after 30 days, as soil temperature increased 6–7°C more than the control and the frequency, at a depth of 15 cm, ranged between 25–30 °C for 150 hours, 30–35 °C for 377 hours and 35–40 °C for 193 hours. Similar results were obtained in the laboratory in a water bath at a temperature of 35 °C for more than 9 days, at 40°C for more than 84 hrs; at 50°C for 5–6 hrs and at 55°C for 90–100 min.

Solarization for 30 and 15 days affected recovery and viability of sclerotia in relation to depth of burial in the soil. At a depth of 30 cm few active sclerotia were recovered after 30 days of soil solarization. Recovery of sclerotia after 15 days of solarization at a depth of 5, 15 and 30 cm was respectively 32/60, 46/60 and 48/60; the viability of recovered ones was respectively 29, 45 and 52 (a.v.).