USE OF SOIL SOLARIZATION FOR CONTROLLING BACTERIAL CANKER OF TOMATO IN PLASTIC HOUSES IN GREECE

Soil solarization provided effective control of bacterial canker of to mato in plastic houses. Trials in plastic houses in Preveza County, Gr eece, during the period 1990-1992 showed that soil solarization (appro ximately 6 weeks of soil mulching with transparent polyethylene sheets ) drastically reduced disease incidence throughout the cropping season . In contrast, soil fumigation with a recommended rate of methyl bromi de (70 g/m(2)) was ineffective. Both wild-type and antibiotic-resistan t strains of Clavibacter michiganensis subsp. michiganensis, growing o n Nutrient Agar Glycerol (NAG) medium within covered and screwed vials and embedded at various soil depths (5, 15 or 25 cm) before soil sola rization, were studied. Weekly sampling of bacteria during treatment s howed a sharp decline of populations in the solarized soil compared to the non-treated control plots 4-6 weeks after soil tarping. Populatio ns of marked strains infiltrated into tomato stem segments and buried in the soil decreased significantly after 5-6 weeks of solarization co mpared to non-treated control plots. The data presented here suggest t hat soil solarization is useful for the control of bacterial canker of tomato in plastic houses in Greece.