Seven glasshouse experiments were set up in 1995–1999 to evaluate the efficacy of various treatments in reducing the incidence of “stanchezza” (soil sickness) of sweet basil, an emerging phytopathological problem in the main basil-growing areas of Italy. Complete or partial replacement of the soil was generally effective in increasing plant size and fresh weight of both roots and aerial parts. Steam disinfestation of the soil abolished the symptoms of “stanchezza” during the first growth cycle, but its effect was reduced on the second crop. Leaching the substrate with water and deep tilling had no or only limited effect on plant growth. Amendment with a commercial biostimulating product containing organic phenolic compounds had only partial efficacy. Bench solarization was the most effective means of control of the syndrome and its effect continued for the second crop cycle. No significant reduction of “stanchezza” was achieved with broad-spectrum antibiotic or fungicide mixtures. No significant differences were detected between bacterial and fungal populations in a soil with “stanchezza” and a non-cultivated soil. Further investigation is now required to shed light on the mechanisms underlying this emerging phytopathological problem.