Enhancing the effects of solarization-based approaches to suppress Verticillium dahliae inocula affecting tomato in greenhouse

The main concerns regarding the management of soilborne pathogens of vegetable crops through fumigants are due to their detrimental effects on the human health and environment. Due to global restrictions, soil solarization alone or combined with low-impact measures are being re-evaluated as eco-friendly alternatives to replacement of phasing-out or banned fumigants. Three experiments were performed to compare the performance of traditional and innovative films in increasing thermal performance under different partially opened or kept closed greenhouses. The effects of treatment alone or combined with Brassica pellet (Biofence®) incorporation were tested in suppressing microsclerotia of Verticillium dahliae, causing wilt of tomato and vegetable crops. Although inducing different thermal regimes at depths 15 and 30-cm depths, all films were effective in reducing microsclerotia in soil compared to the bare plots under different greenhouse conditions. The performances achieved in closed greenhouse were better than those achieved in greenhouses with the side openings kept open. In these latter conditions, green-colored ethylene-vinyl-acetate (EVA) and uncolored EVA film well performed when combined with Brassica pellet, achieving better results than those obtained in the plots mulched with film or amended alone, respectively. Smoky gray low-density polyethylene (LDPE), followed by uncolored EVA and polyamide virtually impermeable film (PA-VIF) were the most effective in reducing/suppressing V. dahliae microsclerotia within 3-to-8 weeks of treatment in closed greenhouse whereas green EVA showed lesser performance. PA-VIF and EVA green film are attractive since they may be used in combination with biofumigants or left on as mulching for weed control of crops. This paper indicates that sustainable solarization-based approaches with different films alone or integrated with Brassica incorporation can also be successfully pursued against thermo-tolerant pathogens as V. dahliae. Moreover, our findings preliminarily show that the choice of film and treatment duration should be modulated based on the greenhouse operative conditions.