Agron. Sustain. Dev. 26 (2006) 201-207
DOI: 10.1051/agro:2006016

Steam and exothermic reactions as alternative techniques to control soil-borne diseases in basil

Andrea Luvisi, Alberto Materazzi and Enrico Triolo

Dip. to Coltivazione e Difesa delle Specie Legnose "G. Scaramuzzi", Sezione Patologia Vegetale, University of Pisa, Via del Borghetto 80, Pisa, 56124, Italy

(Accepted 24 July 2006; published online 21 October 2006)

Abstract - The search for non-chemical methods to control soil-borne pathogens has recently intensified ahead of the forthcoming phase-out of the fumigant methyl bromide in 2005. Indeed, none of the previously available alternatives match methyl bromide wide-spectrum control. Here, we tested two pre-planting treatments: steaming with a soil-steaming machine and exothermic reaction by incorporation into the soil of potassium hydroxide (KOH), a substance that causes an exothermic reaction with water. Experiments were conducted from 2003 to 2005 in open-field conditions by assessing the effectiveness of steam and exothermic reaction against Fusarium oxysporum f.sp. basilici and Sclerotinia minor on basil. The results show that steam combined with exothermic reaction reduce the incidence of Fusarium wilt (77-96%) better than steam only (70-89%). The control of Sclerotinia minor was better with potassium hydroxide (94-92%) than with steam only (83-87%). Further, we evaluated the effects of the treatments on microbial population, yield and weed control. Here, the treatments induced the following major effects: (1) a reduction of more than 99% of the number of Fusarium oxysporum colonies in soil; (2) an increase of about 200% in Trichoderma spp. in soil; (3) a drastic increase in the plant yield, from 6.9-7.5 g for the control to 23.0-25.5 gr for steam treatments; (4) a high reduction of plants per square meter of 94-95% for Amaranthus retroflexus, of 96-99% for Portulaca oleracea, of 93-94% for Chenopodium spp. and of 86-90% for Hordeum vulgare, using both steam and exothermic reactions. Similar results were obtained with steam only. Therefore, our results evidence the potential of this approach to control various soil-borne pathogens. Steam and exothermic reaction are thus promising alternatives to chemical soil disinfestation for high-value crops.

Key words: basil / disinfestation / Fusarium oxysporum f.sp. basilici, Sclerotinia minor / Ocimum basilicum L.

Corresponding author: Enrico Triolo etriolo@agr.unipi.it

© INRA, EDP Sciences 2006