Some phytopathogenic microorganisms may be transmitted by water representing an efficient means way of inoculum dissemination. The objective of the work was to quantify the efficiency of thermal treatment by solar heating in the control of pathogens in contaminated water. The equipment developed for this purpose was composed of flat collectors and used both natural and forced convection to transfer heat to the circulating water. Thermostats, placed in different locataions, automatically equalized the temperature of the system. The equipment was verified to peform well at 60 ºC, in terms of water processed as well as in the eradication of economically important pathogens such as Botrytis cinerea, Colletotrichum spp., Fusarium spp., Pythium spp., Verticillium dahliae and Rhizoctonia solani. Except for F. oxysporum f. sp. phaseoli, the other pathogens were inactivated at temperatures above 55 ºC. The technique is a promising option to disinfest the water to be used in nurseries, greenhouses and in small or midsize agricultural exploitations.
