In the experiments described here, three biocontrol agents were tested for their ability to control root diseases. Tomato plants were raised from seed on pumice or sphagnum peat contained in buckets and recirculated nutrient solutions supplied via an ebb-and-flood system. Appropriate concentrations of the biocontrol agents Binab T (Trichoderma polysporum and T. harzianum), Gliomex (Gliocladium cantenulatum) and Mycostop (Streptomyces griseoviridis) were applied to the growing media. Suspensions of one of three root pathogens (Pythium aphanidermatum, Phytophthora cryptogea or Fusarium oxysporum f. sp. radicis-lycopersici) were applied five days later. A second application of the biocontrol agents and the pathogens was also made.
Each of the biocontrol agents reduced the levels of all three pathogens by at least 50 per cent on tomato roots growing in pumice but not in peat. The severity of the disease symptoms was also greatly reduced on plants growing in pumice and plant dry weight was increased.
Effects of Growing Medium on the Interactions between Biocontrol Agents and Tomato Root Pathogens in a Closed Hydroponic System by Khakik, Hultberg and Alsanius (2009). Journal of Horticultural Science & Biology 84 (5): 489-494. The authors' abstract of their manuscript can be seen in full at www.jhortscib.com.