The fungus Trichoderma harzianum is a biological control organism against a wide range of soil-borne pathogens and induce plant growth capacity. It has been shown that T. harzianum stimulated the growth of tomato plants (McGovern et al, 1992; Datnoff and Pernezny, 1998). In addition, T. harzianum is well documented as effective biological agents for R. solani control in soil (Howell, 2003). Application of small non-effective doses (1-2 μg/kg) of Pentachloroniitrobenzene (PCNB) to soil along with a T. harzianum preparation (2g/kg) decreased the incidence of eggplant damping off caused by R. solani from 13 to 40%, while T. harzianum alone reduced disease incidence by 26% (Hadar et al., 1979).
Windham et al. (1989) reported reduced egg production in the root-knot nematode Meloidogyne arenaria following soil treatments with T. harzianum (T-12) preparations. The combination of sublethal heat treatment dose and T. harzianum, enhanced control of disease on beans (by 90 to 100%) under greenhouse conditions (Elad et al., 1980).
Barakat and Al-Masri, (2009) studied the effect of the biocontrol agent T. harzianum (isolate Jn14) in combination with an amendment of sheep manure on the soil suppressiveness of Fusarium wilt of tomato over a 28- month period. They tested a combination of T. harzianum and organic amendment at the concentrations (w:w) of 6 and 10%; this reduced tomato wilt by 21–36 % and 29–36% respectively, after 0–28 months of soil incubation. When the amendment was added at the lower concentrations (2%), the wilt was suppressed only after 18–28 months.
Noble and Coventry (2005) showed also that the combination of T. harzianum and organic amendment can be used to control soilborne pathogens including R. solani. Increased growth response has been demonstrated by several other investigators (Altomare et al., 1999). They demonstrated the ability of T. harzianum to solubilize insoluble tricalcium phosphate in vitro. Several other Trichoderma spp. were formulated as well, in commercial production for the protection and growth enhancement of a number of crops in several countries (Mcspadden & Fravel, 2002).
