Field Suppression of Fusarium Soil Borne Diseases of Tomato Plants by the Combined Application of Bio Agents and Chitosan

Two biocontrol agents, Trichoderma harzianum and Bacillus subtilis proved their high antagonistic effect against wide spectrum of plant pathogens in many previous works, two commercially formulated bio agents products, Plant guard (Trichoderma harzianum) and Rhizo–N (Bacillus subtilis) and Chitosan at 1.0 g/L were applied as seed bed treatments alone or in combination with chitosan at 0.5 g/L as foliar spray for controlling Fusarium crown and root rot (FCRR) as well as Fusarium wilt (FW) diseases of tomato plants under field conditions. Field evaluation of these treatments in an area of heavy inoculum and using cv. Super Strain indicated that all tested treatments significantly suppressed disease incidence and severity of FCRR and FW of tomato as compared to untreated controls. The most effective treatments were T. harzianum, B. subtilis and Chitosan combined with chitosan at 0.5 g/L. as foliar spray which reduced the disease incidence and disease severity of FCRR and FW of tomato. All tested treatments significantly reduced the density of Fusarium spp. in the treated soil as compared with control. The highest reduction was obtained with T. harzianum, B. subtilis and Chitosan combined with chitosan at 0.5 g/L. as foliar spray. The results showed a significant effect of all the treatments on fruit yield of the tomato plants relative to control. These combined treatments could provide sustainable management of Fusarium crown and root rot as well as Fusarium wilt in tomato under field conditions.