Rp. Larkin et Dr. Fravel, EFFICACY OF VARIOUS FUNGAL AND BACTERIAL BIOCONTROL ORGANISMS FOR CONTROL OF FUSARIUM-WILT OF TOMATO, Plant disease, 82(9), 1998, pp. 1022-1028
Numerous fungi and bacteria, including existing biocontrol strains wit
h known activity against soilborne fungal pathogens as well as isolate
s collected from the roots and rhizosphere of tomato plants growing in
the field, were tested for their efficacy in controlling Fusarium wil
t of tomato. Tomato seedlings were treated with the potential biocontr
ol agents in the greenhouse and transplanted into pathogen-infested fi
eld soil. Organisms tested included nonpathogenic strains of Fusarium
spp., Trichoderma spp., Gliocladium virens, Pseudomonas fluorescens, B
urkholderia cepacia, and others. Specific nonpathogenic isolates of F.
oxysporum and F. solani collected from a Fusarium wilt-suppressive so
il were the most effective antagonists, providing significant and cons
istent disease control (50 to 80% reduction of disease incidence) in s
everal repeated tests. These isolates also were equally effective in c
ontrolling Fusarium wilt diseases of other crops, including watermelon
and muskmelon. Other organisms, including isolates of G. virens, T. h
amatum, P. fluorescens, and B. cepacia, also significantly reduced Fus
arium wilt compared to disease controls (30 to 65% reduction), hut wer
e not as consistently effective as the nonpathogenic Fusarium isolates
. Commercially available biocontrol products containing G. vb ens and
I: harzianum (SoilGard and RootShield, respectively) also effectively
reduced disease (62 to 68% reduction) when granules were incorporated
into pelting medium at 0.2% (wt/vol). Several fungal and bacterial iso
lates collected from the roots and rhizosphere of tomato plants also s
ignificantly reduced Fusarium wilt of tomato, but were no more effecti
ve than other previously identified biocontrol strains. Combinations o
f antagonists, including multiple Fusarium isolates, Fusarium with bac
teria, and Fusarium with other fungi, also reduced disease, but did no
t provide significantly better control than the nonpathogenic Fusarium
antagonists alone.