Abstract
Twenty (20) of Verticillium dahliae were isolated from wilted potato specimens collected from six districts in Guizhou, China. All the isolates were evaluated for pathogenicity on two potato cultivars, Favorita (susceptible) and Hui-2 (resistant) using the root dip inoculation (RDI) and microsclerotia inoculation (MI). All of the V. dahliae isolates appeared to be pathogenic on both cultivars but VGZ-HZ-4 isolate gave the highest wilt incidence comparing to the others, seconded by VGZ-SC-1 and VGZ-XW-1. Combined analysis of wilt incidence resulting from using two inoculation methods for VGZ-HZ-4 and VGZ-XW-1 isolates on the two potato cultivars showed that the MI gave a higher wilt incidence than that of the RDI and cultivar Favorita had a higher wilt incidence than that of Hui-2. These two V. dahliae isolates were further used as representative isolates for mycelial inhibition (MyI) test with 33 Trichoderma isolates under a dual culture condition on potato dextrose agar plate. The 33 Trichoderma isolates consisting of 21 isolates isolated from potato soils from seven districts of Guizhou, 11 isolates from single spore isolates of the TGZ-150 isolate preserved at Guizhou Institute of Plant Protection (GZIPP) and one isolate TGZ-OLD-81 also preserved at the GZIPP. Most of the single spore isolates and TGZ-SC-4 were found to have higher MyI efficiency than that of the rest. The results indicate that the Trichoderma isolates in this study have initial modes of action of biological control to protect potato crop against V. dahlia. Key words: Trichoderma, potato wilt disease, growth inhibition, Verticillium dahliae, antagonistic fungi.
Highlights
Trichoderma species as biocontrol agents of plant pathogen were first recognized in the early 1930’s and subsequently they were applied successfully as biocontrol agents against several plant diseases in commercial agriculture (Hjeljord and Tronsmo, 1998; Harman, 2006; Schubert and Fink, 2008)
The results indicate that the Trichoderma isolates in this study have initial modes of action of biological control to protect potato crop against V. dahlia
Twenty (20) isolates of V. dahliae were obtained from the planting areas of Guizhou province (Table 1)
Summary
Trichoderma species as biocontrol agents of plant pathogen were first recognized in the early 1930’s and subsequently they were applied successfully as biocontrol agents against several plant diseases in commercial agriculture (Hjeljord and Tronsmo, 1998; Harman, 2006; Schubert and Fink, 2008). Trichoderma is a genus which include species of free- living soil fungi, opportunistic, avirulent plant symbionts (Harman et al, 2004), asymptomatic endophytes (Williama et al, 2003), and parasites of other fungi (Harman, 2006). It is often the major component of the microflora in soils of various ecosystems, such as agricultural farm soil, grassland, forest, marshes, deserts and water It possesses high reproductive capacity, ability to survive under very unfavorable conditions, efficiency in the utilization of nutrients, and capability to modify the rhizosphere. They produce a variety of compounds that induce localized or systemic resistance responses in plants (Brunner et al, 2005).
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