Antagonistic Effects of Trichoderma Species in Biocontrol of Armillaria Mellea in Fruit Trees in Iran
2008
Asef, M. R. (Mohammad R.) | Goltapeh, Ebrahim | Danesh, Younes
Root and butt rot caused by species of Armillaria is one of the most serious diseases of fruit and forest trees in Iran. In this study, antagonistic effects of Trichoderma in biocontrol of Armillaria were investigated. Armillaria mellea was isolated from infected roots and butts of cherry and almond trees and identified with pairing tests method. Trichoderma species were recovered from rhizomorphs and around soil of Armillaria infected roots. Trichoderma species identified were T. virens (nine isolates) and T. harzianum (three isolates). Trichoderma discs were placed onto cultures of Armillaria to study antagonistic effects. All isolates of Trichoderma colonized Armillaria colonies within 5-7 days. Volatile compounds of Trichoderma isolates inhibited Armillaria colony growth and rhizomorph formation. Mechanisms of biocontrol were investigated by light and scanning electron microscopy, these included penetration of Trichoderma hyphae in rhizomorphs, colonization of rhizomorphs by Trichoderma mycelia, colonization of apex meristemic center and apical buds of rhizomorphs, sporulation of Trichoderma in outer and inner surface of rhizomorphs, degeneration and lysis of rhizomorph tissue, and discharge of rhizomorph content.
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