Antagonistic Effects of Trichoderma Species in Biocontrol of Armillaria Mellea in Fruit Trees in Iran

Abstract

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.

Biological control of Polymyxa betae, fungal vector of rhizomania disease of sugar beets in greenhouse conditions

“…This may be due to a "crowding effect" phenomenon that occurs when the spore populations of antagonistic fungi are too high, as was previously reported by Chitarra (2003) The results of the previous studies have also shown that biological control agents are effective against damping-off, root rot, and wilt diseases of ornamental plants, vegetables and cereals, caused by Rhizoctonia, Pythium, Phytophthora, Sclerotium, Fusarium and some other fungi (Whipps 2001;Asef et al 2008;Naraghi et al 2010a, b, c;Godhani 2011;Ojaghian 2011).…”

Ability of Non-Pathogenic Fusarium oxysporum Strain Fo47 to Suppress Rhizomania Disease of Sugar Beets in Morocco

“…Under greenhouse conditions, Jakubikova et al (2010) pointed out that T. harzianum isolates with an inhibition rate of 21-68% toward the pathogenic virus (BNYVV). The results of the previous studies have also shown that BCAs are effective against damping-off, root rot, and wilt diseases of ornamental plants, vegetables and cereals (Whipps, 2001;Asef et al, 2008;Naraghi et al, 2010a, b, c;Godhani, 2011;Ojaghian, 2011).…”

In vitro compatibility of Trichoderma spp. with fungicides commonly used in cocoa ( Theobroma cacao L.)

“…Varias especies de Trichoderma han sido ampliamente estudiadas como ACB. Uno de los principales atributos de este género es la alta tolerancia a cambios ambientales lo que le permite competir y antagonizar a algunas especies de patógenos fúngicos (Reza Asef et al 2008).…”