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Biocontrol evaluation of
wheat take-all disease by Trichoderma screened
isolates
Doustmorad Zafari1*, Mehdi Mehrabi
Koushki2 and Eidi Bazgir3
1Department
of Plant Protection,
Agriculture Faculty, Buali Sina University, Hamadan
Province, Iran.
2Laboratory
of Quarantine and Plant Pathology, Agriculture Jihad
Organization, Markazi Province, Iran.
3Department
of Plant Protection,
Agriculture Faculty, Lorestan University, Lorestan Province,
Iran.
*Corresponding author. E-mail:
doustmoradzafari@gmail.com. Tel: +98-09183605425. Fax:
+98-08613134321.
Accepted
23 June, 2008 |
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Wheat
take-all disease, caused by Gaeumannomyces graminis
var tritici (Ggt), has been observed in
different areas of Iran in recent years. Current biocontrol
studies have confirmed the effectiveness of the
Trichoderma species against many fungal phytopathogens.
In this study, biocontrol effects of Trichoderma
isolates were evaluated against take-all pathogen. Five (Trichoderma
virens T65, Trichoderma virens T90,
Trichoderma virens T96, Trichoderma virens T122
and Trichoderma koningii T77) isolates were selected
after screening tests for antifungal effects against
take-all pathogen and three (Trichoderma koningiopsis
T149, Trichoderma brevicompactum T146 and
Trichoderma viridecens T150) isolates were used as
random selection. Also, Trichodermin B and Subtilin as
commercial bioproducts were also used to evaluate biocontrol
effects against take-all in greenhouse. In dual culture
tests, five (T65, T90, T96, T122 and T77) isolates covered
and colonized the colony of the pathogen. Microscopic
studies revealed hyphal coiling (hyperparasitism) of
isolates T65, T96 and T90 around Ggt hyphae. Culture
filtrates and volatile metabolites of all isolates reduced
the mycelial growth of take-all pathogen. T96, T65, mixture
of eight isolates and Trichodermin B were more effective
than other treatments to control the disease and reduced 25
to 55% disease severity and increased 27 to 59% dry weight
of shoots and 23 to 58% dry weight of roots compared with
control while disease reduction of seed coating method was more than soil treatment
application.
Although, based on shoots and roots dry weight, all of
treatments showed significant differences with healthy
plants.
Key
words:
Biocontrol, mycoparasitism, Trichoderma, take-all,
volatile and non volatile metabolite. |
