Effect of soilpH and temperature on the biological control of Rhizoctonia solani by Bacillus megaterium and Trichoderma harzianum

The root rot and seedling blight of soybean, caused by Rhizoctonia solani isolate 2B-12 and controlled by Bacillus megaterium and Trichoderma harzianum, was the disease/biocontrol model used for a systematic study of the effect of soil pH and temperature on the biological control of soilborne plant pathogens. In vitro experiments showed that T. harzianum isolate Th008 was antagonistic to R. solani and compatible to B. megaterium strain B153-2-2. Under greenhouse conditions, disease was more severe at soil pH 7.0 than 5.5 and at soil temperature of 25 C than at 15 or 35 C. Trichoderma harzianum and Bacillus megaterium achieved disease control, but it was dependent on soil conditions. When antagonists were used in combination, a synergistic effect was observed at soil pH 5.5, but not at pH 7.0. Bacillus megaterium was responsible for the improvement of root colonization by Trichoderma harzianum, especially at soil pH 5.5. Rhizosphere colonization by T. harzianum, when it was alone, was more effective at soil pH 7.0 and high temperatures than at pH 5.5 and low temperatures. Soil populations of B megaterium increased with increase of soil temperature. The study shown that the system of host/pathogen/antagonist/environment exists in a very delicate balance, which knowledge may permit the improvement of biological control of soilborne pathogens by introduced or indigenous antagonists.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Crop Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Dal Soglio, Fabio Kessler

Contributors dc:contributor

• Eastburn, Darin M.

• Biology, Microbiology
• Agriculture, Plant Pathology

Statement dc:rights

• Copyright 1995 Dal Soglio, Fabio Kessler

Language dc:language

eng

Identifier

AAI9624331
(UMI)AAI9624331

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21766