VIEW ARTICLE

Biological Control

Biocontrol Performance of Two Isolates of Pseudomonas fluorescens in Modified Soil Atmospheres. D. H. Kim, Department of Plant Pathology, University of Arizona, Tucson 85721; I. J. Misaghi, Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 86:1238-1241. Accepted for publication 13 August 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/Phyto-86-1238.

The incidence of tomato wilt, caused by Pseudomonas solanacearum, and the biocontrol performance of two isolates of Pseudomonas fluorescens (M29 and M40) against P. solanacearum were measured under four soil atmospheres containing O₂/CO₂ concentrations of 210:0.3 (210 and 0.3 ml of O₂ and CO₂ per liter, respectively, ambient concentrations), 180:30, 150:60, or 120:90. Altering the O₂ and CO₂ concentrations of the soil atmosphere did not cause a statistically significant (P ≤ 0.05) change in disease incidence. However, suppression of wilt by M29 and M40 was significantly (P ≤ 0.05) decreased when roots were exposed to atmospheres containing lower than ambient levels of O₂ and higher than ambient levels of CO₂. Isolate M29 significantly (P ≤ 0.05) reduced incidence of tomato wilt only under the ambient atmosphere and not under any of the three modified atmospheres tested. Isolate M40 reduced disease incidence significantly (P ≤ 0.05) only under the ambient atmosphere and one of the modified atmospheres containing O₂/CO₂ concentrations of 180:30 ml/liter.