|Connick Jr, William|
Submitted to: Environmental Contamination and Toxicology Bulletin
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2001
Publication Date: 4/1/2001
Citation: Daigle, D.J., Johnson, R.M., Sands, D., Connick Jr, W.J. 2001. Surface charge properties and soil mobilities of mycoherbicidal spores. Environmental Contamination and Toxicology Bulletin. 67:617-624. Interpretive Summary: This study of microorganisms (biocontrol agents) used to control weeds examines the mobility of these microorganisms in soil. In most soils, the biocontrol agents (fungi) are not very mobile in soil and are mostly effective only in the top two inches of soil. This information relates to environmental concerns such as water pollution because it shows in what types of soil the microorganisms are most effective and at what depth.
Technical Abstract: The surface charge properties and soil mobilities of several fungi used as mycoherbicides was investigated. The surface charge of spores of Fusarium oxysporum, Colletrotrichum truncatum, and Alternaria cassiae was characterized by electrostatic interaction chromatography (EIC) and their hydrophobic nature by hydrophobic interaction chromatography (HIC). Results from these studies indicated that F. oxysporum spores would be expected to be the most mobile spores in soil. Addition of this non-ionic surfactact Tween 20, resulted in a significant increase in mobility of F. oxysporum spores (5-60%) in hydrophobic resins. Prior to soil column studies, the extractability of the F. oxysporum spores from sand and soil was determined. Complete recovery of inoculated spores was obtained from control samples. Decreased numbers of spores were recovered from sand (38%) and from a Gilman sandy loam soil (3.5%). There was a slight influence of formulation on recovery, with a charcoal based formulation yielding slightly greater recoveries than one without charcoal. The yielding slightly greater recoveries than one without charcoal. The mobility of F. oxysporum spores was then studied in sand columns and in Gilman sandy loam soil columns. Spores were relatively immobile in sand columns, with <1% leached. In soil, the mobility was further decreased. Spores from the formulations containing carbon were slightly more mobile than formulations without carbon. The majority (99%) of the applied spores were retained in the surface layers of both sand and soil columns.