|Souissi, Thouraya - INST AGRON NAT DE TUNISIE|
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 12, 2001
Publication Date: March 15, 2001
Citation: KREMER, R.J., CAESAR, A.J., SOUISSI, T. SOILBORNE MICROORGANISMS OF EUPHORBIA FROM EUROPE AS POTENTIAL BIOCONTROL AGENTS OF LEAFY SPURGE (EUPHORBIA ESULA L.). WEED SCIENCE SOCIETY OF AMERICA ABSTRACTS. 2001. V. 41. P. 31. Technical Abstract: Little is known about the influence of edaphic factors on weed biocontrol activity of soilborne microorganisms. During an exploration of Europe for soilborne fungi and deleterious rhizobacteria (DRB) on Euphorbia species, we collected cultures from plants growing in a wide variety of soils in different landscapes. Visible plant damage incurred by insects was also noted. All cultures were screened for biocontrol activity on leafy spurge (Euphorbia esula). The objective of this report was to identify edaphic factors at collection sites that are associated with the biological control activity of soilborne microorganisms. Over 2000 rhizobacterial isolates collected from 16 sites were screened for biocontrol activity on leafy spurge using a microplate callus tissue bioassay. High proportions (>50%) of rhizobacteria classified as DRB were detected at 7 sites. Soils at these sites included sandy loam, silt loam, or clay loam and were located in flood plain, prairie, and alpine landscapes. Euphorbia spp. at sites with high DRB also displayed severe fungal disease symptoms and supported insect infestations, some with feeding damage on roots and crowns. Selected soil properties were not correlated with potential biocontrol activity of microorganisms on leafy spurge, however, insect presence and disease ratings were associated with a high incidence of DRB. This information will be useful in site selection for collecting soilborne microorganisms on weeds in their native habitat for evaluation as potential biocontrol agents.