Linderman R.G. et al. 1994

• Authors: Linderman RG, Marlow JL, Blackburn B, Mcdaniel HW
• Title: Evaluation of bacterial antagonists against Phytophthora cinnamomi in the closed-insulated pallet system (CIPS).
• Location: Phytopathology 84 (10) 1137 (1994).
• Abstract: The effect of time of incubation of soil dilution plates in an antogonism assay on the number and percentage of bacteria that inhibited several test root pathogens, including Thielaviops basicola, Cylindrocladium scoparium, Pythium irregulare, PHytophthora cinnamomi, and Sclerotium cepivorum was evaluated. Isolation were made on 10% TSA dilution plates from rhizosphere/rhizoplane soils from snapdragon or onion roots, compared to non-rhizophere soil. All colonies were removed from dilution plates as they appeared at 24, 48, 72, 96 or 120 hours of incubation at 20 C. Thena all colonies were tested from antagonism against each pathogen at 20 C on a nutrient-weak soil-extract agar amaended with 4g ground dry snapdragon root/L (SESDA). The greates percentage of antagonists occured at the 72 hr isolation. A greater proportion of antagonists was recovered from rhizophere soil than from non-rhizophere soil, and many of those bacteria were no longer antagonistic when tested at 10 C on SESDA. Bacteria from onion rhizosphere soil, as a group, were more antagonistic against the onion pathogen Sclerotium cepivorum than those from snapdragon rhizosphere soil. There data indicate that roots selectively enrich for antagonists from the soil, and that early-appearing bacteria are much less antagonistic than those that appear later.