VIEW ARTICLE

Research.

Selective Isolation of Pseudomonas cichorii from Soil and from Leaves and Buds of Dendranthema grandiflora. J. B. Jones, Gulf Coast Research and Education Center, IFAS, University of Florida, Bradenton 34203. P. S. Randhawa, and M. Sasser. Yoder Brothers, Alva, FL 33920, and Department of Plant Science, University of Delaware, Newark 19717. Plant Dis. 74:300-303. Accepted for publication 18 October 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0300.

Two semiselective media were developed for ecological studies on Pseudomonas cichorii. The first is PCM-1, a defined medium that contains fungal and bacterial inhibitors and l(+)-tartrate as the carbon source. Most nontarget microbes in soil and plants are sensitive to the inhibitors and cannot utilize l(+)-tartrate. The second, PCM-2, is a modification of King’s medium B. It too contains antibiotics and l(+)-tartrate but also contains peptone. In a recovery efficiency study with 12 strains of P. cichorii, recovery on the two semiselective media ranged from 80 to 118% of that on King’s medium B. Selective media developed for other fluorescent pseudomonads were less efficient than PCM-1 and PCM-2 for recovering P. cichorii and suppressing nontarget microbes. P. cichorii was isolated from 11 of 41 samples of healthy-appearing chrysanthemum buds at populations ranging from 1.0 × 10³ to 1.1 × 10⁵ cfu per 25 buds. Over a 20-wk period, P. cichorii was detected on 12, 19, and 27% of symptomless leaves of chrysanthemum cultivars Bright Golden Ann, Iceberg, and Mountain Peak, respectively.