Systemic Movement of Agrobacterium tumefaciens in Symptomless Stem Tissue of Chrysanthemum morifolium. J. B. Jones, IFAS, University of Florida, Gulf Coast Research and Education Center, 5007 60th Street East, Bradenton 34203. B. C. Raju, Weyerhaeuser Tissue Culture Laboratory, 4051 Fudge Road, Apopka, FL 32703.. Plant Dis. 72:51-54. Accepted for publication 2 September 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0051.

Agrobacterium tumefaciens was isolated infrequently from apparently healthy stem tissue distal to developing galls. The incidence of recovery of A. tumefaciens ranged from 0 to 80% from stems of different cultivars 2 wk after inoculation. The bacterium was isolated from only 11.4% of the 377 stems assayed. Wounds were made aseptically above the developing galls, and gall development occurred in 2.2% of the 1,400 sites. In one study, when stems of six cultivars were wounded, galls developed on stems of only three of the cultivars. The percentages of inoculated stems that developed galls were 44, 14, and 2% on the cultivars Dark Yellow Paragon, Florida Marble, and Circus, respectively. In a second study, the incidence of gall development at wound sites was 4% on Matador stems wounded 1 day after inoculation. However, gall formation was not detected on stems of Matador plants wounded 0, 3, or 7 days after inoculation or at any of the wound sites on Circus Bronze stems that were wounded at the same time periods. When cuttings were taken from inoculated Surf and Circus stock plants, the incidence of gall development ranged from 0 to 60% on the cut ends of the stock plants and from 0 to 40% on the bases of the cuttings. Generally, gall formation was not induced on the wound surface of the stock plant (4.4% of 160 wound surfaces developed galls) or the cutting (3.1% of 160 cuttings developed galls) when cuttings were taken at locations on the stem above developing galls.

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