ARS | Publication request: Protocol for maintenance of Synchytrium solstitiale, cause of false rust on yellow starthistle, under greenhouse conditions

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: March 26, 2008
Publication Date: June 1, 2008
Citation: Eskandari, F., Bruckart, W.L., Widmer, T.L. 2008. Protocol for maintenance of Synchytrium solstitiale, cause of false rust on yellow starthistle, under greenhouse conditions. Phytopathology. 98(6,Supplement)S214-215

Technical Abstract: An isolate of Synchytrium solstitiale was collected in France and sent to the FDWSRU to evaluate as a candidate for biological control of yellow starthistle (YST, Centaurea solstitialis). Procedure was needed for maintenance of the pathogen in the greenhouse before other research was possible, since inoculum is available from France only a few months of the year. Leaf pieces, 1-cm^2, with galls were placed at the center of YST rosettes to provide inoculum in this study. YST growing either in pots or whole plants growing in flasks of water (soil was washed from roots) were inoculated as described and placed either in a Percival growth/dew chamber (10 C, night and 15 C, day; 8 hr photoperiod) or in a 13 C conventional dew chamber with continuous light (40 watt incandescent light bulb). Plants put into the Percival were enclosed in plastic bags and misted daily to maintain free moisture on leaves; moisture in the other dew chamber came in the form of dew. After 10 days, plants were removed from the chambers and placed in a 20 C greenhouse with shading. Plants were rated weekly for gall formation, development of resting spores, proportion of infected leaves, and disease severity (a general visual rating of disease). Regardless of variable, whole plants in flasks that were in the Percival chamber developed significantly more infection than those in pots or in the conventional dew chamber. These differences may be due to the fact that rosette leaf bases are submerged in the water and susceptible tissue may be more easily accessed by zoospores. Regardless, it has now been possible to maintain S. solstitiale artificially in the greenhouse for over a year following these protocols.