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Poster: Biology & Disease Mgmt: Cultural Control


Inoculum sources of Xanthomonas fragariae in strawberry nursery packing houses: presence, viability and transmission
H. WANG (1), C. Gigot (2), N. McRoberts (2), W. Turechek (3) (1) EDISTO Research and Education Center, Clemson University, U.S.A.; (2) University of California, U.S.A.; (3) U.S. Horticultural Research Laboratory, USDA, U.S.A.

Xanthomonas fragariae causes strawberry angular leaf spot, an important disease in strawberry nursery production. When plants are dug and harvested in the field, they are transported to a “trim shed” where the leaves are removed and the roots are trimmed with table-mounted steel blades. Maintaining constant and stringent phytosanitary conditions is nearly impossible because of the sheer numbers of plants handled each day as part of this sorting and packaging process. To determine the likelihood of X. fragariae transmission during this process, PBS-soaked cotton balls were used to swab the blades and tables at nursery trim shed stations after processing strawberry plants harvested from infected fields. X. fragariae presence and percent viability were determined by squeezing PBS from the cotton balls and testing it by PMA-qPCR. The likelihood of disease transmission was estimated by rub-inoculating strawberry plants with the cotton balls. X. fragariae was detected in ~70% of the samples and ~30% of these contained living bacteria. Disease symptoms were observed in 9 of 62 strawberry plants inoculated. Results indicate that contamination of healthy plants is likely to occur during the post-harvest trimming process in nurseries and identified points where sanitation can be improved for better disease control.