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Strawberry Bacterial Angular Leaf Spot
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Dr. John Hartung and Dr. Kim Lewers

Strawberry leaves showing necrotic (dead) areas surrounded by chlorotic (yellow) areas indicative of angular leaf spot infectionIdentification of natural genetic resistance to Xanthomonas fragariae

Bacterial angular leafspot disease of strawberries has been increasing in importance to strawberry producers in recent years, because it is spread by infected but asymptomatic strawberry plantlets used in annual row culture systems. Until now there have been no control methods for the disease and no resistant varieties. We have identified four genetically distinct strains of the pathogen, Xanthomonas fragariae, and have used these strains to screen a collection of 81 strawberry accessions for resistance to the pathogen.

We have identified two strawberry genotypes that are naturally very resistant to this disease. These genotypes, US 4808 and US 4809 have been released to the public for use in developing elite Close-up of a strawberry leaflet with oozing bacterial lesionsstrawberry cultivars with innate resistance to this disease. Use of this germplasm may contribute to more sustainable and profitable strawberry culture.

Workers in our lab have characterized the population structure of this pathogen and developed three independent PCR-based assays for the pathogen that can be combined and performed simultaneously in a multiplexed manner. This assay has been adapted to testing of plant material.

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