Evaluation location: California, United States
Collectively, 435 F. × ananassa, 18 F. chiloensis, and 22 F. virginiana individuals (asexually propagated genetic resources) were phenotyped for resistance to PhCR in our study. The F. × ananassa individuals included 64 cultivars developed at University of California–Davis (UCD), 282 UCD hybrids (offspring from crosses between noninbred parents), 75 non-UCD cultivars, and 14 non-UCD hybrids. Thirty-eight individuals were phenotyped in 1 yr, whereas 437 individuals were phenotyped in both years of our studies. The latter were used as the “training” population for genomic prediction of breeding values and genetic variances. The training population included 321 UCD and 116 non-UCD individuals. Of the latter, 40 were wild ecotypes. The F. chiloensis and F. virginiana ecotypes were originally collected from habitats across their natural ranges in North and South America. Other than a single F. virginiana subsp. platypetala ecotype (15X001P001) collected near the Trout Creek Campground, CA (41.5° N, −121.9° W), the non-UCD genetic resources were originally acquired as single mother plants from the USDA National Plant Germplasm System National Clonal Germplasm Repository, Corvallis, OR. These individuals were multiplied from stolons in Winters, CA, and maintained in the UCD Strawberry Germplasm Collection. To produce bare-root clones (“daughter” plants) for replicated testing, bare-root “mother” plants were harvested in January, temporarily stored in the dark at −3.5 °C, and transplanted to a high-elevation (1,294 m asl) nursery in April 2017 and 2018 (Cedar Point Nursery, Dorris, CA). Clones (bare-root plants) of each individual were harvested in mid-October of each year and stored in the dark at 3.5 °C for 2–3 wk before pathogen inoculation and planting. ESTIMATED MARGINAL MEAN calculation.