Rosa 'Radsunny'

Summary

UC Davis is located in Davis, California, this site has a silty clay loam soil and plants are irrigated with potable water. More information about the field sites is located in the Nuts & Bolts section.

Foliage damage from aphids, thrips, and some powdery mildew were the main detriments to the appearance of this yellow shrub rose. The plant was good at self-cleaning spent blossoms and maintained a mostly uniformly rounded habit with an occasional horizontal branch thrown out near the base of the plant. Flowering was high in late April to May, with the highest rebloom percentage averaging 50% coverage on the 50% ET_o treatment (Table 16a). Unfortunately, with low mid-season flowering rates, the foliage needed to carry the appearance of the shrub. After July, only the 50% irrigation treatment had acceptable average foliage ratings. With average flowering between 20 to 50% coverage, the plants on 50% of ET_o therefore averaged the best overall appearance ratings. There were no significant differences in growth between treatments.

This was one of the most discussed roses in the comment forms in the spring Open House event. Many listed this as their favorite plant, with some ascribing it the title “Best rose in the field.” The flowers, both their initial yellow color (“love the bright yellow!”) and their “change from yellow to white” were positively received by participants. Also noted was their scent and perceived “pollinator friend[liness]” due to the open, single nature of the flower. While scores did decline in subsequent open houses, this could be due to the bloom pattern of the cultivar (Table 16b). This cultivar put on a spectacular show with its initial bloom, then transitioned to a more subdued blooming pattern, always retaining a few flowers on the plant rather than cycling in and out of bloom in a boom and bust fashion. Overall, many continued to list this cultivar as their favorite plant and one they would recommend. One participant perfectly summed up the zeitgeist of Sunny Knock Out with the comment: “I am not a rose person, but this was lovely.”