Sugar Bush

Rhus ovata

Rhus ovata in September 2015 on 20% of ET0. Photo: SK Reid.

Summary

Sugar bush is a Southern California native evergreen shrub that had mortality issues during the establishment phase of our trial, losing 2-3 plants on each treatment before the irrigation period in 2015. The 80% of ETo treatment lost an additional plant in May 2015 and one in October, and the 20% ETo treatment lost an additional plant in each of September and October for a final count of only 2 - 4 plants on each treatment, with only the 60% treatment retaining 4 plants. ANOVA and Tukey’s HSD revealed significance only in October’s relative plant growth index between treatments 80% and 20% at p ≤ 0.5, and between 40% and 20% at p≤ 0.1, although with the small remaining sample size, we do not have a high level of confidence in this conclusion. Overall average size at the end of the trial revealed the largest plants on the lowest treatments. Quality ratings were unequivocally higher on the two lower levels of irrigation (Table 9), but overall appearance was decidedly non-uniform making this plant most suitable to informal garden settings. Given the high rate of mortality for this species both before and during the trial period, it may not be advisable to plant it in soils as heavy as the silty clay loam of the current trials location. It may be beneficial to investigate comparative mortality in different soil types and with different irrigation regimens; we would have done so this year had we been able to locate plants in sufficient quantity to include them in a trial designed to determine that.

Growth and Quality Data

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Rhus ovata on 20% ET0 dying suddenly in September 2015. Photo: SK Reid.