©2023 International Society of Arboriculture Arboriculture & Urban Forestry 49(5): September 2023 223 pigment change (e.g., B. sempervirens or intergeneric hybrid selections) in part shade to shade could reduce this overwintering phenomenon and should be incor- porated into design plans where evergreen function over the winter is desired or winter bronzing is unacceptable. Fertilization to Prevent Color Change Supplemental fertilization had no impact on the degree of winter color change in B. sempervirens ‘American,’ B. sempervirens ‘Rotundifolia,’ or B. microphylla ‘Winter Gem’ (Figure 3). In our experiment, the non- fertilized boxwoods were growing in soil with ade- quate nutrients, and supplemental fertilization did not impact color change. Fertilization may help reduce winter color change if plants are deficient; however, if nutrient supply is adequate, additional input will not have any effect. Thus, as stated in the ANSI-A300 standards for soil management, nutrient analysis should be conducted prior to application of fertilizer products (TCIA 2018). Although this controlled fer- tilization experiment was not replicated, we suspect that supplemental fertilization prior to wintertime will not reduce the winter color change of foliage. CONCLUSIONS Under favorable growing conditions, winter color change in boxwoods is a normal physiological phe- nomenon related to temperature, sun exposure, and species/cultivar, and is unaffected by additional nutri- ent input. When plants experience nutrient deficien- cies, pigment shifts do occur and should be addressed only after accurate diagnosis of the underlying cause(s), which may be related to soil factors such as nutrient content, pH, moisture availability, compac- tion, or root health. Before additional nutrients are applied, suspected nutrient deficiencies based on foli- age color should be validated by soil or tissue testing for nutrient content and other potential causal factors. The goal of any landscape professional should be to maintain ecological and aesthetic function of the managed landscape in the most environmentally sus- tainable manner possible. When plant “problems” arise, misdiagnosis or treatment without diagnosis of the underlying cause(s) leads to inappropriate chemi- cal input. Understanding the underlying mechanism and species/cultivar variability of a common aes- thetic concern in Buxus selections, the most common evergreen shrub in North America, is an important step in practicing sustainable landscape management. Furthermore, the sun exposure within a location of a landscape can significantly impact the winter color change and should be considered when boxwood are installed in a garden. LITERATURE CITED Batdorf LR. 2005. Boxwood handbook: A practical guide to knowing and growing boxwood. 3rd Ed. Boyce (VA, USA): American Boxwood Society. 123 p. Daughtrey ML. 2019. Boxwood blight: Threat to ornamentals. Annual Review of Phytopathology. 57:189-209. https://doi .org/10.1146/annurev-phyto-082718-100156 García-Plazaola JI, Esteban R, Hormaetxe K, Becerril JM. 2008. Seasonal reversibility of acclimation to irradiance in leaves of common box (Buxus sempervirens L.) in a deciduous forest. Flora: Morphology, Distribution, Functional Ecology of Plants. 203(3):254-260. https://doi.org/10.1016/j.flora.2007 .03.007 García-Plazaola JI, Hernández A, Becerril JM. 2000. Photopro- tective responses to winter stress in evergreen Mediterranean ecosystems. Plant Biology. 2(5):530-535. https://doi.org/10 .1055/s-2000-7469 Hall CR, Hong C, Gouker FE, Daughtrey M. 2021. Analyzing the structural shifts in U.S. boxwood production due to boxwood blight. Journal of Environmental Horticulture. 39(3):91-99. https://doi.org/10.24266/0738-2898-39.3.91 Hawke RG. 1994. Plant evaluation notes: Boxwoods for north- ern Midwest landscapes. Chicago Botanic Garden. 6:1-4. https://www.chicagobotanic.org/downloads/planteval_notes/ no6_boxwood.pdf Hormaetxe K, Becerril JM, Hernández A, Esteban R, García- Plazaola JI. 2007. Plasticity of photoprotective mechanisms of Buxus sempervirens L. leaves in response to extreme tem- peratures. Plant Biology. 9(1):59-68. https://doi.org/10.1055/ s-2006-924456 Hormaetxe K, Hernández A, Becerril JM, García-Plazaola JI. 2004. Role of red carotenoids in photoprotection during win- ter acclimation in Buxus sempervirens leaves. Plant Biology. 6(3):325-332. https://doi.org/10.1055/s-2004-817883 Kogan M. 1998. Integrated pest management: Historical per- spectives and contemporary developments. Annual Review of Entomology. 43:243-270. https://doi.org/10.1146/annurev .ento.43.1.243 Le Duc A, Parsons LR, Pair JC. 2000. Growth, survival, and aesthetic quality of boxwood cultivars as affected by land- scape exposure. HortScience. 35(2):205-208. https://doi.org/ 10.21273/HORTSCI.35.2.205 Muñoz P, Cotado A, Munné-Bosch S. 2021. Transient photoin- hibition and photo-oxidative stress as an integral part of stress acclimation and plant development in a dioecious tree adapted to Mediterranean ecosystems. Tree Physiology. 41(7):1212-1229. https://doi.org/10.1093/treephys/tpaa177 Saunders Brothers. 2018. Boxwood guide. 5th Ed. Piney River (VA, USA): Saunders Brothers Nursery. 98 p. https://www. saundersbrothers.com/_ccLib/attachments/pages/Boxwood +Guide+copy.pdf TCIA. 2018. ANSI A300 (Part 2)—2018 Soil Management. Lon- donderry (NH, USA): Tree Care Industry Association. 20 p.
September 2023
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
