Dr. Kirsten D. Hannam

Increased frequency and severity of heat waves and drought are becoming a major challenge for Okanagan fruit growers. These events can reduce fruit quality and compromise tree health, and may be an important trigger for sudden apple decline. A toolbox to help fruit growers mitigate the impacts of heat- and drought-related stress on fruit quality and tree health is urgently needed. Sprayable nanoparticle calcium carbonate is a potential tool for protecting fruit from sunburn and mitigating water stress, and is less expensive than shade cloth and/or evaporative cooling. This tool was tested on an experimental apple block at the Summerland Research and Development Centre over the summer of 2021. An initial spray was applied to test trees in early June, with a second spray applied immediately prior to the ‘heat dome’ event in late June, and a third spray in late July. Throughout the growing season, stem water potential, leaf transpiration and photosynthesis rates were monitored. At harvest, yield and fruit quality were assessed (e.g., sun burn [Schrader-McPherson scale], fruit size and weight, titratable acidity, and Brix. The calcium carbonate spray reduced the incidence of severe sun burn, but caused no other significant differences in fruit quality. When drought stress was applied, by temporarily cutting off the irrigation supply to both treatments, sprayed trees showed lower water stress than un-sprayed trees. Although just a preliminary study, this work suggests that sprayable protectants, such as nanoparticle calcium carbonate sprays, have potential for protecting fruit quality and mitigating drought stress during extreme heat or drought and may be an important, low-cost tool to include in Okanagan fruit growers’ climate change toolbox.

Bamber, N., Jones, M., Nelson, L., Hannam, K., Nichol, C., Pelletier, N. (2021). Life cycle assessment of mulch use on Okanagan apple orchards: Part 2 - Consequential. Journal of Cleaner Production, [online] 280 http://dx.doi.org/10.1016/j.jclepro.2020.125022

Midwood, A.J., Hannam, K.D., Forge, T.A., Neilsen, D., Emde, D., Jones, M.D. (2020). Importance of drive-row vegetation for soil carbon storage in woody perennial crops: A regional study. Geoderma, [online] 377 http://dx.doi.org/10.1016/j.geoderma.2020.114591

MacDonald JL, Forge T, Hannam K, Judd G, Moffat C, O'Gorman D, Sanfacon H, Xu H. 2020. 'Apple Decline' in the Okanagan Valley. Summerland Research and Development Centre via Instagram and Facebook.

Forge, T., Hannam, K., Neilsen, D., Neilsen, G. (2019). Nitrogen inputs and irrigation frequency influence population dynamics of Mesocriconema xenoplax under grapevines. Journal of Nematology, [online] 51(1), http://dx.doi.org/10.21307/jofnem-2019-084

Thomas, B.W., Hunt, D., Bittman, S., Hannam, K.D., Messiga, A.J., Haak, D., Sharifi, M., Hao, X. (2019). Soil health indicators after 21 yr of no-tillage in South Coastal British Columbia. Canadian Journal of Soil Science, [online] 99(2), 222-225. http://dx.doi.org/10.1139/cjss-2018-0146

Fentabil, M.M., Nichol, C.F., Jones, M.D., Neilsen, G.H., Neilsen, D., Hannam, K.D. (2016). Effect of drip irrigation frequency, nitrogen rate and mulching on nitrous oxide emissions in a semi-arid climate: An assessment across two years in an apple orchard. Agriculture, Ecosystems and Environment, [online] 235 242-252. http://dx.doi.org/10.1016/j.agee.2016.09.033

Hannam, K.D., Neilsen, G.H., Forge, T.A., Neilsen, D., Losso, I., Jones, M.D., Nichol, C., Fentabil, M.M. (2016). Irrigation practices, nutrient applications, and mulches affect soil nutrient dynamics in a young merlot (Vitis vinifera L.) vineyard. Canadian Journal of Soil Science, [online] 96(1), 23-36. http://dx.doi.org/10.1139/cjss-2014-0118

Hannam, K.D., Neilsen, G.H., Neilsen, D., Midwood, A.J., Millard, P., Zhang, Z., Thornton, B., Steinke, D. (2016). Amino acid composition of grape (Vitis vinifera L.) juice in response to applications of urea to the soil or foliage. American Journal of Enology and Viticulture, [online] 67(1), 47-55. http://dx.doi.org/10.5344/ajev.2015.15015