Pat Bowen,* Brad Estergaard, and Carl Bogdanoff 
*Agriculture and Agri-Food Canada, Summerland Research and Development Centre, 4200 Highway 97, Summerland, BC, V0H 1Z0, Canada (pat.bowen@agr.gc.ca)

Young grapevines are particularly prone to winter cold damage because of their small size and exposure to lethally cold air that pools on the vineyard floor. The effects of protective cover treatments on the temperature of young grapevine stems and roots was evaluated over two winters. In winter 2015 to 2016, the treatments were: empty and sawdust-filled 2-L cardboard cartons, mounded sawdust, foam insulation wrap, and no protection (control). The same treatments plus a mounded soil treatment were applied in winter 2016 to 2017. Treatment effects on vine temperatures were influenced by snow cover and ambient temperatures in the previous week. Averaged over the treatment period, daily minimum temperatures of vine stems and roots were similar for the unprotected (control) and empty-carton treatments and were up to 1°C warmer for the sawdust-filled carton, up to 5°C warmer for mounded sawdust or soil, and up to 1°C cooler for the pipe-insulation wrap. Snow cover further increased the minimum temperature of vines under sawdust mounds in 2015 to 2016. Compared with no protection, foam insulation wrap increased the daytime maximum temperature of vine stems by up to 6°C, but decreased the nighttime minimum temperatures by up to 4°C. The mounded sawdust and soil treatments were the most effective at increasing nighttime minimum temperatures of vine stems; however, in spring 2016, a high mortality rate was observed for buds that had been buried in sawdust.

Funding Support: BC Wine Grape Council and Agriculture and Agri-Food Canada