Acclimation and Low-temperature Tolerance of Eight Woody Taxa

Timing and rate of acclimation and maximum low-temperature survival of eight woody taxa were determined over six sample dates from 25 Aug. 1987 to 25 Apr. 1988. Four cultivars of Acer rubrum L. (red maple) acclimated at different rates and attained different levels of midwinter cold hardiness. ‘Red Sunset’ (RS) and ‘October Glory’ (OG), northern selections, acclimated at faster rates and attained greater degrees of cold hardiness than ‘Journalism Psychology’ (JP) and ‘Upright Crown’ (UC) selected from southern seed sources. Maximum cold hardiness levels were −8C (JP), −23C (UC), −29C (RS), and −29C (OG). Amelanchier arborea (Michx. f.) Fern, (downy serviceberry) and Quercus coccinea Muenchh. (scarlet oak) developed midwinter hardiness of less than −29C and −20C, respectively. Illicium floridanum Ellis (Florida anise) and Illicium parviflorum Michx. (small anise) developed −26C and −20C midwinter hardiness, respectively. According to our data, woody taxa should be evaluated for timing and rates of acclimation and low-temperature tolerances, since performance will vary from one geographic area to another, depending on photoperiod, the timing of fall freezes, and midwinter temperatures.