Time of Pruning Effects on Cold Hardiness of Butterfly Bush

Abstract

A study was conducted over a two-year period to determine how time of pruning affects cold hardiness of butterfly bush (Buddleia davidii (Franchet) ‘Royal Red’). Plants were pruned in November, January, or March, and pruned and non-pruned plants were exposed to six freezing temperatures two weeks after pruning treatments were applied. In addition, plants pruned in previous seasons were included in subsequent freezing treatments. Plants were rated for injury 2 or 3 weeks after treatment (WAT), and for mortality at 6 WAT. In fall 2001, at −6C (21.2F), injury ratings were higher in pruned than non-pruned plants. At all other treatment temperatures, injury to pruned and non-pruned plants was similar. In fall 2001, mortality increased with decreasing temperatures and was higher in pruned plants than in non-pruned controls, regardless of treatment temperature. In winter and spring 2002, injury and mortality increased with decreasing temperatures, but were not affected by pruning treatments. In fall 2002, temperature decreased as injury rating and mortality increased, regardless of pruning treatment and pruned plants had a higher injury rating and mortality than non-pruned across all temperatures. In winter 2003, injury rating and mortality increased with decreasing temperatures and pruning did not affect either. Spring 2003 plants, which had deacclimated prior to freeze treatment, were not affected by pruning or freezing treatments.

Evaluation of 14 Butterfly Bush Taxa Grown in Western and Southern Florida: I. Visual Quality, Growth, and Development

“…The enormous ornamental value of butterfl y bush has warranted its use in numerous research programs addressing production practices or landscape uses such as cultivar sensitivity to acute ozone (Findley et al, 1997), growth regulation during container production (Keever and Gilliam, 1994), effects of spacing on cut fl ower production (Armitage and Dirr, 1995), effects of dolomitic lime on growth and nutrient uptake (Gillman et al, 1998), effects of pruning time on cold hardiness (Warr et al, 2002), susceptibility to twospotted spider mite (Tetranychus urticae) (Gillman et al, 1999), and susceptibility to root-knot nematodes (Thetford and Kinloch, 2002). Butterfl y bush is listed as one of 10 woody landscape plants commonly damaged by rootknot nematodes in Florida (Crow and Dunn, 2002) and recent work by Thetford and Kinlock (2002) identifi ed 12 butterfl y bush taxa susceptible to the root knot nematodes Meloidogyne arenaria and M. incognita.…”