Screening Buddleia Cultivars for Acute Ozone Sensitivity

Abstract

Eight cultivars of buddleia were exposed to ozone (O3) concentrations up to 375 ppb for two 4-hour periods on consecutive days in 1995. Visible injury to all cultivars consisted of small, discrete spots, reddish purple in color, on the adaxial leaf surface. Cultivars differed in sensitivity to acute O3 exposure with ‘Empire Blue’ and ‘Opera’ being the most tolerant and ‘Black Knight’, ‘Nanho Blue’, ‘Pink Delight’, and ‘Royal Red’ the most sensitive. Severe injury occurred on the most sensitive cultivars with O3 exposures of 250 or 375 ppb. At the highest O3 concentration, the severity index (SI), an indicator of foliar injury, ranged from 1.3 (less injury) for ‘Opera’ to 4.6 (more injury) for ‘Pink Delight’. An exposure-response study with ‘Black Knight’ resulted in visible injury increasing as both concentration and number of exposures increased, with the most severe injury to plants given the most exposures (5 days) to the highest concentration (375 ppb, SI of 6.3).

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.…”