Plant breeding programs primarily focus on improving a crop's environmental adaptability and biotic stress tolerance in order to increase yield. Crop improvements made since the 1950s – coupled with inexpensive agronomic inputs, such as fertilizers, pesticides, and water – have allowed agricultural production to keep pace with human population growth. Plant breeders, particularly those at public institutions, have an interest in reducing agriculture's negative impacts and improving the natural environment to provide or maintain ecosystem services (eg clean soil, water, and air; carbon sequestration), and in creating new agricultural paradigms (eg perennial polycultures). Here, we discuss recent developments in, as well as the goals of, plant breeding, and explain how these may be connected to the specific interests of ecologists and naturalists. Plant breeding can be a powerful tool to bring “harmony” between agriculture and the environment, but partnerships between plant breeders, ecologists, urban planners, and policy makers are needed to make this a reality.

Biological invasions have far reaching effects on native plant and arthropod communities. This study evaluated the effect of natural enemies on eggs of the exotic invasive brown marmorated stink bug Halyomorpha halys (Stål) in experimental plots comprising species pairs of 16 ornamental trees and shrub genera from either Eurasia or North America and in wooded areas adjacent to the plots. Sentinel egg masses were placed on leaves of Acer, Cercis, Hydrangea, and Prunus in the plots and in seven genera of trees and shrubs in adjacent woods. Overall, rates of parasitism and predation in experimental plots were low, accounting for only 3.6 % and 4.5% of egg mortality, respectively. There were no significant differences in parasitism and predation rates between native or exotic plots or between plants of different genera. In 2015, predation was significantly higher in the experimental plots than in the wooded sites, but parasitism was significantly higher in the wooded sites. In the experimental plots, seven native and one exotic parasitoid species attacked sentinel egg masses. Six native parasitoid species attacked sentinel egg masses in the wooded sites. Parasitoids in the genus Trissolcus were more likely to attack egg masses in exotic plots than in native plots. There is no evidence that native natural enemies attacking eggs of the exotic BMSB were more prevalent in landscapes with native ornamental trees and shrubs than those with exotic trees and shrubs.

Hemlock (Tsuga) species and hybrids were evaluated for resistance to the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). The adelgid was accidentally introduced from Asia to the eastern United States, where it is causing widespread mortality of the native hemlocks, Tsuga canadensis (L.) Carrière and Tsuga caroliniana Engelm. These two native species plus the Asian species Tsuga chinensis (Franch.) E. Pritz and T. dumosa (D.Don) Eichler and Tsuga sieboldii Carrière, and the hybrids T. chinensis x T. caroliniana and T. chinensis x T. sieboldii, were artificially infested with the crawler stage of A. tsugae in the early spring 2006 and 2007. After 8 or 9 wk-when the spring (progrediens) generation would be mature--counts were made of the adelgid. In both years, the density of A. tsugae was highest on T. canadensis, T. caroliniana, and T. sieboldii; lowest on T. chinensis; and intermediate on the hybrids. On T. chinensis and the T. chinensis hybrids, fewer adelgids settled, fewer of the settled adelgids survived, and the surviving adelgids grew slower. Thus, the nature of the host resistance is both nonpreference (antixenosis) and adverse effects on biology (antibiosis). Tree growth (height) was associated with resistance, but no association was found between time of budbreak and resistance that was independent of the taxa. Many of the hybrids grow well, have attractive form, and are promising as resistant landscape alternatives for the native hemlocks.

Accessions in the National Boxwood Collection of the U.S. National Arboretum were inoculated with Calonectria pseudonaviculata in order to determine susceptibility to boxwood blight as part of longer-term evaluations of whole plants. Terminal unrooted cuttings were inoculated with C. pseudonaviculata and symptoms rated. Cuttings showed a wide range in susceptibility. There were significant differences in percent diseased leaves and percent defoliation among the 42 species and cultivars. Cuttings of some Buxus sempervirens cultivars were among those with the highest percent diseased leaves, with eight cultivars showing as much disease as B. sempervirens ‘Suffruticosa’: ‘Scupi’, ‘Pendula’, ‘Rotundifolia’, ‘Denmark’, ‘Handsworthiensis’, ‘Northland’, ‘Arborescens’, and ‘Northern New York’. All others showed significantly less disease, as measured by percent diseased leaves. A number of accessions were contrasted to the less susceptible B. sinica var. insularis ‘Pincushion’ and showed a similarly low level of disease: Buxus ‘Green Ice’, B. sempervirens ‘Decussata’, B. sinica var. insularis ‘Wintergreen’, Buxus, sp. (57950*H), Buxus ‘Green Mound’, B. sinica var. insularis ‘Winter Beauty’, and B. microphylla var. japonica ‘Winter Gem’. A diverse array of germplasm is available in the genus Buxus, and identifying acceptable levels of disease tolerance in cultivars that represent this diversity will contribute to its continued use in ornamental landscapes. Accepted 25 December 2014. Published 26 January 2015.