Compensation by resprouts of clipped Amur honeysuckle (Lonicera maackii, Caprifoliaceae) shrubs to honeysuckle leaf blight and deer browsing1

Amur honeysuckle (Lonicera maackii) is a highly invasive shrub that is difficult to control. Although clipping by itself is ineffective, previous work has shown that it produces resprouts that are highly susceptible to honeysuckle leaf blight (Insolibasidium deformans), which kills leaves that it infects. Additionally, resprouts are also browsed by white-tailed deer (Odocoileus virginianus). One purpose of this study was to estimate blight impact on resprouts by quantifying the fraction of leaves lost during the growing season that are blighted, thereby quantifying blight's effect on growth. Another purpose was to quantify the effect of deer browsing on the growth of clipped shrubs and to look for an interaction between leaf blight and deer browsing. Shrubs were clipped in a forested site and an open site in northern Kentucky, and half of them were protected by deer exclosures. Growth of resprouts was measured on a biweekly basis. Repeated-measures analyses showed that the fraction of leaves lost to blight had no effect on growth at either site. Deer browsing also had no effect, and there was no interaction between blight and browsing. Thus, resprouts were able to compensate for losses from leaf blight and deer browsing during the growing season. Shrub mortality rates 1 yr after clipping were similar to those reported before leaf blight and extensive deer browsing were reported. However, shrub mortality rates of open-grown shrubs that were both clipped and reclipped the following year were much higher than previously seen. Thus, the combination of blight and deer browsing with reclipping shows some promise for now managing honeysuckle in open-grown stands.