Birch Control on Lowland Heaths: Mechanical Control and the Application of Selective Herbicides by Foliar Spray

Publisher Website
Google Scholar
Abstract
Birch is a problem weed on many lowland health nature reserves. In order to devise control methods suitable for conservation use, an experiment was carried out to compare the effects of mechanical control methods, and foliar sprays of 3 selective herbicides (fosamine ammonium, 2,4,5-T and triclopyr) singly or in combination with cutting. The effect of these treatments on the target species (birch: Betula pendula Roth. and B. pubescens Ehrh.) was assessed as well as their effects on a non-target species (Calluna vulgaris). Particular attention was paid to damage and recovery of the Calluna population. Of the mechanical means of controlling birch, cutting was not as successful as the labor intensive and time-consuming pulling, primarily because birch regenerated from the cut stumps. Cutting in successive years increased the degree of control. Mechanical treatments did not adversely affect the Calluna understorey, and these treatments tended to increase the number of regenerating Calluna seedlings. All 3 herbicides, whether applied to birch scrub or to regrowth after cutting, gave better control than cutting treatments without herbicide application. Applying triclopyr, but not fosamine ammonium or 2,4,5-T, decreased the number of birch seedlings. Fosamine ammonium and 2,4,5-T damaged some, and killed a few Calluna plants, but recovery was rapid. Triclopyr on the other hand reduced the number of Calluna plants and seedlings. The role of selective herbicides for the control of birch by foliar spray for practical conservation purposes is discussed in relation to efficacy of birch kill, and damage to Calluna. On balance it appears that fosamine ammonium and 2,4,5-T are the most suitable herbicides for this purpose.