Black spruce outplant performance: effect of winter application of hexazinone on shear-bladed sites in boreal Ontario

Abstract

Three field experiments were carried out to assess the performance of 1.5 + 1.5 black spruce (Piceamariana (Mill.) B.S.P.) transplants and FH508 Japanese paperpot seedlings in relation to various levels of chemical site preparation with Pronone® (granular hexazinone) applied during the winter to 4700 trees on shear-bladed, imperfectly drained stone-free clay and clay loam soils. Second- and 3rd-year assessments revealed that both stock types responded similarly to chemical site preparation. Growth data were fitted to linear and, where appropriate, quadratic response models. The response of planted seedlings was positive and generally linear over the range of dosages (0 to 6 kg active ingredient/ha) applied. Chemical site preparation had little or no effect on survival of either stock type. In comparison with the transplants, the paperpot seedlings were in better condition and were of a similar size at the end of the assessment period.