Forest Site Conversion with Soil Applied Herbicides

On low-quality hardwood sites, treated with nonliquid herbicides, the mean first-year survival of combined red and white pine seedlings was 84 percent, compared to a 96 percent survival on untreated sites. Of four chemicals, applied to the soil by broadcast and individual stem methods, 25 percent active fenuron and 22 percent active fenuron TCA, killed such overstory species as white, chestnut and red oaks, and red maple. Picloram pellets (10 percent active), applied by similar methods, were most effective in killing understory witch hazel, sassafras, and hickory. The fourth herbicide, a 10 percent active dicamba granule applied at the same rates, was ineffective in killing undesirable, hardwoods. A light, prescribed surface fire, carried out in advance of herbicide application, killed most stems three inches or less in diameter, but did not improve the kill on larger stems through increased chemical absorption by removal of the surface litter.