Stand dynamics of an old-field longleaf pine stand following herbicide application, poor survival, and subsequent replantingThis article is part of a larger document. View the larger document here.
A study area in Emanuel County, GA installed to discern the effectiveness of various herbicides over newly planted (December 1999) longleaf pine (Pinus palustris Mill.) seedlings on an old-field site. Survival and height growth data after herbicide treatment indicate that the early (April 7, 2000) Oust+Velpar L herbicide treatment gave greater initial survival and height growth compared to nine later herbicide treatments (May 9, 2000) or an untreated control. First year survival ranged from 90 percent with the April Oust+Velpar L treatment to 40 to 63 percent with the May herbicide treatments. All dead seedlings spots that were flagged and numbered were replanted in December 2000 in the May treatments and control plots. After six growing seasons, mean longleaf survival, d.b.h., height, and green weight per acre were greater with the April application. Sixth year survival ranged from 79 percent in the April application, 53 to 67 percent for the May herbicide treatments, and 41 percent for the control. In the May treatments, originally planted trees had significantly larger heights and diameters than the replanted trees. Original planted trees had an average diameter of 3.4 inches and height of 16 feet. Replanted trees had an average diameter of 1.9 inches and height of 9 feet. During the spring of 2000, rainfall patterns were well below normal. It appears that the early April herbicide treatment allowed for the seedlings to survive this critical dry period. These results indicate that substantial longleaf establishment costs can be saved with an earlier herbicide application under severe spring drought conditions on upland well drained soils.