Response of Turkey Oak to 2,4,5-T as a Function of Final Formulation Oil Content

Abstract

Shoots of naturally established specimens of turkey oak (Quercus laevis Walt.) 3 to 6 ft high were treated with 4 to 8 lb aehg of a commercial concentrate formulation of the butoxyethanol ester of (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) on or about May 1, June 1, July 1, August 1, and September 1. Foliar applications were made to the point of run-off and foliar-basal treatments were made first to the basal 8 inches of the main stem and then to the lower four-fifths of the remainder of the shoot. The objective was to assess the utility of number two diesel fuel as an additive for such treatments when the oil was used at rates of 0, 5, 10, and 20% in the final formulations. The experiment was repeated in 3 different years. Responses measured approximately 11, 14, and 23 months after initial treatment were percent control of original shoots, percent control of new shoots, shoot height, and number of live stems/plant. Foliar treatments without oil were progressively less effective as they were made later in the growing season. The addition of oil to foliar treatments provided more effective control of the original shoots and greater reduction in shoot heights, especially when the oil concentration was 20%. The foliar-basal method was notably ineffective in the absence of oil. Addition of oil to the foliar-basal treatments provided marked improvement in the original shoot, total shoot control index, shoot height, and stems/plant responses, especially at the 20% level of oil. Diesel fuel is useful as an additive for 2,4,5-T sprays to be applied to turkey oak, especially where treatment is to be made in the latter half of the growing season and in particular where the lower stems can be treated.