In North Carolina, the shoots of naturally-established, field grown, foliated specimens of turkey oak (Quercus laevis Walt.) and red maple (Acer rubrum L.) were treated in August with aqueous dilutions of three herbicidal products at three rates each. Simulated rainfall was applied at ½ or 1 inch at 5, 15, 60, or 120 min after herbicidal application. Responses measured 10 and 13 months after herbicidal application were percent control of original shoots, percent control of new shoots, shoot height, and number of live stems/plant. Neither the ester nor amine derivatives of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) were reduced as to their action on woody plants by the simulated rainfall applied. The action on woody plants of 4-amino-3,5,6-trichloropicolinic acid (picloram) plus 2,4-dichlorophenoxyacetic acid (2,4-D) was markedly reduced by the application of all of the simulated rain treatments at any of the intervals at which they were applied following herbicidal treatment.

Naturally-established individual specimens of 12 woody plant species occurring in North Carolina were treated with foliar, dormant stem, and basal applications of the propylene glycol butyl ether ester formulation of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), the propylene glycol butyl ether ester of 2,4-dichlorophenoxyacetic acid (2,4-D), and the potassium salt of 4-amino-3,5,6-trichloropicolinic acid (picloram). The triethanolamine salt of 2,4,5-T also was applied as a foliar treatment. Three rates of each herbicide were used. Responses measured were percent control of original shoots, percent regrowth, shoot height, and number of live stems per plant. No differences were observed between the amine and ester formulations of 2,4,5-T applied as foliar sprays except on rhododendron (Rhododendron maximum L.) where the ester produced 86% control compared to 28% for the amine salt. Foliar sprays of picloram were effective in controlling all species except white ash (Fraxinus americana L.), sweet gum (Liquidambar styraciflua L.), sweet bay (Magnolia virginiana L.), and rhododendron. Control of these species averaged only 45% compared to 96% on all other species studied. No species was effectively controlled by dormant stem or basal applications of picloram. All species considered, the propylene glycol butyl ether ester of 2,4,5-T applied as a dormant stem or basal application provided the most consistent results, giving 89% and 91% control, respectively.

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.