Translocation and Fate of Dicamba, Picloram, and Triclopyr in Horsenettle,Solanum carolinense

Abstract

Greenhouse studies were conducted to determine the extent of translocation from the foliage to fleshy roots, the inherent toxicity, and the fate of radiolabeled and nonlabeled dicamba, picloram, and triclopyr in horsenettle. Roots of horsenettle acted as the major sink for photosynthate accumulation at the 0.2- to 0.5-bloom growth stages as determined by autoradiography. Dicamba, picloram, and triclopyr were translocated into the roots of horsenettle and accumulation continued for at least 16 days.14C associated with each herbicide found in the roots ranged from 1.3% at 4 days to 3.8% at 16 days. After 16 days, slightly more14C from plants treated with dicamba and triclopyr (3.8 and 3.6%) than picloram (3.0%) was translocated to roots. These compounds were metabolized slowly in the foliage and roots as determined by thin-layer chromatography (TLC) and autoradiography. In translocation studies with horsenettle shoots, picloram at 1.12 kg/ha killed the treated and untreated shoots and roots. Dicamba and triclopyr at the highest rates killed the treated shoots and partially destroyed the root system. Symptoms were noted on the untreated shoots, but full recovery occurred at 8 weeks. Since each of the herbicides was metabolized slowly and only slight differences in their translocation were observed, the relatively higher herbicidal effectiveness of picloram must be attributed to its greater inherent potency.

Absorption, Translocation, and Metabolism of Picloram and 2,4-D in Leafy Spurge (Euphorbia esula)

“…Previous research has shown picloram and 2,4-D conjugates remain stable at least 3 to 4 months when frozen. 5 Herbicides and metabolites were extracted by grinding in 80% ethanol:water (v/v) in a motor-driven tissue homogenizer, followed by centrifugation and re-extraction of the pellet twice in the same solvent mixture to increase recovery. The extracts were combined and extracted with ether once.…”

Horsenettle (Solanum carolinense L.) plants emerged at different times after corn (Zea mays L.) planting

“…The efficacy of control of horsenettle depends on the ability to control the vigorous root system of the plant (Gorrell et al . 1988).…”

Root system architecture and its relationship to the vegetative reproduction function in horsenettle (Solanum carolinense)

“…Generally, effective translocated herbicides for horsenettle root systems are auxin‐based (e.g. triclopyr) (Gorrell et al . 1978, 1988).…”

“…Generally, effective translocated herbicides for horsenettle root systems are auxin-based (e.g. triclopyr) (Gorrell et al 1978(Gorrell et al , 1988. Therefore, the elucidation of the endogenous morphological control of the root system in relation to auxin is important, both to improve weed control efficacy and to solve general physiological questions regarding root development.…”