Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Plant Science

First Advisor

W.E. Arnold


Preplant and preemergence herbicides are used currently to control broadleaf weeds in sunflowers (Helianthus annuus L.). These herbicides require incorporation practices or early rainfall to be effective and are most effective for control of grassy weeds but do not control certain broadleaf weed species. Broadleaf weeds such as wild mustard (Sinapsis arvensis L.) and redroot pigweed (Amaranthus retroflexus L.) are common in sunflower fields. Postemergence herbicides that control these broadleaf weeds are needed in sunflowers. Phytotoxicity of foliar-applied herbicides is often influenced by rainfall. The effect of rainfall on herbicide performance can be influenced by weed species, types and rates of herbicides, quantity of rainfall, and timing of rainfall. The purpose of this research was to evaluate the postemergence herbicides desmedipham [methyl m-hydroxycarbanilate carbanilate (ester)] and phenmedipham (methyl m-hydroxycarbanilate m-methylcarbanilate) for broadleaf weed control in sunflowers and to determine their performance under various rainfall conditions. The objectives for this research were to: 1) determine if tank mixtures of desrnedipham and phenrnedipham are synergistic for control of broadleaf weeds and if these mixtures can be safely used for weed control in sunflowers. 2) evaluate how rainfall quantity and rainfall timing affect the performance of desmedipham and phenrnedipham tank mixtures. 3) determine if different soil moisture levels affect the performance of desmedipham and phenmedipham tank mixtures. 4) determine if tank mixtures of sethoxydim and desmedipham plus phenmedipham can be used without loss in activity for broad spectrum grass and broadleaf weed control.

Library of Congress Subject Headings

Sunflowers -- Weed control
Sunflowers -- Weed control -- South Dakota



Number of Pages



South Dakota State University


No Copyright - United State