Investigation of physiological and molecular mechanisms conferring diurnal variation in auxinic herbicide efficacy.

The efficacy of auxinic herbicides, a valuable weed control tool for growers worldwide, has been shown to vary with the time of day in which applications are made. However, little is known about the mechanisms causing this phenomenon. Investigating the differential in planta behavior of these herbicides across different times of application may grant an ability to advise which properties of auxinic herbicides are desirable when applications must be made around the clock.

Adsorption, desorption and persistence of fomesafen in soil.

Background: Fomesafen provides control of glyphosate-resistant Palmer amaranth in cotton but frequent seedling injury has been reported. This study evaluated soil adsorption, desorption, and field persistence of fomesafen.

Results: The Freundlich distribution coefficient (K ) for fomesafen on seven US soils varied from 1.

Gene amplification confers glyphosate resistance in Amaranthus palmeri.

The herbicide glyphosate became widely used in the United States and other parts of the world after the commercialization of glyphosate-resistant crops. These crops have constitutive overexpression of a glyphosate-insensitive form of the herbicide target site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Increased use of glyphosate over multiple years imposes selective genetic pressure on weed populations.

Functional classification, genomic organization, putatively cis-acting regulatory elements, and relationship to quantitative trait loci, of sorghum genes with rhizome-enriched expression.

Rhizomes are organs of fundamental importance to plant competitiveness and invasiveness. We have identified genes expressed at substantially higher levels in rhizomes than other plant parts, and explored their functional categorization, genomic organization, regulatory motifs, and association with quantitative trait loci (QTLs) conferring rhizomatousness. The finding that genes with rhizome-enriched expression are distributed across a wide range of functional categories suggests some degree of specialization of individual members of many gene families in rhizomatous plants.

Sorption and desorption of flumioxazin to soil, clay minerals and ion-exchange resin.

Flumioxazin adsorption kinetics were described using a Greenville sandy clay loam soil. Adsorption kinetics experiments showed that 72% of total herbicide was absorbed after 1 h of continuous shaking and continued to increase to 78% after 72 h. Flumioxazin adsorption was then tested on seven agriculturally important soils throughout the southern USA.

Gas chromatographic/mass spectrometric determination of flumioxazin extracted from soil and water.

A method was developed for determining flumioxazin in soil and water. Recovery efficiencies for solid-phase extraction (SPE) of flumioxazin from deionized, well, and surface water were between 72 and 77%. SPE was superior to liquid-liquid extraction, using water-hexane and water-chloroform emulsions, which resulted in retrieval efficiencies of 25 and 22%, respectively.

Flumioxazin soil persistence and mineralization in laboratory experiments.

Flumioxazin is an herbicide registered for use in soybean and peanut. However, few published papers concerning the soil persistence of flumioxazin are available. Therefore, laboratory studies were initiated to determine the half-life (t(1/2)) of flumioxazin in Greenville sandy clay loam and Tifton loamy sand soils when incubated at 15 and 25 degrees C.