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.

17-β estradiol and testosterone mineralization and incorporation into organic matter in broiler litter-amended soils.

The presence of the hormones estradiol and testosterone in the environment is of concern because they adversely affect vertebrate sexual characteristics. Land spreading broiler litter introduces these hormones into the environment. We conducted two studies.

17β-estradiol and testosterone sorption in soil with and without poultry litter.

17β-estradiol and testosterone are naturally occurring steroids that co-occur in poultry litter. The effects of litter on sorption of these hormones to soil are not known. Sorption isotherms were developed for C-labeled testosterone and H-labeled estradiol in a Cecil sandy clay loam with and without poultry litter addition.

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.