Joseph H. Massey

Effect of Adjuvant and Urea Ammonium Nitrate on Bispyribac Efficacy, Absorption, and Translocation in Barnyardgrass (Echinochloa crus-galli). II. Absorption and Translocation

Abstract Inconsistent control of barnyardgrass with bispyribac may be alleviated through adjuvant technology. Experiments were conducted to determine the effect of adjuvant and urea ammonium nitrate (UAN) on absorption and translocation of bispyribac in barnyardgrass. Additional experiments were conducted to determine when maximum absorption and translocation occurred with the use of a methylated seed oil/organosilicone adjuvant (MSO/OSL) plus UAN (0.37 L ha−1 and 2% v/v). In the initial experiment, 14C-bispyribac–treated leaves, nontreated leaves, and roots were collected 6 and 24 h after application. Absorption was greatest with tank-mixed MSO/OSL (0.37 L ha−1) plus UAN (2% v/v) and the proprietary blend of MSO/OSL/UAN (2% v/v) at 80 and 74% of applied 14C-bispyribac, respectively. Translocation to nontreated leaves and roots was also highest with these treatments. Increased translocation appeared to be due to greater herbicide absorption, not an increase in translocation rate. The addition of 32% UAN to MSO/OSL and nonionic organosilicone (OSL/NIS) adjuvant systems resulted in a four to fivefold increase in absorption compared with treatments without UAN. Recovery of 14C-bispyribac in additional experiments generally decreased as time after application increased; however, recovery was 86% or greater for all time intervals. By 12 h after application, 68% of applied 14C-bispyribac was absorbed. At this time, 14C-bispyribac was partitioned within the plant in the following manner: 48% in the treated area, 10% in leaf tissue from treated area to tip of the treated leaf, 1.9% in leaf tissue from treated area to collar region of the treated leaf, 1.6% in remaining leaves from collar of treated leaf upward, 5.3% in remaining leaves from collar of treated leaf downward to soil line, and 0.7% in the roots. These data indicate that maximum absorption was achieved within 12 h with a tank mix of MSO/OSL and UAN or the MSO/OSL/UAN blend. Nomenclature: Bispyribac; barnyardgrass, Echinochloa crus-galli (L.) Beauv. ECHCG

Identification of the Inositol Isomers Present in Tetrahymena

Abstract The inositol isomer composition of phosphoinositides, polyphosphoinositols, phosphatidylinositol-linked glycans, and glycosyl phosphatidylinositol-anchored proteins of logarithmic phase Tetrahymena vorax was determined by GC-MS analysis of trimethylsilylimadazole derivatives. The most abundant inositol found was the myo-isomer; however, appreciable percentages of scyllo-inositol were present in the free inositol pool, phosphatidylinositol-linked glycan fraction, and glycosyl phosphatidylinositol-anchored protein fraction. Trace quantities of chiro- and neo-inositols also were present.

Fluometuron adsorption to vegetative filter strip components

Abstract Research on best management practices, including vegetative filter strips, is needed to evaluate the potential for reducing herbicides in surface runoff. Laboratory studies were conducted to determine the influence of different filter strip components on fluometuron adsorption. Samples were taken from a switchgrass filter strip (1-m wide) established on a Brooksville silty clay. Sampled components included switchgrass stems clipped to 4 cm, plant residue on the soil surface, and topsoil < 5-mm, 0.5- to 1-cm, 1- to 3-cm, and 3- to 5-cm deep. The filter strip topsoil samples contained 1.8, 2.2, 2.3, and 2.8% organic matter for the aforementioned depths, respectively, compared with 1.8% in soil collected from an adjacent cropped area. Fluometuron adsorption on each sample was compared at initial concentrations of 0.017, 0.5, 1.0, 2.0, and 4.0 mg L−1, the last of these representing four times the peak concentration in surface runoff. Fluometuron adsorption was greater in soil from filter strip areas than in soil from cropped areas. Averaged over concentration, the soil–water partition coefficient (Kd) value for soil 1- to 3-cm and 3- to 5-cm deep was greater than the value for soil from the cropped area. Stems and residue had Kd values 4.9- and 4.1-fold greater, respectively, than soil from the cropped area. Average adsorption coefficients normalized for organic carbon content (Koc) of soil < 5-mm and 3- to 5-cm deep from filter strip areas were greater than the values for soil from cropped areas. Nomenclature: Fluometuron; switchgrass, Panicum virgatum L.

Environmental fate of S-Metolachlor: a review

S-metolachlor is a preemergent herbicide used for the control of annual grasses and small-seeded broadleaf weeds in more than 70 agricultural crops worldwide. Recently, Smetolachlor has been used to control imidazolinone-resistant red rice in rice-soybean rotation in lowland environments of the Southern Brazil. However, limited information concerning the environmental fate of S-metolachlor in lowland soil is available in the literature. Thus, this review was designed to describe the major transport and dissipation processes of Smetolachlor in attempting to improve weed management programs used in rice-soybean rotation and mitigate environmental contamination of lowland areas.

Iron antagonism of MSMA herbicide applied to bermudagrass: characterization of the Fe2+-MAA complexation reaction

Abstract Discoloration of bermudagrass often results from application of MSMA herbicide used to control southern crabgrass and other weeds. However, when products containing iron sulfate (FeSO4) are tank-mixed with MSMA, this discoloration is reduced. Experiments investigated the effect of tank-mixing organic arsenical herbicides with FeSO4 or a chelated iron source (Sprint 330) in terms of southern crabgrass control and injury to bermudagrass. Tank-mixing MSMA with FeSO4 reduced bermudagrass injury. However, southern crabgrass control was also reduced by at least 50% with the addition of ≥0.38 kg Fe2+ ha−1. Neither antagonism nor safening of bermudagrass was observed when the chelated Fe2+ source was used. Applying FeSO4 as a separate treatment 1 to 4 d before or after MSMA application did not reduce visual burmudagrass injury 1 wk after treatment. Solution pH and FeSO4 concentration controlled the extent of complexation and level of antagonism observed in the field; inorganic Fe2+ reacted with MSMA to form a complex having reduced herbicidal activity. Potentiometric and spectrophotometric investigations found that methylarsonate, the parent acid of MSMA and other organic arsenical herbicides, reacts with inorganic Fe2+ to form a stable 1:1 Fe2+-methylarsonic acid chelate having two points of metal coordination and a stability constant log10 (β) = 2.77 ± 0.04. Tank-mixing MSMA with FeSO4 to protect against bermudagrass injury negates the benefit of applying the herbicide for weed control, and therefore is not a recommendable practice for turf managers. Nomenclature: MSMA; common bermudagrass, Cynodon dactylon (L.) Pers.; southern crabgrass, Digitaria sanguinalis (L.) Scop. DIGSP.

Dissipation of Clomazone, Imazapyr, and Imazapic Herbicides in Paddy Water under Two Rice Flood Management Regimes

Information on the dissipation of clomazone, imazapyr, and imazapic in paddy water under different irrigation system is not available in the literature. The objective of this study was to investigate the effect of two irrigation systems (intermittent (IF) and continuous (CF) flood) on the dissipation of clomazone, imazapyr, and imazapic in paddy water. Imazapic was the least persistent herbicide in paddy water, with DT50-values of approximately 3 and 5 d under CF and IF, respectively. Imazapyr required a two-fold increase in time to reach its half-life in water in contrast to imazapic, with DT50-values of approximately 6 and 11 d under CF and IF, respectively. Clomazone showed the highest DT50-values, varying between 7 to 21 d under CF and IF, respectively. Imazapyr and imazapic dissipation was faster under CF, while clomazone was not affected. This investigation found that the dissipation behaviors of herbicides vary under different rice irrigation regimes. Thus changes in irrigation management, as will be required to produce more rice grain with less water to avoid future scarcity, should consider impacts of flood management on herbicide persistence and environmental behavior. Nomenclature: Clomazone; mazapyr; imazapic; rice, Oryza sativa L.