No abstract

Using a Cu(II) 2-quinoxalinol salen complex as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant, allylic activations of olefin substrates can be converted to the corresponding enones or 1,4-enediones. Excellent yields can be achieved (up to 99%) within a very short reaction time and with great tolerance for additional functional groups. Possible mechanistic pathways have been characterized using Raman spectroscopy, cyclic voltammetry, and theoretical calculations.

High pH soils frequently lead to iron deficiency chlorosis (IDC) in soybean [Glycine max (L.) Merr.]. As a result, yields for soybean are often reduced. Studies in the north-central United States have shown improvements in grain yield after applying Fe chelates on calcareous soils, but this practice has not been evaluated in a southern climate. Two sites within the Blackbelt region of Alabama were evaluated for response to Fe-EDDHA, Fe-Citrate, and FeSO 4 for their effect on yield and chlorosis in 2010, 2011, and 2012. Treatments were applied in-furrow at planting, as a foliar spray at the V3 growth stage, or as a split-application. Remote sensing, relative chlorophyll meter readings, and visual chlorosis scores (VCS) were assessed as methods for identifying degree of Fe chlorosis. At the location where IDC was most pronounced, all treatments of Fe-EDDHA were effective at reducing VCS ratings when applied in-furrow at planting; however, chlorosis evaluation through remote sensing and relative chlorophyll readings was not able to detect improvements in chlorosis measured with VCS. Treatments of Fe-EDDHA at 4.5 kg product ha -1 increased yield whether applied as an in-furrow at planting treatment or as a split application at planting and at V3 growth stage as a foliar spray. Treatments of Fe-Citrate and FeSO 4 did not improve yield as applied in this study. Results suggest that Fe-EDDHA can be used in southern climates as a strategy to overcome IDC yield limitations.

A frequently used cropping system in the southeastern Coastal Plain is an annual rotation of cotton (Gossypium hirsutum L.) and peanut (Arachis hypogaea L.) under conventional tillage (CT). The traditional peanut–cotton rotation (TR) often results in erosion and loss of soil organic carbon (SOC). Incorporation of bahiagrass (Paspalum notatum Fluegge) into the peanut–cotton rotation for 2 yr (also called a sod‐based rotation or SBR) has been suggested for improving SOC, particularly in conjunction with conservation tillage practices. To determine the effect of the SBR on carbon sequestration, SOC and its isotopic composition were evaluated on established (>10 yr) crop rotation systems. Cropping systems evaluated included (i) TR under CT, (ii) TR under strip tillage (ST), (iii) SBR under CT, (iv) SBR under ST, and (v) SBR under ST with cattle grazing. Total SOC, bahiagrass‐derived SOC, and potential C mineralization increased in the top 10 cm of soil, indicating the potential for ST to improve soil fertility in SBR systems. Grazing bahiagrass decreased SOC in the 5 to 10 cm depth, but this effect was not observed for the subsequent peanut crop and did not appear to have a long‐term negative effect on SOC storage. The SBR did not show consistent improvements in total SOC compared with the TR. A 3‐yr comparison of SOC concentration revealed C increases in SBR and TR systems, indicating that other conservation practices (e.g., winter cover cropping) are the primary contributors to SOC storage for Coastal Plain soils evaluated in this study. Isotopic analysis of mineralized CO2 indicated bahiagrass‐derived SOC may be preferred over C3 crop‐derived SOC for degradation.

Dithiopyr and dinitroanilines are preemergence-applied, mitotic-inhibiting herbicides used to control goosegrass [Eleusine indica (L.) Gaertn.]) in turfgrass. A suspected resistant E. indica population was collected from a golf course putting green and was evaluated for possible resistance to dithiopyr and prodiamine. After dose-response evaluation, the α-tubulin gene was sequenced for known target-site mutations that have been reported to confer resistance to mitotic-inhibiting herbicides. A mutation was discovered that resulted in an amino acid substitution at position 136 from leucine to phenylalanine (Leu136-Phe). Previous research has indicated that Leu136-Phe does confer resistance to dinitroaniline herbicides. The level of resistance indicated by regression models and I50 values indicates that there is a 54.1-, 4.7-, >100-, and >100-fold resistance to dithiopyr, prodiamine, pendimethalin, and oryzalin, respectively when compared to the susceptible population based on seedling emergence response and 88.4-, 7.8-, >100-, and >100-fold resistance to dithiopyr, prodiamine, pendimethalin, and oryzalin, respectively when compared to the susceptible population based on biomass reduction response. This is the first report of less resistance to prodiamine compared to pendimethalin or oryzalin due to a target-site α-tubulin mutation and the first report of a target-site α-tubulin mutation associated with dithiopyr resistance.