Cover crops, hormones and herbicides: Priming an integrated weed management strategy.

Herbicide weed resistance has been a major issue of conventional global row crop agriculture for decades. Still current strategies and novel technologies available to address weed resistance are mainly herbicide-based. Thus, there is a need for innovative means of integrated weed management strategies. Our approach proposed herein integrates cover crops, plant hormones and pre-emergence (PRE) herbicides as part of weed management programs. Plant hormones such as gibberellic acid (GA3) and abscisic acid (ABA) have the potential to induce seed germination and seed dormancy, respectively. Prior to crop emergence, plant hormones are tank mixed with PRE herbicides and sprayed to cover crop residue. Two strategies are proposed (1) PRE herbicides + GA3 and (2) PRE herbicide + ABA. The hormones provide different results; GA3 is likely to stimulate a more uniform weed seed germination, thus enhancing efficacy of PRE herbicides. Conversely, ABA could promote weed seed dormancy, reducing selection pressure and weed infestations until crop canopy closure. Much research is needed to understand the impact of hormones on weed and crop species, optimize products and rates, and compatibility of hormones with herbicides and cover crops. If successful, this approach could open a new opportunity for agricultural business, enhance farming sustainability by reducing dependence on herbicides and minimizing agronomic, economic and environmental issues related to weed resistance.

Hapten Synthesis, Antibody Development, and a Highly Sensitive Indirect Competitive Chemiluminescent Enzyme Immunoassay for Detection of Dicamba.

Although dicamba has long been one of the most widely used selective herbicides, some U.S. states have banned the sale and use of dicamba because of farmers complaints of drift and damage to nonresistant crops. To prevent illegal use of dicamba and allow monitoring of nonresistant crops, a rapid and sensitive method for detection of dicamba is critical. In this paper, three novel dicamba haptens with an aldehyde group were synthesized, conjugated to the carrier protein via a reductive-amination procedure and an indirect competitive chemiluminescent enzyme immunoassay (CLEIA) for dicamba was developed. The assay showed an IC50 of 0.874 ng/mL which was over 15 times lower than that of the conventional enzyme immunoassay. The immunoassay was used to quantify dicamba concentrations in field samples of soil and soybean obtained from fields sprayed with dicamba. The developed CLEIA showed an excellent correlation with LC-MS analysis in spike-and-recovery studies, as well as in real samples. The recovery of dicamba ranged from 86 to 108% in plant samples and from 105 to 107% in soil samples. Thus, this assay is a rapid and simple analytical tool for detecting and quantifying dicamba levels in environmental samples and potentially a great tool for on-site crop and field monitoring.