Background: Mixtures of herbicide sites of action (SOA) are often promoted as an effective practice for proactive herbicide resistance management, but the cost of implementation is less-often considered in these recommendations, especially in the academic literature. Objective: Estimate the costs of implementing herbicide SOA mixtures that are effective for herbicide resistance management under different scenarios involving crops, weed species, and existing resistance. Methods: Using data from the Guide for Weed, Disease, and Insect Management in Nebraska, an optimization function [...] Background: Mixtures of herbicide sites of action (SOA) are often promoted as an effective practice for proactive herbicide resistance management, but the cost of implementation is less-often considered in these recommendations, especially in the academic literature. Objective: Estimate the costs of implementing herbicide SOA mixtures that are effective for herbicide resistance management under different scenarios involving crops, weed species, and existing resistance. Methods: Using data from the Guide for Weed, Disease, and Insect Management in Nebraska, an optimization function

Field and greenhouse experiments were conducted from 2013 to 2015 at the University of Wyoming to evaluate the response of Beta vulgaris (L.) to reflected-light quality. Large-pail field studies included a factorial arrangement of three varieties of B. vulgaris (sugar beet, table beet, and Swiss chard) and reflected-light treatments (using either colored plastic mulch, grass, or bare-soil controls). Greenhouse studies included sugar beet as influenced by either grass or soil surroundings. In all studies, grass was grown in separate containers from B. vulgaris, so there was no root interaction. Grass was clipped regularly to prevent shading and competition for sunlight. Reflected light from different-colored plastic mulches (red, blue, green, black, clear) did not affect B. vulgaris growth. However, reflected light from the grass reduced the number of leaves in all B. vulgaris varieties such that there were 10 to 14 fewer leaves in B. vulgaris surrounded by grass compared with the soil treatment at 90 d after planting in the field study. Shade avoidance cues from surrounding grass reduced B. vulgaris total leaf area by 49% to 66%, leaf biomass by 21% to 30%, and root biomass by 70% to 72%. Similar results were observed in greenhouse experiments, where the grass treatment reduced sugar beet leaf biomass by 48% to 57% and root biomass by 35% to 64%. Shade avoidance cues have the potential to significantly reduce B. vulgaris yield, even in the absence of direct resource competition from weeds.

There is a consensus within the scientific community that nitrogenous fertilizers are almost indispensable in today’s agriculture. However, the geometric increase in nitrogenous fertilizer applications and the associated environmental concerns call for focus on more sustainable alternatives. Biological dinitrogen (N2) fixation (BNF) is one of the most sustainable approaches to meeting crop nitrogen (N) demands. The BNF is, especially, important in low value crops (e.g., forages) and in developing economies. However, just like synthetic N fertilizers, BNF has issues of its own. Among the issues of great importance is the low and highly variable proportion of fixed N2 transferred to non-N2-fixing plants. The proportion of transfer ranges from as low as 0% to as high as 70%, depending on a myriad of factors. Most of the factors (e.g., N fertilizer application, species, and cultivar selection) are management related and can, therefore, be controlled for improved N2 fixation and transfer. In this chapter, we discuss current trends in BNF in selected legume crops, the global economics of BNF, and recent reports on N2 transfer in agricultural production systems. Additionally, factors affecting N2 transfer and management considerations for improving N2 fixation and transfer are discussed.