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The past 50 years of advances in weed recognition technologies have poised site-specific weed control (SSWC) on the cusp of requisite performance for large-scale production systems. The technology offers improved management of diverse weed morphology over highly variable background environments. SSWC enables the use of non-selective weed control options, such as lasers and electrical weeding, as feasible in-crop selective alternatives to herbicides by targeting individual weeds. This review looks at the progress made over this half-century of research and its implications for future weed recognition and control efforts; summarizing advances in computer vision techniques and the most recent deep convolutional neural network (CNN) approaches to weed recognition. The first use of CNNs for plant identification in 2015 began an era of rapid improvement in algorithm performance on larger and more diverse datasets. These performance gains and subsequent research have shown that the variability of large-scale cropping systems is best managed by deep learning for in-crop weed recognition. The benefits of deep learning and improved accessibility to open-source software and hardware tools has been evident in the adoption of these tools by weed researchers and the increased popularity of CNN-based weed recognition research. The field of machine learning holds substantial promise for weed control, especially the implementation of truly integrated weed management strategies. While previous approaches sought to reduce environmental variability or manage it with advanced algorithms, research in deep learning architectures suggests that large-scale, multi-modal approaches are the future for weed recognition.
Rigid ryegrass is a problematic weed species in winter crops and winter fallow; however, recently, this weed species has been observed in summer crops and fallow. These observations warrant the evaluation of different postemergence herbicides for its control. Outdoor pot studies were conducted during the spring and summer of 2021 to 2022 to determine the performance of POST herbicides on two summer-emerging (S3 and S6) and two winter-emerging (W3 and W8) accessions of rigid ryegrass. Across all accessions, butroxydim, clethodim, paraquat, and paraquat + amitrole at the field rate provided complete control of rigid ryegrass. Both summer-emerging accessions were found to be resistant to the field rates of glufosinate (750 g ai ha−1), glyphosate (454 g ae ha−1), haloxyfop (52 g ai ha−1), and pinoxaden (30 g ai ha−1). The S6 accession had the highest dose required for a 50% reduction in biomass for these herbicides (glufosinate 1,120 g ai ha−1, glyphosate 1,210 g ae ha−1, haloxyfop 140 g ai ha−1, and pinoxaden 55 g ai ha−1). This summer-emerging accession (S6) was also resistant to iodosulfuron. All four accessions were found susceptible to imazamox + imazapyr (a commercial mixture) and mesosulfuron. The study provides the first evidence of poor control of summer-emerging accessions of rigid ryegrass with different herbicides. Multiple-herbicide-resistant summer-emerging rigid ryegrass accessions would be a challenge to the production of summer crops (e.g., cotton and sorghum) as well as winter crops that rely on weed-free summer fallows for soil moisture retention; therefore these accessions warrant diversified management strategies.
Italian ryegrass is a major weed in winter cereals in the south-central United States. Harvest weed seed control (HWSC) tactics that aim to remove weed seed from crop fields are a potential avenue to reduce Italian ryegrass seedbank inputs. To this effect, a 4-yr, large-plot field study was conducted in College Station, Texas, and Newport, Arkansas, from 2016 to 2019. The treatments were arranged in a split-plot design. The main-plot treatments were (1) no narrow-windrow burning (a HWSC strategy) + disk tillage immediately after harvest, (2) HWSC + disk tillage immediately after harvest, and (3) HWSC + disk tillage 1 mo after harvest. The subplot treatments were (1) pendimethalin (1,065 g ai ha−1; Prowl H2O®) as a delayed preemergence application (herbicide program #1), and (2) a premix of flufenacet (305 g ai ha−1) + metribuzin (76 g ai ha−1; Axiom®) mixed with pyroxasulfone (89 g ai ha−1; Zidua® WG) as an early postemergence application followed by pinoxaden (59 g ai ha−1; Axial® XL) in spring (herbicide program #2). After 4 yr, HWSC alone was significantly better than no HWSC. Herbicide program #2 was superior to herbicide program #1. Herbicide program #2 combined with HWSC was the most effective treatment. The combination of herbicide program #1 and standard harvest practice (no HWSC; check) led to an increase in fall Italian ryegrass densities from 4 plants m−2 in 2017 to 58 plants m−2 in 2019 at College Station. At wheat harvest, Italian ryegrass densities were 58 and 59 shoots m−2 in check plots at College Station and Newport, respectively, whereas the densities were near zero in plots with herbicide program #2 and HWSC at both locations. These results will be useful for developing an improved Italian ryegrass management strategy in this region.
Wild radish is the most problematic broadleaf weed in Australian grain production. The propensity of wild radish to evolve resistance to herbicides has led to high frequencies of multiple herbicide–resistant populations present in these grain production regions. The objective of this study was to evaluate the potential of mesotrione to selectively control wild radish in wheat. The initial dose response pot trials determined that at the highest mesotrione rate of 50 g ha−1 applied preemergence (PRE) was 30% more effective than when applied postemergence (POST) on wild radish. This same rate of mesotrione applied POST resulted in a 30% reduction in wheat biomass compared to 0% for the PRE application. Subsequent mesotrione PRE dose response trials identified a wheat selective rate range of >100 and <300 g ai ha−1 that provided greater than 85% wild radish control with less than 15% reduction in wheat growth. Field evaluations confirmed the efficacy of mesotrione at 100 to 150 g ai ha−1 in reducing wild radish populations by greater than 85% following PRE application and incorporation by wheat planting. Additionally, these field trials demonstrated the opportunity for season-long control of wild radish when mesotrione applied PRE was followed by bromoxynil applied POST. The sequential PRE application of mesotrione, a herbicide that inhibits p-hydroxyphenylpyruvate dioxygenase, followed by POST application of bromoxynil, a herbicide that inhibits photosystem II, has the potential to provide 100% wild radish control with no effect on wheat growth.
The recent FDA marketing authorizations granted for testing for mutations associated with hereditary breast and colon cancer, as well as pharmacogenomic susceptibilities, provide an opportunity to re-examine the medical as well as regulatory underpinnings of DTC genetic testing. In this chapter, we first examine the historical emergence of enabling technologies that have provided for the availability of DNA sequence information on a broad scale, the efforts by the medical community to incorporate these advances into models of “precision” or “personalized” medicine, and the risks and benefits of offering access to DNA germline sequence analysis outside of the traditional medical model. We then turn to the current and proposed regulatory schemes to provide oversight over DTC genetic testing, with a focus on the role of the FDA as an information regulator and guardian of public health and safety.
Junglerice and feather fingergrass are major problematic weeds in the summer sorghum cropping areas of Australia. This study aimed to investigate the growth and seed production of junglerice and feather fingergrass in crop-free (fallow) conditions and under competition with sorghum planted in 50-cm and 100-cm row spacings at three sorghum planting and weed emergence timings. Results revealed that junglerice and feather fingergrass had greater biomass in early planting (November 11) compared to late planting times (January 11). Under fallow conditions, seed production of junglerice ranged from 12,380 to 20,280 seeds plant–1, with the highest seed production for the December 11 and lowest for the January 11 planting. Seed production of feather fingergrass under fallow conditions ranged from 90,030 to 143,180 seeds plant–1. Seed production of feather fingergrass under crop-free (fallow) conditions was similar for November 11 and December 11 planting times, but higher for the January 11 planting. Sorghum crop competition at both row spacings reduced the seed production of junglerice and feather fingergrass >75% compared to non-crop fallow. Narrow row spacing (50 cm) in early and mid-planted sorghum (November 11 and December 11) reduced the biomass of junglerice to a greater extent (88% to 92% over fallow-grown plants) compared to wider row spacing (100 cm). Narrow row spacing was found superior in reducing biomass of feather fingergrass compared to wider row spacing. Our results demonstrate that sorghum crops can substantially reduce biomass and seed production of junglerice and feather fingergrass through crop competition compared with growth in fallow conditions. Narrow row spacing (50 cm) was found superior to wider row spacing (100 cm) in terms of weed suppression. These results suggest that narrow row spacing and late planting time of sorghum crops can strengthen an integrated weed management program against these weeds by reducing weed growth and seed production.
Introduction to Education provides pre-service teachers with an overview of the context, craft and practice of teaching in Australian schools as they commence the journey from learner to classroom teacher. Each chapter poses questions about the nature of teaching students, and guides readers though the Australian Professional Standards for Teachers. Incorporating recent research and theoretical literature, Introduction to Education presents a critical consideration of the professional, policy and curriculum contexts of teaching in Australia. The book covers theoretical topics in chapters addressing assessment, planning, safe learning environments, and working with colleagues, families, carers and communities. More practical chapters discuss professional experience and building a career after graduation. Rigorous in conception and practical in scope, Introduction to Education welcomes new educators to the theory and practical elements of teaching, learning, and professional practice.