Florida's Organo-Auxin Herbicide Rule—2021

Organo-auxin (phenoxy) herbicides have found a place in weed control schemes for peanut, corn, small grains, sugarcane, turf, pasture and forage crops, and many other areas. It is the intent of this publication to clarify and disseminate the Florida Organo-Auxin Herbicide Rule to interested growers and applicators. Major revision by B. Bultemeier, J. A. Ferrell, and G. E. MacDonald; 4 pages.https://edis.ifas.ufl.edu/wg051

Modeling Grain Rotational Disruption by Radiative Torques and Extinction of Active Galactic Nuclei

Extinction curves observed toward individual Active Galactic Nuclei (AGN) usually show a steep rise toward far-ultraviolet (FUV) wavelengths and can be described by the Small Magellanic Cloud (SMC)-like dust model. This feature suggests the dominance of small dust grains of size a ≤ 0.1 μm in the local environment of AGN, but the origin of such small grains is unclear. In this paper, we aim to explain this observed feature by applying the RAdiative Torque Disruption (RATD) to model the extinction of AGN radiation from FUV to mid-infrared (MIR) wavelengths. We find that in the intense radiation field of AGN, large composite grains of size a ≥ 0.1 μm are significantly disrupted to smaller sizes by RATD up to d RATD > 100 pc in the polar direction and d RATD ∼ 10 pc in the torus region. Consequently, optical–MIR extinction decreases, whereas FUV-near-ultraviolet extinction increases, producing a steep far-UV rise extinction curve. The resulting total-to-selective visual extinction ratio thus significantly drops to R V < 3.1 with decreasing distances to AGN center due to the enhancement of small grains. The dependence of R V with the efficiency of RATD will help us to study the dust properties in the AGN environment via photometric observations. In addition, we suggest that the combination of the strength between RATD and other dust destruction mechanisms that are responsible for destroying very small grains of a ≤ 0.05 μm is the key for explaining the dichotomy observed “SMC” and “gray” extinction curve toward many AGN.

Key Global Actions for Mycotoxin Management in Wheat and Other Small Grains

Mycotoxins in small grains are a significant and long-standing problem. These contaminants may be produced by members of several fungal genera, including Alternaria, Aspergillus, Fusarium, Claviceps, and Penicillium. Interventions that limit contamination can be made both pre-harvest and post-harvest. Many problems and strategies to control them and the toxins they produce are similar regardless of the location at which they are employed, while others are more common in some areas than in others. Increased knowledge of host-plant resistance, better agronomic methods, improved fungicide management, and better storage strategies all have application on a global basis. We summarize the major pre- and post-harvest control strategies currently in use. In the area of pre-harvest, these include resistant host lines, fungicides and their application guided by epidemiological models, and multiple cultural practices. In the area of post-harvest, drying, storage, cleaning and sorting, and some end-product processes were the most important at the global level. We also employed the Nominal Group discussion technique to identify and prioritize potential steps forward and to reduce problems associated with human and animal consumption of these grains. Identifying existing and potentially novel mechanisms to effectively manage mycotoxin problems in these grains is essential to ensure the safety of humans and domesticated animals that consume these grains.

Fusarium head blight of small grains in Pennsylvania: unravelling species diversity, toxin types, growth and triazole sensitivity

Fusarium graminearum is the main causal species of Fusarium head blight (FHB) globally. Recent changes in the trichothecene (toxin) types in the North American FHB pathogens support the need for continued surveillance. In this study, 461 isolates were obtained from symptomatic spikes of wheat, spelt, barley, and rye crops during 2018 and 2019. These were all identified to species and toxin types using molecular-based approaches. An additional set of 77 F. graminearum isolates obtained from overwintering crop residues during Winter 2012 were molecularly identified to toxin types. A subset of 31 F. graminearum isolates (15 15ADON and 16 3ADON) were assessed for mycelial growth, macroconidia, perithecia, and ascospore production, and sensitivity to two triazole fungicides. Ninety percent of isolates obtained from symptomatic spikes (n = 418) belonged to F. graminearum, with another four species found at a lower frequency (n = 39). F. graminearum isolates from symptomatic spikes were mainly of the 15ADON (95%), followed by 3ADON (4%), NIV (0.7%), and NX-2 (0.3%) toxin types. All F. graminearum isolates obtained from overwintering residue were of the 15ADON type. Toxin types could not be differentiated based on multivariate analysis of growth and reproduction traits. All isolates were sensitive to tebuconazole and metconazole fungicides in vitro. This study confirms the dominance of F. graminearum and suggests ecological and environmental factors that lead to similar composition of toxin types in Northern U.S. Our results are useful to assess the sustainability of FHB management practices and provide a baseline for future FHB surveys.

The Potential of Small Grains Crops in Enhancing Biofortification Breeding Strategies for Human Health Benefit

Nutrition is a source of energy, and building material for the human organism. The quality of food has an effect on the quality of individual life. Minerals and vitamins participate in various catalytic and regulatory functions of the main metabolic processes: absorption, transport, redox and biosynthesis of organic compounds, genetic information transfer, etc. Regular consumption of dietary fibers like β-glucans and oat-specific phenolics, antioxidants, and avenanthramides, stimulate innate and acquired immunity, prevent cancer, obesity, reduce glucose, total cholesterol and triglyceride blood levels and regulate the expression of cholesterol-related genes. Thus, all those compounds are vitally important for the normal functional status of the human body. A deficiency in one or another essential nutrient causes disruptions in human metabolism, thus leading to serious illnesses. Plants are the main source of essential nutrients that are bioavailable for humans. One of the most popular groups of staple crops are the small grains crops (SGC), so these crops are most often used for biofortification purposes. Exploiting the potential of plant resources, biofortification is a long-term strategy, aimed at increasing the number of essential micro- and macronutrients in major food sources and ensuring their bioavailability. The most productive way to implement such strategy is the active use of the possibilities offered by collections of plant genetic resources, including SGC, concentrated in various countries of the world. The collections of plant resources contain both cultivated plants and their wild relatives that possess the required composition of micro- and macronutrients. A complex scientific approach to studying plant germplasm collections, together with agricultural practices (soil enrichment with fertilizers with a required composition), genetic biofortification (traditional breeding, marker-assisted selection or genetic engineering tactics), and their combinations will lead to the development of new biofortified cultivars and improvement of old ones, which can be used to solve the problems of unbalanced nutrition (malnutrition or hidden hunger) in different regions of the world.

Identification of Winter Habit Bread Wheat Landraces in the National Small Grains Collection with Resistance to Emerging Stem Rust Pathogen Variants

Wheat stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is a widespread and recurring threat to wheat production. Emerging Pgt variants are rapidly overcoming major gene resistance deployed in wheat cultivars and new sources of race-nonspecific resistance are urgently needed. The National Small Grains Collection (NSGC) contains thousands of wheat landrace accessions that may harbor unique and broadly effective sources of resistance to emerging Pgt variants. All NSGC available facultative and winter-habit bread wheat landraces were tested in a field nursery in St. Paul, MN against a bulk collection of six common U.S. Pgt races. Infection response and severity data were collected on 9,192 landrace accessions at the soft-dough stage and resistant accessions were derived from single spikes. Derived accessions were tested in St. Paul a second time to confirm resistance and in a field nursery in Njoro, Kenya against emerging races of Pgt with virulence to many known resistance genes including Sr24, Sr31, Sr38, and SrTmp. Accessions resistant in the St. Paul field were also tested at the seedling stage with up to 13 Pgt races, including TTKSK and TKTTF, and with 19 molecular markers linked with known stem rust resistance genes or genes associated with modern breeding practices. Forty-five accessions were resistant in both U.S. and Kenya field nurseries and lacked alleles linked with known stem rust resistance genes. Accessions with either moderate or strong resistance in the U.S. and Kenya field nurseries and with novel seedling resistance will be prioritized for further study.