EC73-130 A 1973 Guide for Herbicide Use in Nebraska

Extension Circular 73-130 is a 1973 Guide for Herbicide Use in Nebraska

Measurements of Aerosol Size Distributions and Vertical Fluxes of Aerosols on Land Subject to Wind Erosion

To assess wind erosion as a source of atmospheric soil particles, vertical aerosol fluxes near the ground in an eroding field were computed by assuming a vertical transport mechanism similar to that for momentum. Aerosol gradients were measured by jet impactors located 1.5 and 6 m above the ground, and wind velocity gradients were measured by totalizing-three anemometers located 1.5, 3 and 6 m above the ground. Information on the aerosol size distributions and quantity in the size range 0.

Measurements of Aerosol Size Distributions and Vertical Fluxes of Aerosols on Land Subject to Wind Erosion

To assess wind erosion as a source of atmospheric soil particles, vertical aerosol fluxes near the ground in an eroding field were computed by assuming a vertical transport mechanism similar to that for momentum. Aerosol gradients were measured by jet impactors located 1.5 and 6 m above the ground, and wind velocity gradients were measured by totalizing-three anemometers located 1.5, 3 and 6 m above the ground. Information on the aerosol size distributions and quantity in the size range 0.

Development of Highly Variable Microsatellite Markers for the Tetraploid Silene stellata (Caryophyllaceae)

Premise of the study:We designed and tested microsatellite markers for the North American native species Silene stellata (Caryophyllaceae) to investigate its population genetic structure and identify selection on floral design through male reproductive success. Methods and Results: A total of 153 candidate microsatellite loci were isolated based on next-generation sequencing. We identified 18 polymorphic microsatellite loci in three populations of S. stellata, with di- or trinucleotide repeats. Genotyping results showed the number of alleles per locus ranged from six to 45 and expected heterozygosity ranged from 0.511 to 0.951. Five of these loci were successfully amplified in S. virginica and S. caroliniana and were also polymorphic. Conclusions: The microsatellite markers reported here provide a valuable tool for paternity analysis in S. stellata. They will also be useful for investigating the population genetic structures of S. stellata and related species

Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity.

Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs. However, this combination is currently less common than predicted at equilibrium because the individual characters evolve infrequently. Simulations suggest that angiosperms will remain far from the equilibrium frequencies of character states well into the future. Such non-equilibrium dynamics may be common when major innovations evolve rarely, allowing lineages with ancestral forms to persist, and even outnumber those with diversification-enhancing states, for tens of millions of years

The case for the continued use of the genus name Mimulus for all monkeyflowers

The genus Mimulus is a well-studied group of plant species, which has for decades allowed researchers to address a wide array of fundamental questions in biology (Wu & al. 2008; Twyford & al. 2015). Linnaeus named the type species of Mimulus (ringens L.), while Darwin (1876) used Mimulus (luteus L.) to answer key research questions. The incredible phenotypic diversity of this group has made it the focus of ecological and evolutionary study since the mid-20th century, initiated by the influential work of Clausen, Keck, and Hiesey as well as their students and collaborators (Clausen & Hiesey 1958; Hiesey & al. 1971, Vickery 1952, 1978). Research has continued on this group of diverse taxa throughout the 20th and into the 21st century (Bradshaw & al. 1995; Schemske & Bradshaw 1999; Wu & al. 2008; Twyford & al. 2015; Yuan 2019), and Mimulus guttatus was one of the first non-model plants to be selected for full genome sequencing (Hellsten & al. 2013). Mimulus has played a key role in advancing our general understanding of the evolution of pollinator shifts (Bradshaw & Schemske 2003; Cooley & al. 2011; Byers & al. 2014), adaptation (Lowry & Willis 2010; Kooyers & al. 2015; Peterson & al. 2016; Ferris & Willis 2018; Troth & al. 2018), speciation (Ramsey & al. 2003; Wright & al. 2013; Sobel & Streisfeld 2015; Zuellig & Sweigart 2018), meiotic drive (Fishman & Saunders 2008), polyploidy (Vallejo-Marín 2012; Vallejo-Marín & al. 2015), range limits (Angert 2009; Sexton et al. 2011; Grossenbacher & al. 2014; Sheth & Angert 2014), circadian rhythms (Greenham & al. 2017), genetic recombination (Hellsten & al. 2013), mating systems (Fenster & Ritland 1994; Dudash & Carr 1998; Brandvain & al. 2014) and developmental biology (Moody & al. 1999; Baker & al. 2011, 2012; Yuan 2019). This combination of a rich history of study coupled with sustained modern research activity is unparalleled among angiosperms. Across many interested parties, the name Mimulus therefore takes on tremendous biological significance and is recognizable not only by botanists, but also by zoologists, horticulturalists, naturalists, and members of the biomedical community. Names associated with a taxonomic group of this prominence should have substantial inertia, and disruptive name changes should be avoided. As members of the Mimulus community, we advocate retaining the genus name Mimulus to describe all monkeyflowers. This is despite recent nomenclature changes that have led to a renaming of most monkeyflower species to other genera.Additional co-authors: Jannice Friedman, Dena L Grossenbacher, Liza M Holeski, Christopher T Ivey, Kathleen M Kay, Vanessa A Koelling, Nicholas J Kooyers, Courtney J Murren, Christopher D Muir, Thomas C Nelson, Megan L Peterson, Joshua R Puzey, Michael C Rotter, Jeffrey R Seemann, Jason P Sexton, Seema N Sheth, Matthew A Streisfeld, Andrea L Sweigart, Alex D Twyford, John H Willis, Kevin M Wright, Carrie A Wu, Yao-Wu Yua

G81-546 Ecofarming: Fallow Aids in Winter Wheat-Fallow Rotation

This NebGuide discusses the use of ecofarming to control weeds and manage crop residues. Ecofarming is defined as a system of controlling weeds and managing crop residues throughout a crop rotation with minimum use of tillage so as to reduce soil erosion and production costs while increasing weed control, water infiltration, moisture conservation and crop yields. Energy requirements are much lower with ecofallow than with normal fallow systems. The ecofallow period in the 3-year rotation is the period between wheat or other small grain harvest and the planting of corn or sorghum. The fallow period in the 2-year rotation occurs between wheat harvest and the planting of winter wheat 14 months later. Ecofallow means controlling weeds during the fallow period by using herbicides and/or tillage with minimum disturbance of crop residues and soils. We have been working on the ecofallow concept for 20 years, and it is presently being used in the winter wheat-fallow rotation and the winter wheat-corn or sorghum-fallow rotations. The winter wheat-fallow rotation is commonly used in western Nebraska. The 3-year rotation consists of winter wheat-ecofallow-sorghum or corn-fallow. The fallow period after corn or sorghum is followed by winter wheat. This rotation is generally used in the areas that receive 16 to 20 inches of precipitation. In eastern Nebraska, this could be an oats-ecofallow-corn, sorghum or soybean rotation

Root Development of Winter Wheat as Related to Tillage Practice in Western Nebraska

Tillage practices can influence crop root development. Root distributions were determined for wheat (Triticum aestivum L.) grown in a wheat-fallow rotation during the 1977-1978 winter wheat crop year on an Alliance silt loam (Aridic Argiustoll). The fallow tillage treatments were plow, subtillage, and chemical (no tillage). Each tillage treatment was split into subplots for N application of 0 or 45 kg/ha. Rooting density was determined by washing the roots in soil cores 7.6 cm in diam by 15 cm long extracted to depths of 90, 105, and 120 cm on 28 Mar., 2 May, and 8 June 1978, respectively. After root length was determined, roots were dried and weighed. Soil penetration resistance was determined with depth in the soil by inserting a penetrometer horizontally 4 cm into the soil at vertical intervals of 10 cm from the surface. Root weight was greatest for the chemical treatment (46 mg/dm3) and least for the subtillage treatment (26 mg/dm3). Approximately 62% of the total root mass was in the upper 30 cm of soil with maximum rooting depth greater than 120 cm for all treatments by 8 June 1978. Root development was limited by the alluvial horizon at a depth of about 25 to 40 cm. Visual observations also showed some root resistance by tillage shear plane at 10 cm. Nitrogen fertilization did not significantly change the rooting pattern; however, the N-by-tillage interaction for root weight was significant at the second sampling date-the subtillage treatment showed a positive response to added N, while chemical and plow treatments showed a negative response. Wheat yields were not significantly influenced by fallow tillage or N. This indicated that root development occurring above and below the resistant layer was sufficient to supply the plant with its water and mineral needs

G81-550 Ecofarming Operating High Capacity Sprayers (Floaters) for Herbicide Application

This NebGuide will help you determine whether you are covered by or exempt from the Worker Protection Standard and provide information on how to comply. Many flotation sprayers are only used to spray fertilizers and herbicides in the spring. Ecofarming, however, represents a March to November market for them. Successful ecofarming requires precision spraying of herbicides on the winter wheat stubble, and offers tremendous opportunities for professional applicators. Commercial application eliminates some of the field work for the farmer, which is an important element for more efficient farming. The commercial applicator is also able to do a better job since he spends more time spraying and thus is able to afford better equipment. However, timeliness is important and the commercial operator must be careful to avoid becoming overcommitted

G79-436 Control of Downy Brome in Alfalfa

Downy brome in alfalfa indicates poor alfalfa management or failure to control downy brome around field boundaries. It lowers the quality of the first cutting of hay, but can be controlled by one or more of the following: (1) planting in downy brome-free soil, (2) maintaining good vigorous alfalfa stands, (3) using adapted varieties, (4) having adequate fertility - especially phosphorus in the soil, (5) applying timely and correct amounts of irrigation water, (6) controlling downy brome in adjacent areas, and (7) use of herbicides