Joseph T. Dauer

Management of Italian Ryegrass (Lolium perenne ssp. multiflorum) in Western Oregon with Preemergence Applications of Pyroxasulfone in Winter Wheat

Abstract Management of Italian ryegrass in cereal-based cropping systems continues to be a major production constraint in areas of the United States, including the soft white winter wheat producing regions of the Pacific Northwest. Pyroxasulfone is a soil-applied herbicide with the potential to control broadleaf and grass weed species, including grass weed biotypes resistant to group 1, 2, and 7 herbicides, in several crops for which registration has been completed or is pending, including wheat, corn, sunflower, dry bean, and soybean. Field experiments were conducted from 2006 through 2009 near Corvallis, OR, to evaluate the potential for Italian ryegrass control in winter wheat with applications of pyroxasulfone. Application rates of PRE treatments ranged from 0.05 to 0.15 kg ai ha−1. All treatments were compared to standard Italian ryegrass soil-applied herbicides used in winter wheat, including diuron, flufenacet, and flufenacet + metribuzin. Visual evaluations of Italian ryegrass and ivyleaf speedwell control and winter wheat injury were made at regular intervals following applications. Winter wheat yields were quantified at grain maturity. Ivyleaf speedwell control was variable, and Italian ryegrass control following pyroxasulfone applications ranged from 65 to 100% and was equal to control achieved with flufenacet and flufenacet + metribuzin treatments and greater than that achieved with diuron applications. Winter wheat injury from pyroxasulfone ranged from 0 to 8% and was most associated with the 0.15–kg ha−1 application rate. However, this early-season injury did not negatively impact winter wheat yield. Pyroxasulfone applied at the application rates and timings in these studies resulted in high levels of activity on Italian ryegrass and excellent winter wheat safety. Based on the results, pyroxasulfone has the potential to be used as a soil-applied herbicide in winter wheat for Italian ryegrass management and its utility for management of other important grass and broadleaf weeds of cereal-based cropping systems should be evaluated. Nomenclature: Diuron; flufenacet; pyroxasulfone; metribuzin; Italian ryegrass, Lolium perenne L. ssp. multiflorum (Lam.) Husnot; ivyleaf speedwell, Veronica hederifolia L.; wheat, Triticum spp.

A unifying gravity framework for dispersal

Most organisms disperse at some life-history stage, but different research traditions to study dispersal have evolved in botany, zoology, and epidemiology. In this paper, we synthesize concepts, principles, patterns, and processes in dispersal across organisms. We suggest a consistent conceptual framework for dispersal, which utilizes generalized gravity models. This framework will facilitate communication among research traditions, guide the development of dispersal models for theoretical and applied ecology, and enable common representation across taxonomic groups, encapsulating processes at the source and destination of movement, as well as during the intervening relocation process, while allowing each of these stages in the dispersal process to be addressed separately and in relevant detail. For different research traditions, certain parts of the dispersal process are less studied than others (e.g., seed release processes in plants and termination of dispersal in terrestrial and aquatic animals). The generalized gravity model can serve as a unifying framework for such processes, because it captures the general conceptual and formal components of any dispersal process, no matter what the relevant biological timescale involved. We illustrate the use of the framework with examples of passive (a plant), active (an animal), and vectored (a fungus) dispersal, and point out promising applications, including studies of dispersal mechanisms, total dispersal kernels, and spatial population dynamics.

Elucidating the Population Dynamics of Japanese Knotweed Using Integral Projection Models

Plant demographic studies coupled with population modeling are crucial components of invasive plant management because they inform managers when in a plant’s life cycle it is most susceptible to control efforts. Providing land managers with appropriate data can be especially challenging when there is limited data on potentially important transitions that occur belowground. For 2 years, we monitored 4 clonal Japanese knotweed ( Polygonum cuspidatum ) infestations for emergence, survival, shoot height until leaf senescence, dry shoot biomass after senescence, and rhizome connections for 424 shoots. We developed an integral projection model using both final autumn shoot height and shoot biomass as predictors of survival between years, growth from year to year, and number of rhizomes produced by a shoot (fecundity). Numbers of new shoots within an infestation (population growth rate λ) were projected to increase 13-233% in a year, with the greatest increase at the most frequently disturbed site. Elasticity analysis revealed population growth at 3 of the 4 sites was primarily due to ramet survival between years and to year-to-year growth in shoot height and shoot biomass. Population growth at the fourth site, the most disturbed, was due to the large production of new rhizomes and associated shoots. In contrast to previous studies, our excavation revealed that most of the shoots were not interconnected, suggesting rhizome production may be limited by the size or age of the plants, resource availability, disturbance frequency, or other factors. Future integration of plant population models with more data on belowground growth structures will clarify the critical stages in Japanese knotweed life cycle and support land managers in their management decisions.

Primary literature across the undergraduate curriculum: teaching science process skills and content

Emily Rauschert, Joseph Dauer, Jennifer L. Momsen, and Ariana Sutton-Grier presented a workshop titled “101 Ways to Effectively Use Journal Articles as Teaching Tools.” They show us a number (not sure there are exactly 101 but who is counting) of ways to use primary literature to meet a multitude of learning objectives, primarily in the undergraduate classroom, but many of the approaches can be used in other settings. They also present some feedback and comments from the participants, so it is almost as if you were there.

Yellow Nutsedge (Cyperus esculentus) Growth and Tuber Production in Response to Increasing Glyphosate Rates and Selected Adjuvants

Abstract Greenhouse studies were conducted to evaluate the influence of selected adjuvants on glyphosate efficacy on yellow nutsedge and tuber production. Glyphosate was applied at 0, 0.25, 0.43, 0.87, 1.26 (1× rate), and 1.74 kg ae ha−1 at 31 d after yellow nutsedge was planted. Each rate was mixed with one of the following adjuvants: ammonium sulfate (AMS), AMS plus nonionic surfactant (NIS), or AMS plus an experimental adjuvant (W-7995) plus NIS. Plants were evaluated for injury and for the number and size of tubers produced. Dose–response curves based on log-logistic models were used to determine the effective glyphosate rate plus adjuvant that provided both 90% effective dose (ED90) for yellow nutsedge injury and reduced tuber production. Addition of NIS to glyphosate plus AMS resulted in the greatest yellow nutsedge injury at 28 d after treatment (DAT). Addition of the experimental adjuvant plus NIS resulted in injury similar to NIS alone. The ED90 for injury at 28 DAT was 2.12 kg ha−1 with glyphosate plus AMS and NIS compared with 2.18 kg ha−1 for W-7995 plus NIS and 3.06 kg ha−1 with AMS alone. The ED90 rates with different adjuvants represent 168%, 173%, and 243% of the highest glyphosate rate (1.26 kg ha−1) labeled for application on many glyphosate-resistant crops. However, the estimated ED90 to reduce small, medium, large, and total tubers were 1.60, 1.50, 1.63, and 1.66 kg ha−1, respectively. Increases in labeled rates of glyphosate may be required to reduce yellow nutsedge tuber production in field conditions. Use of lower glyphosate rates should be discouraged because it may increase tuber production and exacerbate yellow nutsedge expansion in infested fields. Nomenclature: Glyphosate; yellow nutsedge, Cyperus esculentus L. CYPES.

Gene flow from single and stacked herbicide-resistant rice (Oryza sativa): modeling occurrence of multiple herbicide-resistant weedy rice

BACKGROUND Provisia™ rice (PV), a non-genetically engineered (GE) quizalofop-resistant rice, will provide growers with an additional option for weed management to use in conjunction with Clearfield® rice (CL) production. Modeling compared the impact of stacking resistance traits versus single traits in rice on introgression of the resistance trait to weedy rice (also called red rice). Common weed management practices were applied to 2-, 3- and 4-year crop rotations, and resistant and multiple-resistant weedy rice seeds, seedlings and mature plants were tracked for 15 years. RESULTS Two-year crop rotations resulted in resistant weedy rice after 2 years with abundant populations (exceeding 0.4 weedy rice plants m-2 ) occurring after 7 years. When stacked trait rice was rotated with soybeans in a 3-year rotation and with soybeans and CL in a 4-year rotation, multiple-resistance occurred after 2-5 years with abundant populations present in 4-9 years. When CL rice, PV rice, and soybeans were used in 3- and 4-year rotations, the median time of first appearance of multiple-resistance was 7-11 years and reached abundant levels in 10-15 years. CONCLUSION Maintaining separate CL and PV rice systems, in rotation with other crops and herbicides, minimized the evolution of multiple herbicide-resistant weedy rice through gene flow compared to stacking herbicide resistance traits.

Simulated Computational Model Lesson Improves Foundational Systems Thinking Skills and Conceptual Knowledge in iology Students

It is important for undergraduate biology students to understand biological phenomena from a systems perspective because it is important for solving world problems related to the life sciences (e.g., medical and environmental). Unfortunately, students have few opportunities to develop the skills and conceptual knowledge required for a systems perspective. Simulated computational models are promising tools to help students achieve a systems perspective. We examined one lesson that uses simulations of a computational model to teach students about cellular respiration, and we report on its effectiveness to improve systems thinking skills and conceptual knowledge. Concept models revealed that the lesson helped the students identify, relate, and interconnect the components of cellular respiration, thereby improving aspects of their systems thinking skills and conceptual knowledge. We discuss how learning was affected by how the students interacted with the computational model.

Introductory Biology Students’ Use of Enhanced Answer Keys and Reflection Questions to Engage in Metacognition and Enhance Understanding

This study examined the use of enhanced answer keys and reflection questions to support introductory biology students to engage in metacognition. The scaffolds supported students to consider their own understanding. Students who received directed instruction on the use of scaffolds had even greater benefit than students who received only the scaffolds.

Programmatic access to logical models in the Cell Collective modeling environment via a REST API.

UNLABELLED Cell Collective (www.cellcollective.org) is a web-based interactive environment for constructing, simulating and analyzing logical models of biological systems. Herein, we present a Web service to access models, annotations, and simulation data in the Cell Collective platform through the Representational State Transfer (REST) Application Programming Interface (API). The REST API provides a convenient method for obtaining Cell Collective data through almost any programming language. To ensure easy processing of the retrieved data, the request output from the API is available in a standard JSON format. AVAILABILITY AND IMPLEMENTATION The Cell Collective REST API is freely available at http://thecellcollective.org/tccapi. All public models in Cell Collective are available through the REST API. For users interested in creating and accessing their own models through the REST API first need to create an account in Cell Collective (http://thecellcollective.org). CONTACT thelikar2@unl.edu. SUPPLEMENTARY INFORMATION Technical user documentation: https://goo.gl/U52GWo.