Evaluation and Utilization of Allelopathic Festuca rubra Turfgrass Cultivars for Alternative Weed Management Strategies

Recent experiments in Ithaca and Riverhead NY have shown that fine fescue cultivars Intrigue, Reliant, and Oxford were most suppressive in field and laboratory settings due to their allelopathic activity and their ability to establish readily in a field setting. The cultivars Treasure and Boreal were least weed suppressive in both sites in 2 years of replicated trials. Mode of action studies would suggest the inhibitor(s) in the root exudate act upon photosynthesis or respiration or possibly both. Current anatomical studies suggest root exudates are produced in actively dividing root cells and are stored until extrusion from roots in osmiophilic inclusions in root cells. The structural elucidation studies performed using GC and HPLC coupled to mass spectrometry suggest that the components of the root exudates may be steroidal in nature. Purification and structural elucidation work is ongoing

Evaluation and Utilization of Allelopathic Festuca rubra Turfgrass Cultivars and Selected Groundcovers for Alternative Weed Management Strategies in the Landscape

ReportThe development of alternative weed management strategies in landscape and turf settings involves the use and implementation of novel bio-control practices which can provide efficaceous control over the course of the growing season. Use of pathogenic organisms to control weeds has not proven particularly effective, due to problems in obtaining consistent control and difficulty in formulation of biocontrol organisms. Organically derived products, such as corn gluten or cramby meal, have also not provided consistent or inexpensive control, especially in commercial settings such as golf courses, parks and athletic fields where complete control is often desirable. One novel approach which shows strong potential is the selection, development and use of allelopathic or weed suppressive turfgrasses or groundcovers to naturally control annual weeds in the landscape, without the use of herbicides. Fescues, especially Festuca rubra spp., produce secondary products known as allelochemicals with potent ability to suppress weed seed germination and growth

Biological Control of Ground Ivy Using a Rust Fungus

Ground-ivy or creeping Charlie (Glechoma hederacea) is a creeping perennial in the Mint Family that forms dense prostrate patches in turfgrass, damp shady meadows, and disturbed sites. The control of ground ivy using chemical and mechanical methods has largely been unsuccessful in turfgrass where it is considered a major weed. Thus, there is a pressing need to develop and evaluate alternative approaches for the control of ground ivy in turfgrass that are effective and environmentally sound

Recent developments in primer design for DNA polymorphism and mRNA profiling in higher plants

Primer design is a critical step in the application of PCR-based technologies in gene expression and genetic diversity analysis. As more plant genomes have been sequenced in recent years, the emphasis of primer design strategy has shifted to genome-wide and high-throughput direction. This paper summarizes recent advances in primer design for profiling of DNA polymorphism and mRNA in higher plants, as well as new primer systems developed for animals that can be adapted for plants

Opportunities and Challenges for Cover Cropping in Sustainable Agriculture Systems in Southern Australia

Southern Australian farming systems operate predominantly under Mediterranean climatic conditions, which limit the choice of cover crops suitable for enhancement of ground cover and soil moisture retention, erosion control, atmospheric soil nitrogen (N) fixation, and weed suppression between cash crop rotations. Given that the successful establishment of cover crops is climate-driven and also influenced by edaphic factors such as soil pH and salinity, there has been increased interest by southern Australian producers in identifying potential cover crop species well adapted to specific Australian farming systems, which provide vital ecosystem services and sustainable economic benefits through the improvement of soil properties. This review summarises recent findings on cover crop inclusion in diverse farming systems in southern Australia, including continuous and mixed broadacre cropping as well as viticulture and horticulture systems, to identify opportunities and limitations related to their use. Cover crop inclusion in viticulture and pasture systems with lower moisture stress was observed to benefit the subsequent cash crop through enhanced production potential. Long-term, multi-site field experimentation incorporating summer cover crops in winter crop rotations showed that cover crops enhanced ground cover and soil water infiltration in some locations across southern Australia while sometimes increasing winter crop yield, suggesting that soil type and regional climatic conditions greatly influenced the delivery of multiple cover crop benefits. Collectively, these studies have suggested a need for longer-term field evaluations using multiple cover crop species and investigations of termination options under varying environmental and soil conditions to better quantify the legacy effects of cover crops

Possibilities for rationally exploiting co-evolution in addressing resistance to insecticides, and beyond

Certain biorational chemical agents used against insect pests impact essential stages or processes in insect life cycles when applied for pest management. Development of resistance to these agents, while involving maintenance of the natural role of the chemical agent, frequently requires the evolution of a new chemical structure by the resistant organism. When considering the process of resistance development, one could theoretically consider biorational structural determination rather than the less predictable or feasible generation of a novel replacement insecticide. At first consideration, this process might exclude toxicants such as typical pest control agents and rather be a phenomenon reserved principally for signalling processes such as are fulfilled by pheromones and other semiochemicals. However, because there is a unique co-evolutionary relationship between chemical defence and the physiology of the antagonistic organism, this process can be further explored for potential to overcome resistance to toxins. Given further consideration, newly evolved chemical defences may rationally provide options for new resistance-defeating chemistry. This review therefore discusses the potential for overcoming insecticide resistance through targeted application of this approach. Potential for use of a similar approach to counteract fungicide and herbicide resistance is also considered. Furthermore, the possible applications of this approach to address drug or pharmaceutic resistance are also considered

Machine Learning approaches to protein ranking: discriminative, semi-supervised, scalable algorithms

A key tool in protein function discovery is the ability to rank databases of proteins given a query amino acid sequence. The most successful method so far is a web-based tool called PSI-BLAST which uses heuristic alignment of a profile built using the large unlabeled database. It has been shown that such use of global information via an unlabeled data improves over a local measure derived from a basic pairwise alignment such as performed by PSI-BLAST's predecessor, BLAST. In this article we look at ways of leveraging techniques from the field of machine learning for the problem of ranking. We show how clustering and semi-supervised learning techniques, which aim to capture global structure in data, can significantly improve over PSI-BLAST

Metabolic profiling and identification of shikonins in root periderm of two invasive Echium spp. weeds in Australia

Metabolic profiling can be successfully implemented to analyse a living system's response to environmental conditions by providing critical information on an organism's physiological state at a particular point in time and allowing for both quantitative and qualitative assessment of a specific subset(s) of key metabolites. Shikonins are highly reactive chemicals that affect various cell signalling pathways and possess antifungal, antibacterial and allelopathic activity. Based on previous bioassay results, bioactive shikonins, are likely to play important roles in the regulation of rhizosphere interactions with neighbouring plants, microbes and herbivores. An effective platform allowing for rapid identification and accurate profiling of numerous structurally similar, difficult-to-separate bioactive isohexenylnaphthazarins (shikonins) was developed using UHPLC Q-TOF MS. Root periderm tissues of the invasive Australian weeds Echium plantagineum and its congener E. vulgare were extracted overnight in ethanol for shikonin profiling. Shikonin production was evaluated at seedling, rosette and flowering stages. Five populations of each species were compared for qualitative and quantitative differences in shikonin formation. Each species showed little populational variation in qualitative shikonin production; however, shikonin was considerably low in one population of E. plantagineum from Western New South Wales. Seedlings of all populations produced the bioactive metabolite acetylshikonin and production was upregulated over time. Mature plants of both species produced significantly higher total levels of shikonins and isovalerylshikonin > dimethylacrylshikonin > shikonin > acetylshikonin in mature E. plantagineum. Although qualitative metabolic profiles in both Echium spp. were nearly identical, shikonin abundance in mature plant periderm was approximately 2.5 times higher in perennial E. vulgare extracts in comparison to those of the annual E. plantagineum. These findings contribute to our understanding of the biosynthesis of shikonins in roots of two related invasive plants and their expression in relation to plant phenological stage.This research was a part of the Australian Research Council project developed by and granted to L.A.W., G.M.G. and R.M.C., D.

Differences in invasibility of two contrasting habitats and invasiveness of two mugwort Artemisia vulgaris populations

Summary 1. Establishment success of non-native invasive species is often attributable either to habitat invasibility or inherent species traits. In this study we explored the interplay between these two factors in the establishment, expansion and plasticity in growth of the clonally reproducing invasive weed mugwort Artemisia vulgaris in two contrasting habitats, as well as the potential management practice of monthly mowing. 2. We investigated resource allocation patterns and spatial distribution of ramets originating from two naturalized populations over a 3-year period. Ramets from these morphologically distinct populations were transplanted into each of two contrasting habitats to determine the invasive potential of these populations and the relative resistance of each habitat to invasion. 3. Total ramet production, average ramet height and spatial distribution patterns differed significantly between the two populations, but the degree of variation in the response was habitat dependent. There were no interpopulation differences in total biomass production. Plastic responses in resource allocation patterns, spatial distribution of ramets and relative growth rates were observed, demonstrating differences in invasive potential between the two mugwort populations. 4. The two habitats differed in invasibility. This could have been the result of differences in community structure, competition for available resources, disturbance and/or invader traits. In addition, monthly defoliation (mowing) reduced mugwort ramet production by as much as 90% and as little as 10%. 5. Synthesis and applications. This study demonstrates that variation exists in habitat invasibility, and that intraspecific variation in growth patterns occurs in mugwort. The interaction between habitat traits and species characteristics was found to be important when determining invasion success. We also demonstrated that monthly mowing following the introduction of mugwort can substantially decrease the rate of spread of this clonal species, which may provide an effective management opportunity both for this species and for other clonal invaders