Agroforestry: integrating apple and arable production as an approach to reducing copper use in organic and low-input apple production

Integrating top fruit production into an agroforestry system, where trees are integrated with arable crop production may have a beneficial effect on the control of plant pathogens such as scab (Venturia inaequalis). Apple yields and pest and disease levels were assessed in a novel apple/arable agroforestry system in Suffolk, and compared with a modern local organic orchard in 2012. Despite 2012 being a very bad year for apple production in the UK, apple yields in the agroforestry system appeared to be comparable with standard figures when scaled up from 2.5% land area under apple production to 100% apples, and even at just 2.5% cover, outperformed the organic orchard used for comparison. Initial indications are that scab levels were over twice as high in the organic orchard than in the agroforestry, indicating that this approach may offer some potential in reducing copper use in organic apple production. However, further research will be required to confirm these early results

A cost-effectiveness analysis of temperate silvoarable systems: what contribution do ecosystem services make?

Silvoarable systems have the potential to be an effective and productive form of sustainable agriculture, in part due to the enhancement of biodiversity and associated ecosystem services. However, currently there is limited understanding of how higher biodiversity in silvoarable systems promotes ecosystem services, such as pest regulation, pollination and nutrient cycling (for example, see Peng et al. 1993; Thevathasan and Gordon 2004; Varah et al. 2013), versus ecosystem disservices, such as encouraging certain pests and weeds (Griffiths et al. 1998; Burgess et al. 2003), and, furthermore, how this cost-benefit ratio might change with how the system is designed, managed and matures over time (but see Burgess et al 2003; Stamps et al. 2009). This paper reports on preliminary results of a cost effectiveness analysis based on the FarmSAFE model (Graves et al. 2011; 2016), as part of a PhD investigating how management of silvoarable influences biodiversity-derived ecosystem services, and their economic implications. Our study is focussed on silvoarable systems in the UK that combine top-fruit production with arable alley-cropping, which are emerging as a promising design with limited shade effects (Smith et al. 2016). We compare our findings to a monocropped arable system, with and without purported associated biodiversity benefits (Varah et al. 2013, 2015)

Applications of crop competitive ability in winter oats (Avena sativa L.)

Crop competition is a key component of an integrated approach to weed management. Variation in competitive ability and competitive traits have been identified in many other crop species, however little work has been done on oats. Trials were carried out over four years at one organic site with five husked and three naked oat varieties. Mid-season Leaf Area Index (LAI) and tillering ability were identified as weed suppressive traits using path analysis. Differences in weed tolerance were found among varieties. Trade-offs may exist between competitive traits and yield potential which could be optimised by limiting competitive traits later in the season. Selection of competitive traits with high heritability, whilst minimising yield penalties, could be applied in breeding programmes to develop varieties with greater weed competitive ability

Applications of crop competitive ability in winter oats (Avena sativa L.)

Crop competition is a key component of an integrated approach to weed management. Variation in competitive ability and competitive traits have been identified in many other crop species, however little work has been done on oats. Trials were carried out over four years at one organic site with five husked and three naked oat varieties. Mid-season Leaf Area Index (LAI) and tillering ability were identified as weed suppressive traits using path analysis. Differences in weed tolerance were found among varieties. Trade-offs may exist between competitive traits and yield potential which could be optimised by limiting competitive traits later in the season. Selection of competitive traits with high heritability, whilst minimising yield penalties, could be applied in breeding programmes to develop varieties with greater weed competitive ability

Selecting winter wheat lines from a composite cross population

The extremely diverse genetic variation in wheat Composite Cross Populations (CCP) represents a valuable source of breeding material. Such material could be selected as part of a participatory breeding programme with the potential advantage of selecting adaptation targeted for particular environments. For example, selections could be made aimed at producing lines that would thrive under the wide range of management practices conducted as part of organic and low input farming systems. Ears were selected from a CCP mixed stand under organic field conditions in the UK and Hungary. Selected lines were multiplied as single ear rows and 1m2 plots. The best performing five lines from the two selection sites were trialled in Suffolk, UK, in replicated plots including a commercial control variety (Alchemy) and the original population. Alchemy was chosen due to its good disease resistance and consistent performance at the trial site. Assessments included crop and weed cover, foliar and ear diseases, Leaf Area Index (LAI), crop height, as well as grain and straw yield. The first year of trials has been completed with five of the Hungarian selected lines and trials including locally selected lines are on-going. For the first trial year including only the Hungarian selected lines, there were significant differences among varieties (P<0.001) and Alchemy had the highest average yield. Across all trial entries grain yield was correlated negatively with yellow rust infection on the flag leaf at heading (P<0.001) and with reduced green leaf area during grain ripening (P<0.001). In current trials including locally selected lines, some of the selected lines had significantly lower yellow rust infection than the average of the original CCP and of the control variety Alchemy (P<0.001). There was also greater early ground cover (P<0.005) and (LAI) at tillering (P<0.05) in some lines compared to Alchemy and the original population. Crop cover was also correlated negatively with early weed cover (P<0.05). These observations suggest that it is possible to select lines with enhanced resistance to local disease and the ability to compete with weeds at an early stage. However, because average grain yields and percentage protein content are negatively correlated in this study (P<0.01), this trade-off should not be ignored when selecting lines for specific end uses. This can be avoided by developing mixtures of high performing lines with potentially greater stability than pure-line monocultures. Such mixtures may perform better than the original CCP but with the risk of reduced stability over multiple seasons because of their reduced diversity. Acknowledgements: The work reported here is supported by the EU Core Organic II project COBRA

Atmospheric Degradation of Ecologically Important Biogenic Volatiles:Investigating the Ozonolysis of (E)-β-Ocimene, Isomers of α and β-Farnesene, α-Terpinene and 6-Methyl-5-Hepten-2-One, and Their Gas-Phase Products

Biogenic volatile organic compounds (bVOCs), synthesised by plants, are important mediators of ecological interactions that can also undergo a series of reactions in the atmosphere. Ground-level ozone is a secondary pollutant generated through sunlight-driven reactions between nitrogen oxides (NOx) and VOCs. Its levels have increased since the industrial revolution and reactions involving ozone drive many chemical processes in the troposphere. While ozone precursors often originate in urban areas, winds may carry these hundreds of kilometres, causing ozone formation to also occur in less populated rural regions. Under elevated ozone conditions, ozonolysis of bVOCs can result in quantitative and qualitative changes in the gas phase, reducing the concentrations of certain bVOCs and resulting in the formation of other compounds. Such changes can result in disruption of bVOC-mediated behavioural or ecological interactions. Through a series of gas-phase experiments using Gas Chromatography Mass Spectrometry (GC-MS) and Proton Transfer Reaction Mass Spectrometry (PTR-MS), we investigated the products and their yields from the ozonolysis of a range of ubiquitous bVOCs, which were selected because of their importance in mediating ecological interactions such as pollinator and natural enemy attraction and plant-to-plant communication, namely: (E)-β-ocimene, isomers of α and β-farnesene, α-terpinene and 6-methyl-5-hepten-2-one. New products from the ozonolysis of these compounds were identified, and the formation of these compounds is consistent with terpene-ozone oxidation mechanisms. We present the degradation mechanism of our model bVOCs and identify their reaction products. We discuss the potential ecological implications of the degradation of each bVOC and of the formation of reaction products

A review of the factors that influence pesticide residues in pollen and nectar: future research requirements for optimising the estimation of pollinator exposure

In recent years, the impact of Plant Protection Products (PPPs) on insect pollinator decline has stimulated significant amounts of research, as well as political and public interest. PPP residues have been found in various bee-related matrices, resulting in governmental bodies worldwide releasing guidance documents on methods for the assessment of the overall risk of PPPs to different bee species. An essential part of these risk assessments are PPP residues found in pollen and nectar, as they represent a key route of exposure. However, PPP residue values in these matrices exhibit large variations and are not available for many PPPs and crop species combinations, which results in inaccurate estimations and uncertainties in risk evaluation. Additionally, residue studies on pollen and nectar are expensive and practically challenging. An extrapolation between different cropping scenarios and PPPs is not yet justified, as the behaviour of PPPs in pollen and nectar is poorly understood. Therefore, this review aims to contribute to a better knowledge and understanding of the fate of PPP residues in pollen and nectar and to outline knowledge gaps and future research needs. The literature suggests that four primary factors, the crop type, the application method, the physicochemical properties of a compound and the environmental conditions have the greatest influence on PPP residues in pollen and nectar. However, these factors consist of many sub-factors and initial effects may be disguised by different sampling methodologies, impeding their exact characterisation. Moreover, knowledge about these factors is ambiguous and restricted to a few compounds and plant species. We propose that future research should concentrate on identifying relationships and common features amongst various PPP applications and crops, as well as an overall quantification of the described parameters; in order to enable a reliable estimation of PPP residues in pollen, nectar and other bee matrices

The effects of diesel exhaust pollution on floral volatiles and the consequences for honey bee olfaction

There is growing evidence of a substantial decline in pollinators within Europe and North America, most likely caused by multiple factors such as diseases, poor nutrition, habitat loss, insecticides, and environmental pollution. Diesel exhaust could be a contributing factor to this decline, since we found that diesel exhaust rapidly degrades floral volatiles, which honey bees require for flower recognition. In this study, we exposed eight of the most common floral volatiles to diesel exhaust in order to investigate whether it can affect volatile mediated plant-pollinator interaction. Exposure to diesel exhaust altered the blend of common flower volatiles significantly: myrcene was considerably reduced, β-ocimene became undetectable, and β-caryophyllene was transformed into its cis-isomer isocaryophyllene. Proboscis extension response (PER) assays showed that the alterations of the blend reduced the ability of honey bees to recognize it. The chemically reactive nitrogen oxides fraction of diesel exhaust gas was identified as capable of causing degradation of floral volatiles

An online toolbox for cover crops and living mulches

Cover crops and living mulches form an integral component of conservation agriculture promoting soil health and minimising external inputs. The OSCAR Project (Optimising Subsidiary Crop Applications in Rotation) aims to improve practices of conservation agriculture in farming systems across Europe. The principal output of the project is to develop a toolbox to make technical and scientific information publically available to farmers, researchers, and other stakeholders. The continually evolving toolbox is currently available online at www.covercrops.eu and will consist of three facets (1) An interactive user-fed wiki providing information on subsidiary crops species and machinery use with links to published literature. (2) A searchable database on subsidiary crops and technology. This will detail climatic and soil specific plant traits and will form a decision support tool to aid choices of subsidiary crops. (3) A discussion forum will also facilitate the exchange of information between farmers, researchers and stakeholders on conservation agricultural systems across European countries

Evaluating the effects of integrating trees into temperate arable systems on pest control and pollination

Agroforestry systems, which incorporate trees into agricultural land, could contribute to sustainable agricultural intensification as they have been shown to increase land productivity, biodiversity and some regulating ecosystem services. However, the effect of temperate agroforestry systems on pest control and pollination services has not been comprehensively reviewed, despite the importance of these services for sustainable intensification. We review and analyse the available evidence for silvoarable agroforestry systems, following which we propose a predictive framework for future research to explain the observed variation in results, based on ecological theory and evidence from analogous systems. Of the 12 studies included in our meta-analysis of natural enemies and pests, the observed increases in natural enemy abundance (+24%) and decreases in arthropod herbivore/pest abundance (-25%) in silvoarable systems were both significant, but molluscan pests were more abundant in silvoarable systems in the two available studies. Only three studies reported effects on pollinators, but all found higher abundance in silvoarable compared with arable systems. Measures of pest control or pollination service are scarce, but suggest stronger effect sizes. Our framework seeks to establish hypotheses for future research through an interpretation of our findings in the context of the wider literature, including landscape characteristics, silvoarable system design and management, system maturity, trophic interactions and experimental design. Our findings suggest that silvoarable systems can contribute to sustainable intensification by enhancing beneficial invertebrates and suppressing arthropod pests compared with arable, but future research should include measures of pest control and pollination and implications for productivity and economic value