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As agricultural intensification affects global environmental change, a redesign of our food production systems towards practices that replace external inputs with inbuilt ecosystem services is needed. Specifically, human-induced changes to biogeochemical flows of nitrogen (N) cycling exceed the proposed planetary boundaries, highlighting a priority area for reducing nutrient inputs in agricultural production systems. A new understanding of nutrient interactions in the complete agroecosystem will allow us to better predict and mitigate the consequences of anthropogenic environmental changes compared with a reductionist approach. Here, we review for the first time system-level nutrient interactions, particularly N, in perennial horticulture using high-producing kiwifruit and apple crops grown in New Zealand as a basis to identify critical knowledge gaps and prioritize new research. The major points identified are (1) current nutrient guidelines are from the 1980s to the early 2000s and do not take into account substantial production changes since that time; (2) few studies construct complete nutrient budgets of all sources and losses; (3) nutrient loss estimates are generally low relative to those from other agricultural land uses; (4) there is a lack of studies which address nutrient interactions between above- and below-ground food webs in perennial horticultural crops; (5) there is contradictory literature where fertilizer has been found both to increase and to decrease plant chemical signaling and defense mechanisms. New tools are emerging to improve orchard nutrient management, including advances in fertilizer application techniques, new methods to monitor plant and soil nutrients, and utilizing genetic variability to breed cultivars with improved nutrient use efficiency. To reduce adverse nutrient effects on the environment, new research is needed, addressing the relationships between carbon and nutrients and nutrient demands in modern fruit cultivars and growing systems; the nutrient balance for perennial horticultural crops considering all inputs and outputs; and interactions of the above- and below-ground nutrient flows in orchard food webs.

Pathogens which need a vector for their transmission can alter the vectors’ behaviour to favour their spread. We used the electrical penetration graph technique to investigate this hypothesis by using the tomato potato psyllid Bactericera cockerelli infected or not with the plant pathogen Candidatus Liberibacter solanacearum (CLso) on African boxthorn and tomato. Probing was not affected by the host type but there was a significant effect on probing due to the infection status of the psyllid. More psyllids carried out probing activities in the sieve elements when infected with CLso, and more probing activities were observed from CLso-infected psyllids by comparison to the non-infected groups. Specifically, significant increases in salivation, phloem ingestion and number of probes, before and after reaching the sieve elements, were noticed in the infected groups. Furthermore, time elapsed to reach the sieve elements was significantly shortened by 2 h in the infected group. Remaining probing activities in xylem tissues were not different between all psyllid groups. The observed changes in feeding behaviour by pathogen-infected psyllids may well ensure further spread of the pathogen as greater salivation has the potential to increase transmission, highlighting at the same time the important role that crop and non-crop hosts play in disease epidemiology.

This datasheet on Bactericera cockerelli covers Identity, Overview, Distribution, Dispersal, Hosts/Species Affected, Diagnosis, Biology & Ecology, Natural Enemies, Impacts, Uses, Prevention/Control, Further Information.

The increasing diversity of potential biosecurity threats makes their diagnosis a complicated and evolving area, requiring moving beyond traditional taxonomic species identification. New biosecurity diagnostic tools should provide a greater depth of information on threat biology to enable accurate risk assessment for the more efficient and effective deployment of biosecurity resources. Metabolomics is amongst the new approaches being explored for biosecurity diagnostics, where a broad spectrum of metabolites might signify relevant biological characteristics of an intercepted organism. Examples of these characteristics are physiological signatures of age, reproductive status, geographic origin, pathogen status of potential invertebrate vectors, and the distinction between diseases and abiotic plant stress symptoms. This broad-based approach is attractive, where several biological characteristics of an organism can be assessed with a single measurement. However, it can be impractical as several hundred biological replicates of the organism are needed to build a robust model of a species. New approaches such as mass spectral fingerprinting substantially reduce the time taken for metabolomics measurements, and more sophisticated modelling methods aid feasibility. Promising data are emerging for metabolomics and metabolite fingerprinting for potential biosecurity applications. We discuss the possibilities and potential uses for these new tools for post-detection decisions, diagnosis, and biosecurity.

Nonnative plant pests cause billions of dollars in damages. It is critical to prevent or reduce these losses by intervening at various stages of the invasion process, including pathway risk management (to prevent pest arrival), surveillance and eradication (to counter establishment), and management of established pests (to limit damages). Quantifying benefits and costs of these interventions is important to justify and prioritize investments and to inform biosecurity policy. However, approaches for these estimations differ in (1) the assumed relationship between supply, demand, and prices, and (2) the ability to assess different types of direct and indirect costs at invasion stages, for a given arrival or establishment probability. Here we review economic approaches available to estimate benefits and costs of biosecurity interventions to inform the appropriate selection of approaches. In doing so, we complement previous studies and reviews on estimates of damages from invasive species by considering the influence of economic and methodological assumptions. Cost accounting is suitable for rapid decisions, specific impacts, and simple methodological assumptions but fails to account for feedbacks, such as market adjustments, and may overestimate long‐term economic impacts. Partial equilibrium models consider changes in consumer and producer surplus due to pest impacts or interventions and can account for feedbacks in affected sectors but require specialized economic models, comprehensive data sets, and estimates of commodity supply and demand curves. More intensive computable general equilibrium models can account for feedbacks across entire economies, including capital and labor, and linkages among these. The two major considerations in choosing an approach are (1) the goals of the analysis (e.g., consideration of a single pest or intervention with a limited range of impacts vs. multiple interventions, pests or sectors), and (2) the resources available for analysis such as knowledge, budget and time.

BACKGROUND: Management of tomato potato psyllid (TPP; Bactericera cockerelli (Sulc)) predominantly relies on insecticides. However, biological control agents (BCAs) could provide viable alternatives to suppress TPP populations. In this laboratory experiment, we assessed the predatory mite Amblydromalus limonicus (Garman & McGregor) as a BCA of TPP on whole plants of two tomato and two pepper cultivars over a 5‐week period. RESULTS: Plant species and cultivar had a significant effect on the ability of A. limonicus to suppress populations of TPP. Numbers of TPP were suppressed by A. limonicus on four pepper treatments, but on only one tomato treatment. Amblydromalus limonicus could survive and reproduce on pepper and tomato, but more were found on pepper at the end of the 5‐week period. CONCLUSION: Amblydromalus limonicus has the potential to suppress TPP populations on pepper but not tomato cultivars, based on the present study. Possible reasons for these results include the difference in leaf morphology between species, and higher predator:prey ratios on pepper than tomato because of the longer TPP generation time on pepper. © 2018 Society of Chemical Industry

Data from 190 plant pathogen eradication programs in the Global Eradication and Response Database (GERDA) were reviewed to identify characteristics that contributed to successful programs in 45 countries between 1912 and 2013. The most successful treatment (94%) was tissue culture, often in combination with thermotherapy to eradicate viral or bacterial pathogens from plants held in in germplasm collections. Whilst 6% of these programs had no reported outcome, there were no recorded failures of this strategy. Host removal and/or destruction was successful in 55% of the programs and was used against all the pathogen groups. The analysis was limited by the high percentage of unknown outcome results across the pathogen groups. A quarter (49 of 190) of the records contained no indication of the eradication treatment: in 43% of these cases an unknown treatment resulted in successful eradication. There were no obvious correlations between the characteristics of a pathogen (viral/viroid, bacterial/phytoplasma, fungal/oomycete or nematode) and the outcome of the eradication program. For many species there is only one record, or the taxa records were dominated by a few genera that do not represent the biological diversity of the pathogen group. No economic or other analysis was possible due to the large number of unknown result/ongoing programs and the lack of common data. Despite these limitations, GERDA is an important record of the outcomes of worldwide plant pathogen eradication programs since the second decade of the twentieth century. However, care should be exercised when extrapolating from these records to formulating responses to new taxa as pathogens emerge and/or adapt to new plant hosts as the biology of plant pathogens is extremely variable and this diversity is not represented by the records in the database.

Management of tomato potato psyllid (TPP; Bactericera cockerelli (Šulc)) predominantly relies on insecticides. However, biological control agents (BCAs) could provide viable alternatives to suppress TPP populations. In this laboratory experiment, we assessed the predatory mite Amblydromalus limonicus (GarmanMcGregor) as a BCA of TPP on whole plants of two tomato and two pepper cultivars over a 5-week period.Plant species and cultivar had a significant effect on the ability of A. limonicus to suppress populations of TPP. Numbers of TPP were suppressed by A. limonicus on four pepper treatments, but on only one tomato treatment. Amblydromalus limonicus could survive and reproduce on pepper and tomato, but more were found on pepper at the end of the 5-week period.Amblydromalus limonicus has the potential to suppress TPP populations on pepper but not tomato cultivars, based on the present study. Possible reasons for these results include the difference in leaf morphology between species, and higher predator:prey ratios on pepper than tomato because of the longer TPP generation time on pepper. © 2018 Society of Chemical Industry.

Tomato potato psyllid (TPP) Bactericera cockerelli (Scaron;ulc) (Hemiptera Triozidae) was first recorded in the North Island of New Zealand in 2006 Three years later the insect was found in the Oamaru area (South Island) Over the years there has been a rise in TPP numbers trapped in potato crops in Canterbury (South Island) Recently increased prevalence and severity of foliar and tuber symptoms related to plant infection with Candidatus Liberibacter solanacearum (CLso) vectored by TPP have been observed in trials and in commercial potato crops Moreover in the 201314 season the resulting zebra chip disease was observed for the first time in tubers at a processing plant in Canterbury It is concluded that Canterbury has a landscape where hosts are available yearround and a climate that does not seem to hinder TPP development The aim of this paper is to present a stocktake of TPP in Canterbury

Apple Futures was a research implementation project designed to produce export quality, ultra-low residue apples while meeting the phytosanitary requirements of over 60 countries. In 3 years from 2007/08 to 2009/10 seasons it was successfully implemented on 65% of New Zealand's export apple crop with a benefit-cost ratio of 30 times the value of the investment. The process of developing and implementing Apple Futures is the subject of a case study on co-innovation - an approach to solving complex problems that engages multiple stakeholders throughout research and extension initiatives to enhance adoption and impact. A new innovation system analysis framework was used to identify key co-innovation learnings. These included the importance of trust amongst participants, learning together, a clear agenda for change, and monitoring and evaluating progress towards that change agenda. Findings are discussed in the context of maximising impact in innovation projects in New Zealand's primary sector.

Piercing-sucking insects are vectors of plant pathogens, and an understanding of their feeding behaviour is crucial for studies on insect population dynamics and pathogen spread. This study examines probing behaviour of the eggplant psyllid, Acizzia solanicola (Hemiptera: Psyllidae), using the electrical penetration graph (EPG) technique, on two widespread and common hosts: eggplant (Solanum melongena) and tobacco bush (S. mauritianum). Six EPG waveforms were observed: waveform NP (non-probing phase), waveform C (pathway phase), G (feeding activities in xylem tissues), D (first contact with phloem tissues), E1 (salivation in the sieve elements) and E2 (ingestion from phloem tissues). Results showed that A. solanicola is predominantly a phloem feeder and time spent in salivation and ingestion phases (E1 and E2) differed between hosts. Feeding was enhanced on eggplant compared to tobacco bush which showed some degree of resistance, as evidenced by shorter periods of phloem ingestion, a higher propensity to return to the pathway phase once in the sieve elements and higher number of salivation events on tobacco bush. We discuss how prolonged phloem feeding could indicate the potential for A. solanicola to become an important pest of eggplant and potential pathogen vector.

Co-innovation can be effective for complex challenges – involving interactions amongst multiple stakeholders, viewpoints, perceptions, practices and interests across programmes, sectors and national systems. Approaches to challenges in the primary sector have tended to be linear, where tools and outputs are developed by a few, mostly scientists/researchers, and then extended to stakeholders. A co-innovation approach first deciphers and delineates the biophysical, societal, regulatory, policy, economic and environmental drivers, constraints and controls influencing these challenges at multiple levels. Second, stakeholder interactions and perspectives can inform and change the focus as well as help in co-developing solutions to deliver agreed outcomes. However, there is limited systematic and comparative research on how co-innovation works out in different projects. Here we analyse the results of applying a co-innovation approach to five research projects in the New Zealand primary sector. The projects varied in depth and breadth of stakeholder engagement, availability of ready-made solutions and prevalence of interests and conflicts. The projects show how and why co-innovation approaches in some cases contributed to a shared understanding of complex problems. Our results confirm the context specificity of co-innovation practices.

Candidatus Liberibacter solanacearum (CLso) is an unculturable bacterium vectored by the tomato potato psyllid (TPP) Bactericera cockerelli and has been associated with Zebra chip disease in potato and with other economically relevant symptoms observed in solanaceous crops. By altering their host and vector's biological system, pathogens are able to induce changes that benefit them by increasing their transmission rate. Understanding these changes can enable better targeting of mechanisms to control pathogen outbreaks. Here, we explored how the CLso infectious status affects the volatile organic compounds (VOCs) of the tomato plant, and whether the CLso infectious status of TPP influences host plant settlement. These chemical and behavioral changes can ultimately affect the rate of encounter between the host and the vector. Results from headspace volatile collection of tomato plants showed that CLso infected tomato plants emitted a qualitatively and quantitatively different blend of VOCs compared to sham-infected plants. By a factorial experiment, we showed that CLso negative (CLso-) TPP preferred to settle 70 % more often on infected tomato plants, while CLso positive (CLso+) TPP were found 68 % more often on sham-infected tomato plants. These results provide new evidence in favor of both host and vector manipulation by CLso.

Visual cues play a key role in host finding in many phytophagous insects, including the tomato potato psyllid (TPP), Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), a serious pest of solanaceous crops. This study evaluated the response of TPP to sticky traps of one of three colours, up to four sizes, and with or without green borders in an organic potato crop in Hawke's Bay, New Zealand. On average, large traps caught a higher density of TPP than small traps (with or without border; 25 and 14 TPP per 100 cm2, respectively). Tomato potato psyllid density on the green border was affected by the colour of the centre trap; a blue centre resulted in substantially fewer TPP on the green border than a yellow centre (9.0 vs. 69.6 TPP per 100 cm2). Trap catches in early summer were male biased, whereas catches of male and female TPP in late summer were approximately equal.

The tomato potato psyllid, Bactericera cockerelli (Sulc) (TPP), vectors Candidatus Liberibacter solanacearum (CLso), which is the putative causative agent of zebra chip, an important disease of potato. Laboratory bioassays using potted potato plants and CLso- positive TPP were conducted to assess the potential of biorational and selective insecticides to disrupt CLso transmission. The first assay tested eight products, with TPP introduced to plants 24 h after insecticide application and sprayed off after 24 h. The second assay further tested five products and assessed systemic activity, with TPP introduced 24, 72 or 168 h after product application. Stolon samples were collected and analysed for presence of the CLso gene using qPCR. Results have shown potential for biorational and selective insecticides to reduce the quantity of CLso transmitted to plants with varying efficiencies, and although none completely inhibited CLso transmission, there is scope for these products to be included in crop management strategies.

Since its discovery in 2006, the tomato potato psyllid, Bactericera cockerelli (Sulc) (TPP), has been considered a signiicant pest of solanaceous crops in New Zealand, resulting in an intensiication of insect pest control measures, often with the use of broad-spectrum insecticides. In the search for more sustainable control methods in outdoor potato crops, several biorational insecticides were tested in laboratory bioassays to assess their effects on TPP behaviour and mortality. The products tested were Organic JMS Stylet-Oil®, Excel Oil®, Eco-Oil®, Neem 600 WP and Sap Sucker Plus. Given the eficacy of JMS Stylet- Oil®, Sap Sucker Plus and Excel Oil® at reducing TPP numbers and their probing/feeding deterrent qualities, these products are now being tested in a ield trial. The impacts of the tested biorational insecticides on beneicial insects are also being assessed in laboratory and ield trials.

The Argentine stem weevil Listronotus bonariensis Kuschel (Coleoptera: Curculionidae) is an exotic pest of New Zealand ryegrass and the adult-stage is parasitized by the introduced solitary endoparasitoid Microctonus hyperodae Loan (Hymenoptera: Braconidae: Euphorinae). This biological control agent is effective, although, under both laboratory and field conditions, an unexplained source of premature mortality in the weevils is observed after exposure to M. hyperodae. This premature mortality may be affected to varying degrees by the length of time of parasitoid exposure, the physiological conditions of the host, and the host to parasitoid ratios, although it occurs naturally without any physical interruption to the parasitoid ovipositional process. In the present study, the premature mortality reported in earlier studies is confirmed and it is conjectured to be the result of injection of parasitoid venom without an egg. Moreover, the lack of premature mortality resulting from longer exposure periods indicates that there might be a curative effect resulting from subsequent oviposition; the egg reverses the toxic effect induced by the injection of venom only. As discussed, this phenomenon may not be restricted to the L. bonariensis/M. hyperodae system and, accordingly, there are evolutionary, biosecurity and general pest management questions to be considered.

Disease dynamics of Cercospora leaf spot (CLS) of sugar beet was analyzed at two hierarchical scales: as vertical profiles within individual plants and in relation to disease on neighboring plants. The relative contribution of different leaf layers to increase in CLS was analyzed using a simple continuous-time model. The model was fitted to data from two field trials in the Netherlands: one in an area with a long history of CLS, the other in an area where CLS has only recently established; in each case these were unsprayed and twice-sprayed treatments. There were differences in the relative contribution of different leaf layers to disease increase on the target leaf layer according to the CLS history and whether the plants were sprayed or unsprayed. In both field trials, parameter estimates giving the relative contribution of the target leaf layer to disease increase at that leaf layer were higher than those for the lower leaf layer. On only a few occasions the contribution of an upper leaf layer to disease increase at the target leaf layer was significant. Thus, CLS increase at the target leaf layer was determined mainly by disease severity at that leaf layer and to a lesser extent by disease at the lower leaf layer. Our continuous-time model was also used to analyze CLS increase on an individual sugar beet plant in relation to its own and its neighbor's level of disease in field trials at five locations in the two CLS areas over two years. In all field trials, the contribution of the target plant itself to disease increase (auto-infection) was larger than that of its neighboring plants (allo-infection). The overall analysis in the two CLS areas also indicated a larger contribution of the target plant to its disease increase than of neighboring plants, and this pattern was also apparent in a pooled analysis across all sites. Thus, CLS increase on a sugar beet plant was mainly determined by the disease severity on that plant and to a lesser extent by its within-row neighboring plants.

Two approaches to supervised control of Cercospora leaf spot (CLS) in sugar beet are outlined, and their yield improving capabilities tested in field trials. One approach is based on action thresholds, which use disease severity assessments to indicate the need for a fungicide application. The second is based on measurements of within-crop temperature and relative humidity, to indicate the need for a fungicide application. Disease incidence (% diseased plants) in fungicide treated plots increased in a similar way to unsprayed plots. Incidence increased for all treatments before disease severity, assessed using the Agronomica scale, increased. There was little effect of fungicide treatments on model parameters for disease incidence and severity curves. However, fungicide treatments reduced disease severity by up to 50% and resulted in significantly higher relative sugar yields than the unsprayed treatment (set at 100%). Relative sugar yields from applying the action threshold for two early sprays (115%) and for both weather-based treatments (119% and 121%) did not differ significantly from the calendar sprayed treatment (119%), saving up to two fungicide applications. Fungicide treatments based on weather conditions delayed the increase in disease incidence, and were applied 1 week before treatments based on the first action threshold. Considering the significantly higher financial returns in 2001 and the positive experience with the weather-based system in 2003 and 2004, we conclude that sugar beet growers in the Netherlands should move towards using supervised control approaches for CLS in sugar beet although some further testing of the weather-based system will be necessary.

Widespread replacement of native ecosystems by productive land sometimes results in the outbreak of a native species. In New Zealand, the introduction of exotic pastoral plants has resulted in diet alteration of the native coleopteran species,Costelytra zealandica(White) (Scarabaeidae) such that this insect has reached the status of pest. In contrast,C. brunneum(Broun), a congeneric species, has not developed such a relationship with these ‘novel’ host plants. This study investigated the feeding preferences and fitness performance of these two closely related scarab beetles to increase fundamental knowledge about the mechanisms responsible for the development of invasive characteristics in native insects. To this end, the feeding preference of third instar larvae of bothCostelytraspecies was investigated using an olfactometer device, and the survival and larval growth of the invasive speciesC. zealandicawere compared on native and exotic host plants.Costelytra zealandica, when sampled from exotic pastures, was unable to fully utilise its ancestral native host and showed higher feeding preference and performance on exotic plants. In contrast,C. zealandicasampled from native grasslands did not perform significantly better on either host and showed similar feeding preferences toC. brunneum, which exhibited no feeding preference. This study suggests the possibility of strong intraspecific variation in the ability ofC. zealandicato exploit native or exotic plants, supporting the hypothesis that such ability underpins the existence of distinct host-races in this species.

Widespread replacement of native ecosystems by productive land sometimes results in the outbreak of a native species. In New Zealand, the introduction of exotic pastoral plants has resulted in the diet alteration of the native coleopteran species, Costelytra zealandica (White) (Scarabaeidae) such that this insect has reached the status of pest. In contrast, C. brunneum (Broun), a close congeneric species, has not developed such a relationship with these ‘new’ host plants. This study investigated the feeding preferences and fitness performance of these two closely related scarab beetles to increase fundamental knowledge about the mechanisms responsible for the development of invasive characteristics in native insects. To this end the feeding preferences of larvae of both Costelytra species were investigated under controlled conditions and the survival and larval growth of the invasive species C. zealandica were compared on native and exotic host plants. Costelytra zealandica, when sampled from exotic pastures, was unable to fully utilise its ancestral native host and showed better performance on exotic plants. In contrast, C. zealandica sampled from native grasslands did not perform significantly better on either host and showed similar feeding preferences to C. brunneum. This study suggests the possibility of strong intra-specific variation, in the ability of C. zealandica to exploit native or exotic plants, supporting the hypothesis that such ability underpins the existence of distinct host-races in this species.

Spatial disease pattern of Cercospora beticola was characterised during natural epidemics of Cercospora leaf spot (CLS) in sugar beet. We applied linear regression and geostatistical analyses to characterise CLS spatial patterns in three field trials, in long-established and recently-established CLS-areas, during two consecutive years. Linear regression showed a positive influence of average disease severity of within-row neighbouring plants (0.38 < \(\hat \beta_1 \) < 0.88). Semi-variograms modelled the spatial dependence of disease severity for two directions per week in both years. Disease severity displayed strong spatial dependence over time. The within-row spatial dependence was the largest, but across-row dependence was irregular and weaker. Both long- and recently established areas showed strong spatial dependence of disease severity within row, decrease in variability between years and within the second trial year and a relation between \(\hat \beta _1 \) and the relative nugget. Observed differences were more field than area specific. These spatial and temporal analyses indicated that disease severities of adjacent plants were dependent; hence, we concluded that C. beticola is dispersed mainly over short distances from plant to plant.

Sugar beet root infection by Cercospora beticola, the causal agent of Cercospora leaf spot (CLS), was studied in a climate chamber and in the field. In the climate chamber, root incubation of susceptible seedlings with a conidial suspension resulted in disease incidences that were significantly different for two sugar beet cultivars (Auris: 0.8 ± 0.14 and A00170: 0.5 ± 0.18; P 95) in our climate chamber or after canopy closure in the field. Quantification of root infection and long term survival in soil is necessary to assess its contribution to the epidemiology and life cycle of Cercospora beticola. Cultural methods such as a wider crop rotation, management of crop debris and ploughing systems may provide control strategies alternative to or reducing fungicide input.

Two disease severity scales for Cercospora leaf spot (CLS) assessment were compared. CLS was assessed in two experimental fields in the Netherlands in 1999 using two scales: a single leaf severity assessment, as used in the IPS-system (Integriertes Pflanzenschutzsystem) in Germany, referred to as DS IPS , and a whole plant assessment, Agronomica diagram from Italy, referred to as DS AGR . To obtain a range of disease severities, fungicides were applied at defined action thresholds based on disease incidence and severity. There was an exponential relationship between DS IPS and DS AGR ( R 2 =86%) for pooled data with little change in the whole plant assessment above DS IPS =5%. An exponential curve best fitted DS IPS and root and sugar weight in fields severely infected with CLS, whereas a linear curve was found for mildly infected fields. A linear curve fitted DS AGR best with root and sugar weight in both severely and mildly infected fields. No relationship was found between both DS IPS and DS AGR and sugar content. The use of DS AGR was less time consuming in monitoring and was done with greater accuracy, efficiency and level of reproducibility than DS IPS . These results demonstrate that CLS assessment can be less time-consuming and more practical in application.

Since its 2006 detection in New Zealand, the tomato potato psyllid (TPP), Bactericera cockerelli, has been responsible for yield and quality-reducing damage to potatoes as well as to other solanaceous crops. TPP is best known as the insect vector for the zebra chip disease-associated bacterium Candidatus Liberibacter solanacearum (CLso), but feeding by CLso-negative TPP on potatoes is also linked to damaging effects. An improved understanding of which potato plant physiological stages are most affected by feeding of CLso-negative TPP will allow for more directed integrated pest management (IPM) plans. As part of a two-year repeated eld study to assess the effect of TPP feeding timing on potatoes, CLso-negative TPP were released into mesh cages over outdoor potato (‘Moonlight’) plantings at ve different growth stages: post-emergence, owering, post- owering, late-season, and pre-harvest. Tubers were grouped by plant at harvest. (Un)marketable numbers and weights, marketable dry matter and zebra chip severity were determined. Results from this trial and other shadehouse trials conducted previously are still being analysed but have the potential to better target IPM plans and reduce costly, labour-intensive, and environmentally impactful pesticide spray use, which is currently relied on heavily throughout growing seasons.

A simple, inexpensive chamber was developed and tested as an evaluative tool to monitor Trichogramma cordubensis dispersal in the laboratory. The chamber consisted of a continuous, winding channel which was cut into an aluminum block. Wasps were released at one end of the channel and allowed to walk in the channel for 21 h and to parasitize Mamestra brassicae eggs placed 3.4 m from the point of wasp introduction. Comparisons between two T. cordubensis populations demonstrated that one population (TCM) dispersed more in the chamber and located host eggs more successfully than the other population (TCD). Subsequent greenhouse releases confirmed that the TCM population dispersed more readily and had significantly higher parasitism rates on sentinel Ephestia kuehniella eggs on tomato plants. The potential utilization of this chamber as a tool to evaluate quality of Trichogramma populations, mainly dispersal activity, is discussed.

Tomato potato psyllid (TPP), Bactericera cockerelli , is a vector of the bacterium ' Candidatus Liberibacter solanacearum' (CLso). The pathogen and insect severely impact solanaceous crops in the USA, Central America and New Zealand…

The tomato potato psyllid, Bactericera cockerelli (TPP), and the bacterium it vectors, Candidatus Liberibacter solanacearum (CLso), are collectively responsible for significant economic losses across New Zealand’s horticulture industry. Crop host plants of TPP include potatoes, tomatoes, capsicums/ chilli peppers, tamarillos and tobacco, along with less-obvious species outside the Solanaceae family, such as kumara (Convolvulaceae). Most of these plants are short-lived summer annuals, which raises the question: what happens to TPP when crops are absent? Many less conspicuous non-crop plants also play host to TPP, some of which are perennial and therefore present year-round, potentially acting as reservoirs of both TPP and CLso in the absence of a crop. A pilot study in 2012 and subsequent vegetation surveys in Canterbury and Hawke’s Bay in 2013-14 confirmed the presence of all TPP life stages on multiple non-crop species year-round in both areas, despite adverse climatic events such as winter frosts and snowfall. These results have far-reaching impacts on the way growers should manage the borders surrounding their crops and their land in the off-season.

Op 15 juni 2004 promoveerde Jessica Vereijssen aan Wageningen Universiteit op haar proefschrift getiteld: 'Cercospora leaf spot in sugar beet: Epidemiology, life cycle components and disease management'. De promotor was prof. dr. MJ Jeger en co-promotoren waren dr. ir. JHM Schneider (IRS (Instituut voor Rationele Suikerproduktie)) en dr. ir. AJ Termorshuizen (Biologische Bedrijfssystemen, WU)

A potential primary infection site of the foliar pathogen Cercospora beticola in sugar beet is described. Sugar beet seedlings of the susceptible cv. Auris were grown in a standard soil for 14 days. A monoconidial culture of a C. beticola isolate was grown to produce conidia. In experiment 1, roots were immersed in a conidial suspension of isolate code IRS 00-4, or in tap water (control), for 2 days. After incubation seedlings were potted in a peat – fine river sand mixture and placed at low relative humidity (RH) (

The tomato potato psyllid (TPP), Bactericera cockerelli, invaded New Zealand in 2006 and has now spread throughout most of the country. TPP is an economically important pest of solanaceous crops that that not only causes damage through its feeding but also transmits the bacterium Candidatus Liberibacter solanacearum, which is associated with zebra chip disease in potato. Published developmental thresholds, meteorological data, and potato emergence and harvesting dates were used to estimate the potential number of generations of TPP for the main potato-growing regions in cold, average and hot spring and summer seasons in the 20062013 period. Temperature was highly variable in spring and summer between regions and between years within a region. The main effect of higher temperatures was that TPP generations were completed earlier, which resulted in up to one extra generation in a season. In the North Island regions, spring temperatures were such that up to two generations could develop before potato emergence, in contrast to the South Island, where less than one generation occurred during this time. This information can be used by crop managers to target management interventions for TPP more effectively.

The braconid endoparasitoid Microctonus hyperodae was successfully introduced into New Zealand in 1991 to control the exotic pastoral pest Argentine stem weevil (ASW) The wasp parasitises adult ASW and the weevil normally dies only when the fifthinstar parasitoid larva emerges However during biocontrol research over the last 20 years premature mortality of ASW has been observed under conditions of high parasitoid pressure in the field and laboratory It was hypothesised that this occurs because of injection of venom without an egg To conclude absence of a parasitoid egg in a prematurely dead weevil a sensitive method is needed to detect a newly oviposited parasitoid egg However this cannot be confirmed by visual observation or by dissection because fresh tissue is subsequently needed to detect venom A molecular method was therefore developed Firstly to model oviposition eggs were dissected from the ovaries of an adult parasitoid and one ovarian parasitoid egg was used to spike ASWs that had been dissected to confirm absence of parasitism Secondly multiplexPCR was successful in detecting a single ovarian egg in ASW This result greatly benefits research into the observed premature mortality of ASW after being exposed to M hyperodae

Co-innovation can be effective for addressing complex challenges involving multiple stakeholders who hold diverse viewpoints and perceptions. Addressing these challenges requires changes at various scales. However, there is limited systematic research on how co-innovation can work in different projects and what impacts it can have on the outcome. Co-innovation principles were tested for their potential to enhance the impact delivered by a fundamental research project investigating options for managing the tomato potato psyllid/Candidatus Liberibacter solanacearum complex in potato crops. A series of interviews and workshops were undertaken to increase interactions within the programme and with industry stakeholders. Additionally, a member of the research team, trained in co-innovation theory and practice, took a leadership role in planning and delivering technology transfer activities. The effects of bringing co-innovation principles to the programme are described, in particular the challenges encountered when introducing these concepts into a fundamental research programme.

Cercospora beticola, the causal agent of Cercospora 1eaf spot (CLS) in sugar beet, causes I reductions in sugar yield and financial returns. Section I describes the epidemiology of CLS. Two disease severity indices were compared and their relation with sugar yield modelled. A linear curve fitted the Agronomica disease severity index with sugar yield in both severely and mildIy infected fields, whereas for a 1eaf disease severity assessment this relationship was exponential and linear, respectively. The Agronomica disease severity index was less laborious and improved disease assessment. Using spatial and temporal rnodels, the within-row dependencies of CLS disease severities was demonstrated. However, disease increase on a given plant was largely determined b>disease on that plant. Similarly when describing the within-plant dynamics of disease, i1 was concluded that the major determinant of disease increase on a given 1eaf layer on ? plant was from disease on that 1eaf layer. Spraying a fungicide twice changed the contribution of the lower 1eaf layers. In one mildly infected field, these 1eaf layers were more often significant in the model; in the other severely infected field less often. Ir section II studies on the life cycle of CLS are reported. It was demonstrated that C beticola is able to infect sugar beet through the root in glasshouse, climate room, and ir field experiments. The genetic variability of C. beticola was studied in an international collection of isolates. Between and within geographic regions, genetic variability is high A C. beticola specific PCR primer was developed, which enabled detection of C. beticolc in plant tissue, We showed systemic growth of C. beticola in a sugar beet seedling after root infection. Section III describes the development of a supervised control system. The use of an action threshold involving two early sprays and weather-based treatment: resulted in sugar yields and financial returns similar to calendar sprayed treatments, am saved up to two fungicide applications.