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IOBC-WPRS Bulletin Vol. 104, 2014

 

IOBC-WPRS Bulletin Vol. 104, 2014

Working Group "Integrated Control in Oilseed Crops".
Proceedings of the meeting at the Centre de Recherche Public - Gabriel Lippmann, Belvaux, Luxembourg, 8th - 10th October, 2013.
Edited by Birger Koopmann, Samantha Cook, Neal Evans and Michael Eickermann.
ISBN 978-92-9067-285-2 [XV + 176 pp.]

 

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Current diseases of winter oilseed rape worldwide and their control
Malgorzata Jedryczka

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3

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Impact of regional climate change on pest insects in oilseed rape
Michael Eickermann, Lucien Hoffmann and Jürgen Junk

Abstract: Global and regional climate models are suitable tools to simulate the future climate. However, climate change projections are afflicted with different uncertainties, e.g. due to an incomplete coverage of all physical processes involved. A possible way to deal with these uncertainties related to model results is to analyze an ensemble of equally valid, possible realizations of regional climate model projections. Furthermore, the use of an ensemble of future climate projections leads to more accurate estimates of the potential future changes, because the effect of the internal variability can be more accurately addressed. Examples of multi model ensemble approaches in agriculture are discussed in the literature. Aside from effects on agricultural practice, possible impacts of global climate change are also expected on pest species in crop production, e.g. species distribution or shifting of crop invasion. Since 2009, an expert group of meteorologists, entomologists and modellers has been investigating the effect of regional climate change on pest species in oilseed crops for Luxembourg within the framework of several research projects. So far, projections have been done for the rape stem weevil, Ceutorhynchus napi (Gyll.), the cabbage stem weevil, Ceutorhynchus pallidactylus (Mrsh.) and the pod midge, Dasineura brassicae (Winn.). Based on an ensemble of 6 regional climate change projections, the bandwidths of possible change signals and the uncertainty associated with these projections were investigated for the near (2021 - 2050) and far future (2069 - 2098) in comparison to a reference time period (1961 - 1990). All projections were based on the Special Report on Emissions (SRES) A1B emission scenario of the Intergovernmental Panel on Climate Change (IPCC). This scenario describes anthropogenic emissions of a future world with rapid economic growth, an increasing global population until the middle of this century and a balanced use of fossil and non-fossil energy resources.

5-9

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Quantification of ecological services for sustainable agriculture
John Holland, Philippe Jeanneret, Wopke van der Werf, Anna-Camilla Moonen, Jozsef Kiss, Maarten van Helden, Maria Luisa Paracchini, James Cresswell, Philippe Pointereau, Bart Heijne, Eve Veromann, Daniele Antichi, Martin Entling and Bálint Balázs

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10

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Oilseed crops in the Czech Republic and their health state in 2013
Jana Poslušná and Eva Plachká

Abstract: In the Czech Republic the following crops are grown as oilseeds: winter oilseed rape (Brassica napus), white mustard (Sinapis alba), sunflower (Helianthus annuus), poppy (Papaver somniferum), brown mustard (Brassica juncea), oilseed flax (Linum usitatissimum), and on a small area soybean (Glycine soja) and peanut pumpkins (Cucurbita oleifera). Areas of oilseeds increase every year particularly the proportion of winter oilseed rape. This year's rapeseed area reached 401.3 thousand hectares. Among the most important fungal diseases of oilseeds are Phoma stem canker (Phoma lingam) and white rot of oilseed rape (Sclerotinia sclerotiorum). Among the important pests of oilseeds are stem and pod weevils (Ceutorhynchus spp.), pollen beetle (Meligethes aeneus) and Brassica pod midge (Dasyneura brassicae). The second most important oil plant in the Czech Republic is sunflower with 24.6 thousand hectares grown in 2013. The most significant diseases and pests of sunflower include gray mold (Botrytis cinerea), sunflower white rot (Sclerotinia sclerotiorum) and aphids (Brachycaudus helichrysi and Aphis fabae). Poppy takes third place of the most commonly grown oilseeds with 18.36 thousand hectares grown in 2013. Downey mildew (Peronospora arborescens), leaf blight (Pleospora papaveracea and Dendryphion penicillatum) and occasionally gray mold (Botrytis cinerea) have been reported as problems. Mustard was cultivated in the Czech Republic at 16.94 thousand ha. Among the major diseases of white mustard include white rot (Sclerotinia sclerotiorum), Alternaria leaf spot of Brassica (Alternaria spp.) and gray mold of crucifers (Botrytis cinerea).

11-15

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Spatial distribution of root maggot larvae (Delia radicum) and club-root symptomatic plants (Plasmodiophora brassicae) in winter oilseed rape
Marek Seidenglanz and Vojtěch Hlavjenka

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17-18

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Effects of different soil cultivation after oilseed rape
on the increase of Plasmodiophora brassica and Delia radicum

Simone Dohms, Nazanin Zamani-Noor and Holger Kreye

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19

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The expanding oilseed rape insect pest community in Estonia
Gabriella Kovács, Riina Kaasik, Anne Luik and Eve Veromann

Abstract: The increase in oilseed rape cultivation over the last two decades has led to the introduction of a “new” pest to Estonian farmers. The brassica pod midge, Dasineura brassicae (Winnertz, Diptera: Cecidomyiidae) is a pest of potential economic importance in Europe. Its presence in oilseed rape fields in Estonia became clear during a study conducted to measure the number of overwintered oilseed rape pests and hymenopteran parasitoids within fields and in field edges. Soil samples were collected and incubated in emergence traps from different fields that grew winter oilseed rape in the previous year in Tartu County. Only a low number of pests emerged from these samples from which we can assume that despite the widespread opinion amongst Estonian farmers, most pests do not stay in or near the fields for overwintering. However, the most abundant pest collected was the brassica pod midge, indicating that it does prefer to stay in or near the fields for winter. Additionally, significantly more parasitoids emerged than pests indicating that these natural enemies also chose their overwintering sites within or near the fields. Hence, minimal tillage and a well-planned, diverse crop rotation of at least five years should be favoured to lower the threat of this relatively new pest.

25-28

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Early plant injury as an indicator of infestation level of the cabbage stem flea beetle?
Helle Mathiasen, Peter Esbjerg and Jens Bligaard

Abstract: Forecasting abundance of the cabbage stem flea beetle, Psylliodes chrysocephala, is widely based on monitoring of adult beetles with yellow water traps but there is not always a direct correlation between trap catches and larval density. The objective of this study was to investigate assessment of early plant injury as a monitoring method. This was done in a field cage experiment, by testing the relationship between beetle density and immediate and subsequent plant injury from adults feeding on plants and from larvae mining plant stems. Overall feeding of adults was low. A statistically significant relationship between beetle density and plant injury was not found when plant injury was expressed as damaged plants nor feeding holes. However the experiment revealed a small but significant increase in the number of damaged leaves: 3.3% per beetle at increasing density of beetles. The observed mean number of damaged leaves per cage of 24 plants was 11.6, 13.8, 13.2 and 19.0 at 2, 4, 8 and 16 beetles, respectively, four weeks after the beetles were released into the cages at plant growth stage BBCH 18. There was a statistically significant relationship between beetle density and larval density per plant. The larval density was low and the observed mean numbers of larvae per plant were 0.15, 0.38, 0.87 and 1.42 at 2, 4, 8 and 16 beetles. Overall the present study demonstrates a correlation between adult beetle density and subsequent number of larvae per plant. However, early plant injury was not a satisfactory indicator of infestation level. The possible causes of low levels of feeding and larval density per plant are discussed.

31-37

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Challenges and potential for organic rapeseed production in Denmark
Lars Egelund Olsen, Kathrine Hauge Madsen, Lene Sigsgaard and Jørgen Eilenberg

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39-40

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Parasitism of cabbage stem flea beetle in oilseed rape and turnip rape
Alexander Döring, Dorothea Mennerich and Bernd Ulber

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41

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Field monitoring of cabbage stem flea beetle and rape winter stem weevil autumn flights
Céline Robert

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42

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Population dynamics and sex ratio of adult forms of stem mining weevils in Croatia
Ivan Juran, Tanja Gotlin Čuljak and Dinka Grubišić

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45

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Effects of various resyntheses, lines, and cultivars of oilseed rape on rape stem weevil (Ceutorhynchus napi Gyll.) infestation
Heike L. Schäfer-Kösterke and Bernd Ulber

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46

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Screening of Brassica napus, Sinapis alba and intergeneric hybrids for resistance to cabbage root fly (Delia radicum L.)
Henrike Hennies and Bernd Ulber

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49

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A study to assess the parasitism of insect pests in winter oilseed rape in Belgium: preliminary results
Jean-Pierre Jansen and Sandrine Chavalle

Abstract: A survey of the parasitoids found in commercial winter oilseed rape was initiated in 2012 and 2013 in the South part of Belgium, using both aerial sampling techniques and soil analysis. Fourteen fields located in two distinct areas and with two different tillage regime (normal and reduced or no tillage) were selected for before and just after flowering. Adult parasitoid hymenoptera were weekly sampled over 8 weeks using sweep net. Pollen beetle larvae, Meligethes aeneus (F.) (Col.; Nitidulidae), were collected and their parasitism rate assessed. Samples of soil were taken from 4 fields in 2012 and 8 in 2013 to collect brassica pod midge cocoon, Dasineura brassicae (Winnertz) (Dip.; Cecidomyiidae), and to assess their parasitism. The soils were gently washed into sieves and cocoons were isolated in Petri dishes until midge or parasitoid emergence.
The main parasitoid wasps found in the sweep net samples belong to the Tersilochinae family. However, though adults of this family were regularly collected in large numbers, and were synchronized with their host, the parasitism level of the pollen beetle larvae remained low, with many of the fields below 10-15% parasitism. Preliminary analysis shows that there were no apparent differences between the two distinct areas and between the two different tillage regimes. The main explanation of this low parasitism rate could be the high occurrence of the insecticide applications, as most of the farmers regularly applied one or two insecticides during the season: the first to control pollen beetle before flowering and the second to control other insects later (e.g. seed weevil, brassica pod midge). The highest level of parasitism of pollen beetle larvae (43%) was found in an untreated field. The identification of the species is in progress.
The analysis of brassica pod midge cocoons showed that the parasitism rate was low in 2012 (0-5%). However, these results were probably underestimated due to a high mortality of the cocoons during the rearing process. If the parasitism rates were expressed on the basis of rearing success (brassica pod midge or adult parasitoid emerged), the parasitism rate reached up to 59.6% in one specific site, with 58.8% due to 4 Ceraphronidae species and 48.6% due to one species, Ceraphron serraticornis Kieffer. In 2013, the parasitism rate was low (0-3.0%), despite a high success in the cocoon rearing process.
These results have shown that several species of parasitoid Hymenoptera are present in Belgium, causing in some cases high parasitism levels. A better use of these parasitoid wasps in the biological or integrated control of several oilseed rape pests is possible, but there is a need to focus on improving understanding of the factors that could explain the variability of the parasitism between sites and the actions that could promote the activity of these beneficial insects and protect their existing populations.

53-59

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Pyrethroid resistance of oilseed rape pest insects in Germany
Udo Heimbach and Meike Brandes

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61

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Effect of two different insecticides on the reproduction of pollen beetles in field tests
Meike Brandes, Udo Heimbach, Gerrit Hogrefe and Bernd Ulber

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62

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A study under semi-field conditions on the efficacy of insecticides against Meligethes aeneus F. – Methodical approach and analysis
Caroline Kaiser, Inga Bormann, Martin Ahlemann, Klemens Thierbach, Robert Engelmann, Loreen Schanze, Christa Volkmar, Beate Müller and Joachim Spilke

Abstract: Oilseed rape (Brassica napus L.) is one of the most important oilseed crops in the world. One of the major pests is the pollen beetle (Meligethes aeneus F.) (Nitidulidae). Under certain conditions the beetle can cause yield losses of up to 100%. One contributing factor is the decreased sensitivity to pyrethroid insecticides which has been reported from several European countries. There are two methods for insecticide susceptibility tests: insecticides can be tested in field trials or in the laboratory using the ‘glass vial testing method’. The presented approach is a semi-field method coming with precise statements of the reactions of the beetles to insecticides under realistic field conditions. The method is implemented to study the efficacy of insecticides with different mode of actions. Pollen beetle populations were collected from untreated fields in Saxony-Anhalt, Germany. Six insecticides with different mode of actions were sprayed in the field. Treated plants were cut and brought into the greenhouse on nine sampling occasions. Each plant was placed into a perforated plastic bag with 10 beetles. The vitality of the beetles was observed after two and five days following inoculation. To describe the efficacy of insecticides the beetles were divided into three categories (alive, damaged and dead). These observations were interpreted as a realization of classified ordered categorical random variables. For the analysis we used a threshold model (generalized linear model). The dependence of the observations due to repeated observations on the same plant was accounted for by a random plant effect. The comparison of the different insecticides and their significance test was made by using the marginal expectation values. For the computational implementation, we used the procedure NL MIXED (SAS 9.3).

63-66

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A large field trial to assess the short-term and long-term effects of 4 insecticides used to control the pollen beetle on parasitic hymenoptera in oilseed rape
Jean-Pierre Jansen and Gilles San Martin Y Gomez

Abstract: A large-scale field trial was performed in spring 2013 to assess the effects of Plenum (pymetrozine), Mavrik 2F (tau-fluvalinate), Biscaya (thiacloprid) and Pyrinex (Chlorpyriphos-ethyl) used to control the pollen beetle Meligethes aeneus (F.) (Col.; Nitidulidae) on the populations of pests and beneficial arthropods in winter oilseed rape. The insecticides were applied at their commercial rate just before flowering on large strips of oilseed rape (30 m x 200 m), divided into four plots of 50 m x 30 m. A strip was left untreated as control. Insects were sampled by plant beating methods and sweep netting the day after treatment and thereafter weekly up to 50 days after product application. The direct effects of the products were assessed on adult pollen beetle (target pest), adult cabbage seed weevil Ceutorrhynchus obstrictus (Marsham) (Col.; Curculionidae) (secondary pest) and adult parasitic hymenoptera associated with these insects (Tersilochinae and Pteromalidae). In the context of IPM, long term effects were assessed on pollen beetle larvae to determine their number, the parasitism rate and to estimate the balance of parasitic hymenoptera/pollen beetle that could be produced by the field for the next season.
Biscaya, Pyrinex and Mavrik 2F were effective in controlling the adult pollen beetle population and also had activity on cabbage seed weevil, despite the fact that this pest only occurred 2 or 3 weeks after the application of product. Plenum was only effective in controlling the pollen beetle population 1 day after treatment and had no significant impact on cabbage seed weevil.
All the insecticides tested had a significant impact on the population of adult parasitic hymenoptera compared to the control. Plenum had limited effects while the other insecticides reduced by 59-72% the numbers captured in the sweep net samples. The main effects were observed on adults of the Tersilochinae family that are mainly specialised in the parasitism of pollen beetle larvae. Biscaya also had a significant impact on numbers of Pteromalidae caught, a family containing species specialised in the parasitism of weevils, despite the 4-week delay between the day of the treatments and the first arrival of these hymenoptera in the crop.
Biscaya significantly reduced the parasitism rate of the pollen beetle larvae, which was reduced to less than 15% compared to 43.2% in the control. Pyrinex also decreased the parasitism rate with only 23% larval parasitism, but the difference was not significant. Biscaya and, to a lesser extend Pyrinex, reduced the balance of parasitic hymenoptera: pollen beetle, while Plenum and Mavrik 2F led to the same ratio as the untreated control. These results suggest that the regular use of Biscaya and/or Pyrinex on a large scale before flowering is favourable to the long term development of pollen beetle populations by negatively impacting the populations of their parasitoids, despite their good short-term efficacy to control this pest.

67-74

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Parasitism of pollen beetle, Meligethes aeneus F., in different regions of Northern Germany
Helge Stahlmann and Bernd Ulber

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75

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Olfactometer screening of repellent essential oils against the pollen beetle (Meligethes spp.)
Claudia Daniel

Abstract: Essential oils can have an impact on pollen beetle (Meligethes spp.) host plant location behaviour. Lavender oil (Lavendula angustifolia) showed the highest repellency value in a previous laboratory study that compared five different essential oils (Mauchline et al., 2005). However, lavender oil is one of the most expensive essential oils – a fact that could seriously hamper on-farm implementation of this strategy. To find a cheaper essential oil with comparable efficacy to lavender oil, we compared the essential oils of Mentha arvensis, Eucalyptus globulus, Melaleuca alternifolia, Citrus sinensis, Citrus paradisi, Citrus limon, Juniperus mexicana, Abies sibirica, Illicium verum, Gaultheria procumbens, Cymbopogon flexuosus, Syzygium aromaticum, and Litsea cubeba using a Y-tube-olfactometer. Essential oils were diluted 1:10 in acetone and 40 μl was applied to a 3.1 cm-diameter filter paper. Filter papers were placed in the odour containers of the olfactometer together with a flower cluster of spring oilseed rape with 5 open flowers and 10-15 buds. The control treatment involved filter papers treated only with acetone. Hungry pollen beetles were released individually into the olfactometer. The beetles’ choices were recorded. Flowers and essential oils were changed between replicates. Six replicates with six beetles each were conducted. Highest repellency values were obtained for Mentha arvensis, Cymbopogon flexuosus, and Litsea cubeba.

79-83

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Differential rates of attack of oilseed rape genotypes by the pollen beetle: the cues may be in the bud wall
Maxime Hervé, Nathalie Marnet, Mélanie Leclair, Régine Delourme and Anne Marie Cortesero

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84

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The impact of semi-natural habitats on the abundance of pollen beetle adults on winter oilseed rape fields
Riina Kaasik, Gabriella Kovács, Janne Mölder, Kaia Treier, Liis Vaino and Eve Veromann

Abstract: Pollen beetle dispersal in the field depends on several different factors, such as the phenological stage of the crop, its odour and yellow colour during flowering are especially attractive to pollen beetles. The dispersal of the scent depends on wind direction and pollen beetles’ dispersal follows upwind anemotaxis.
This experiment was conducted to investigate the effect of different semi-natural habitats (woody linear, woody areal, herbaceous linear and herbaceous areal) surrounding winter oilseed rape fields on the abundance of the pollen beetle. Beetles were counted from oilseed rape plants using the beating method. The results showed higher number of pollen beetles on fields bordered with herbaceous linear elements than with other studied semi-natural habitat elements.

85-89

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Flight of Meligethes aeneus at a range of altitudes
Alice Mauchline, Sam M. Cook, Wilf Powell, Jason Chapman and Juliet Osborne

Abstract: The pollen beetle, Meligethes aeneus, is a significant pest of oilseed rape crops and there is considerable research effort focused on developing novel, sustainable methods of integrated control. These insects rely on flight for all dispersal movements and we have investigated their flight patterns using a novel combination of data from suction traps, vertical-looking radar and field counts. Analysis of these preliminary data will help determine the best timing for different control measures within an integrated pest management strategy.

91-95

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Developing and integrated pest management strategy for pollen beetles in oilseed rape: Results from the Defra SA-LINK project LK09108
Sam M. Cook, Andrew W. Ferguson, Matthew P. Skellern, Nigel P. Watts, Janet L. Martin, Lesley E. Smart, Christine M. Woodcock and John A. Pickett

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96

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Results of a small survey amongst farmers and advisers in the UK on their evaluation of the proPlant pollen beetle migration tool and its influence on their practice
Andrew W. Ferguson and Sam M. Cook

Abstract: One of the major impediments to the use of action thresholds for pollen beetle control in oilseed rape has been that proper field monitoring of beetle populations is time consuming and is potentially required over a prolonged period. proPlant Expert is a decision support system (DSS) that uses phenological models parameterised by local meteorological data to forecast pest risks. It is able to forecast the start and end of pollen beetle immigration into the crop and to advise of the main risk periods and when to monitor. The proPlant expert.map pollen beetle migration forecasting tool was made publicly available in the UK on the Bayer CropScience website in spring 2012, encouraged by the success of trials by Rothamsted. Three forecasting maps were provided each day with a traffic light warning system indicating: (1) the risk of migration starting (2) the risk of new migration (3) percent completion of migration. We conducted a small impact survey in spring 2012 to obtain feedback from users of the forecasting tool to support future improvements and delivery of the tool and thereby to encourage uptake. The survey consisted of a one page multiple-choice questionnaire with 17 questions grouped under five headings.
Eighteen farmers and agronomists responded to the call for survey participants. Of these, 10 completed the survey. In this small survey there was overwhelmingly positive feedback. There was clear endorsement of the manner in which the pollen beetle risk forecasting tool was presented and explained. Most users found the tool informative and all found it helpful. Feedback indicated that users were making intelligent use of proPlant expert.map in the context of their experience in the field, as intended. Respondents found that the forecasts corresponded with events in the field and reported that the tool increased their confidence in decision-making, giving them peace of mind. Moreover, using proPlant expert.map reduced eight out of ten users’ estimation of pollen beetle risk and seven believed they had used fewer sprays for pollen beetle control as a result. Eight out of the ten respondents said they would certainly recommend proPlant expert.map to a friend.

97-104

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Global warming and oilseed rape pathogens: potential impacts and adaptation strategies in Northern Germany
Magdalena Siebold and Andreas von Tiedemann

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107

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Field inoculations of winter oilseed rape
Eva Plachká, Jana Poslušná and Ivana Macháčková

Abstract: The aim of our work was to increase the explanatory power of field tests on the health of oilseed rape. We worked with sclerotia of the pathogen Sclerotinia sclerotiorum and conidiospores of Phoma lingam. Pathogen isolates were obtained by collecting tissues of infected plants and isolating the pathogen from infected tissue. Sclerotia were applied to the soil at concentration of 1.5 sclerotia per 1 m2 when sowing oilseed rape. Conidiospores were applied by foliar spray at concentration 20×109 per 1 ha in autumn and in spring. Monitoring was carried out on three varieties of winter oilseed rape with different resistance level to monitor the pathogens. Field trials were established in years 2011/2012 and 2012/2013 at two locations in the Czech Republic – in Opava and Šumperk. The results confirmed the effect of year, locations and infection pressure of pathogens. The tests revealed different reactions of the different varieties with respect to artificial inoculation. The experiments revealed different effects of the treatments. Whereas all varieties were more frequently diseased after inoculation with S. sclerotiorum, phoma inoculations displayed higher disease incidences only on cultivars Asgard and NK Morse but had no significant effect on cultivar Da Vinci.

109-114

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Interactions between winter oilseed rape canopy structure at flowering and Sclerotinia sclerotiorum epidemiology
Chloé Allart, Marine Gourrat, Odile Tauvel, Michael Geloen, Olivier Guerin and Xavier Pinochet

Abstract: Sclerotinia stem rot is one of the major diseases of winter oilseed rape. It is mainly controlled by fungicide application. Risk occurrence is estimated on petals, through the use of a petal kit. Nevertheless this epidemic potential is often limited by different environmental factors and plant infection capacities are strongly restricted. At the field level canopy structure can modulate conditions more or less able to favour the epidemic. We have looked for canopy structures able to modify disease impact. The initial hypothesis was that a closed canopy could favour the disease development by increasing local relative humidity and temperature. Field trials were carried out during two agronomic seasons with different genotypes and different plant densities. Infection potential, plant branching, petal fall kinetics on different parts of the canopy, wetness and temperature conditions inside the canopy and symptom occurrence was recorded. Results indicated (i) the plasticity of the plant and its ability to compensate at low plant densities, (ii) number of contaminated fallen stuck petals on leaves are not limiting for the epidemic, (iii) microclimatic differences inside and outside the canopy are not so important, (iv) disease incidence was higher for the lowest plant densities for the two locations where we got symptoms. This allows us to arrive at a new hypothesis that has not yet been tested.

117-125

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‘SYield’ – a risk alert system for Sclerotinia in oilseed rape
Jon West, Stuart Wili, Gail Canning, Steph Heard, Sophie Weiss, Patrick Jackman, Zac Coldrick, Andrew Mortimer, Guido Drago, Graham Johnson, Bruce Grieve, Keith Norman, Katherine Elsom, Katarzyna Kozan, Chris Easton, Gary Jobling, Ben Magri, Sarah Armstrong, Sarah Perfect, Derek Scuffell and Shradha Singh

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126

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Light leaf spot (Pyrenopeziza brassicae) – a resurgent problem in the UK
Neal Evans, Rishi R. Burlakoti, Peter Gladders, Faye Ritchie, Judith A. Turner, Coretta Klöppel and Bruce D. L. Fitt

Abstract: Since 2006, the incidence and severity of light leaf spot (Pyrenopeziza brassicae) in winter oilseed rape in the UK has increased so that the disease is now the main disease concern for growers with respect to yield loss. For example, in the springs of 2011, 2012 and 2013, > 70% of crops and > 30% of plants surveyed in England were affected by the disease. Crops have been severely affected in southern England as well as further north. It is thought that the increase in the prevalence of light leaf spot may be due to factors such as recent unusual weather conditions, a lack of resistance in currently grown varieties and poor disease control from poorly timed fungicide applications. Seasonal guidance for growers has been provided for more than 10 years by the on-line light leaf spot forecast but there is a need to refine predictions of epidemic onset in autumn to improve fungicide timing and overall disease management. National survey data highlight the need for new research to investigate the reason for this change in disease prevalence. This paper describes our current understanding of light leaf spot and work to be done in two new projects. One project aims to investigate pathogen development/epidemic onset in autumn and the role of subsequent components of the epidemic in epidemic progression. The other (PhD) project aims to investigate aspects of the light leaf spot pathogen populations with respect to improving varietal resistance.

129-133

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Molecular detection of pycnidiospores of Leptosphaeria maculans from tapes from spore sampler
Joanna Kaczmarek, Anna Stachowiak, Witold Irzykowski, Andrzej Brachaczek, Wojciech Langwinski, Adam Burzynski and Malgorzata Jedryczka

Abstract: Oilseed rape in Poland is exposed to two fungal pathogens, Leptosphaeria maculans and L. biglobosa, which cause stem canker of crucifers and are responsible for considerable yield loss. Considerable reduction of seed yield is attributed primarily to stem infection with L. maculans. The primary source of disease are airborne ascospores and secondary infection is caused by fungal pycnidiospores. Modern decision support systems that allow us to forecast the disease are based on the detection of ascospores using volumetric air samplers, but little is known about the detection limits of the secondary inoculum. Analysis of presence and concentration of airborne fungal spores may be performed either by means of conventional microscopy methods or PCR-based molecular techniques. This experiment was designed to optimise methods used for molecular detection of pycnidiospores of L. maculans from tapes obtained from spore samplers and processed in the same way as for the detection of primary inoculum. The sensitiveness of two methods was compared: traditional end-point PCR and Loop-mediated Isothermal Amplification of DNA (LAMP). The detection was done using pathogen DNA extracted from vaseline-coated Melinex tapes routinely used in 7-day volumetric spore samplers of the Hirst-type. The sensitiveness of the end-point PCR was 100 pycnidiospores and 50 spores using LAMP. Lower numbers of spores were also occasionally detected. The paper for the first time describes the use of the LAMP method for the detection of the secondary inoculum of L. maculans from tapes in volumetric spore samplers.

137-142

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Detection of Leptosphaeria maculans races on winter oilseed rape in different geographic regions of Germany and efficacy of monogenic resistance genes under varying temperatures
Mark Winter, Coretta Klöppel and Birger Koopmann

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143-144

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Evolution of Leptosphaeria maculans populations in a small area of the region Centre (France) following the introduction of oilseed rape hybrids carrying the Rlm7 specific resistance gene
Xavier Pinochet, Julien Carpezat, Sabrina Bichot, Gilles Sauzet and Martine Leflon

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145

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Verticillium longisporum: pathogen detection, diagnostics and cultivar resistance in U.K. oilseed rape (Brassica napus)
Thomas Wood, Sandra Chapman, David Lee and Jane Thomas

Abstract: Verticillium longisporum is an emerging pathogen of oilseed rape (Brassica napus) in the U.K. and both incidence/distribution of the disease appears to be increasing. The delay in the expression of symptoms in the host and the soil-borne nature of the pathogen hamper accurate detection and diagnosis. Chemical control strategies are currently ineffective and rotational management is the only option to minimise risk of disease. The identification of sources of genetic resistance is therefore a desirable strategy through which to reduce disease. In an effort to identify strategies to manage the risk posed by V. longisporum we generated a series of inoculated trials to screen a range of current U.K. varieties for resistance and used a CTAB/silicon dioxide pre-extraction, followed by conventional extraction to obtain DNA from a range of soil samples for subsequent analysis. Development of Loop Mediated Isothermal Amplification (LAMP) and qPCR based assays have enabled us to accurately detect and diagnose V. longisporum in a range of naturally and artificially infected soil samples. B. napus varieties varied for incidence of the disease and although complete resistance would appear to be absent in the varieties screened, a range of partial resistance was observed in specific cultivars. Detection assays currently provide semi-quantitative data for respective DNA concentrations and low (< 50 microsclerotia/50 g soil), moderate (< 100/50 g) and high (> 200/50 g soil) levels of infection can be detected. The identification for variation in resistance to V. longisporum amongst current varieties and the development of new diagnostic techniques will be utilised to investigate pathogen dynamics, yield loss and also to develop strategies to manage the risk posed to growers.

149-156

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Cross-resistance in winter oilseed rape (Brassica napus) against multiple vascular pathogens
Daniel Lopisso, Muhammad Farooq, Birger Koopmann and Andreas von Tiedemann

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157-158

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Studies of clubroot (Plasmodiophora brassicae) on oilseed rape in the Czech Republic
Veronika Řičařová, Khushwant Singh Sandhu, Jan Kazda, Miloslav Zouhar, Evženie Prokinová, Lenka Grimová and Pavel Ryšánek

Abstract: Clubroot caused by the pathogen Plasmodiophora brassicae (Wor.) has been spreading on winter oilseed rape in Czech Republic for the last three years. Research on P. brassicae in Czech Republic is therefore important for the adoption of management strategies against the disease under Czech environmental conditions. Pilot experiments with clubroot resistant cultivars of winter rape started in 2012. Experiments were made in greenhouse and field conditions. For greenhouse experiments, soil samples were collected from contaminated fields. Seeds of oilseed rape varieties declared by seed companies as resistant together with susceptible controls (variety Rohan and chinese cabbage variety Granaat) were sown both into soil samples and in the field that was severely and homogeneously contaminated by P. brassicae. Incidence and severity of symptoms on roots were evaluated after eight weeks. Presence of P. brassicae in roots was tested by PCR. Results obtained from both experiments were almost identical. Resistant cultivars Mendel, Mendelson, Alister and Andromeda showed no visible symptoms in any soil sample, although PCR confirmed pathogen presence in all cases. Similarly, the soil samples were also tested for the presence of P. brassicae using PCR. Furthermore, testing of soil samples at different dilutions by RealTime-PCR using TaqMan probes and SYBR green is in progress. The monitoring of clubroot P. brassicae pathotypes diversity in the Czech Republic is also planned and has already started.

161-168

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The importance of post harvest soil management in oilseed rape fields in reduction of clubroot severity
Nazanin Zamani-Noor

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169

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Infestation of Polish agricultural soils by Plasmodiophora brassicae on the Polish-Belarussian border in Podlasie province
Marek Korbas, Ewa Jajor, Joanna Kaczmarek, Agnieszka Perek and Malgorzata Jedryczka

Abstract: Extensive cultivation of oilseed rape worldwide, leads to tight rotations in regions suitable for the production of this cash crop. Growing of the same plant species on large areas and with only short breaks of crops having different requirements lead to accumulation of pests and diseases. In recent years in Poland a great increase of soil infestation by the soil-borne protist-like pathogen Plasmodiophora brassicae has been observed. This is why we have undertaken a methodical survey of agricultural soils in the whole country. In this paper we present the results of investigations done in 2012 and 2013 in Podlasie province (Podlaskie voivodeship) in counties located along the Polish-Belorussian border. The study was done in six counties, including one municipal county of Bialystok (1 sample) and five rural counties: Augustowski (7), Bialostocki (18), Hajnowski (8), Siemiatycki (9) and Sokolski (7). Apart from one sample from the field located in a municipal area, the samples were collected from 49 fields, 28 of which were located in typically rural communities and 21 originated from urban-rural communities. Sampling was done using a soil auger. Depending on field size, a sample was taken from 8 to 10 locations per field, 200 g of soil per location. In total ca. 1.6 to 2 kg of soil was collected per field. The detection of the presence of P. brassicae was done using a soil test performed in glasshouse conditions at 20 °C, using seedlings of two species of the genus Brassica, susceptible to P. brassicae. Eight weeks after sowing the plants were individually removed from the soil samples and were inspected for the presence on clubs on roots. The pathogen was found in 3 out of 50 fields monitored (6%), with one sample per Bialostocki, Hajnowski and Sokolski county. The pathogen was not found in samples from the field located in Bialystok municipal county. We conclude that the serious occurrence of P. brassicae is occasionally present in agricultural soils in Podlasie province in counties along the Polish-Belarussian border.

171-175

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Identification of the chromosome complement and genome recombination in interspecific hybrids and mutants within the genus Brassica, with known resistance to clubroot
Alicja Gronowska, Malgorzata Jedryczka, Janetta Niemann, Joanna Kaczmarek and Tomasz Książczyk

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176

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