Carrot fly (Psila rosae) control in Switzerland – current strategies and prospective developments*

Carrot fly (Psila rosae) control in Switzerland appears not to have been a major problem during the years 1985–2000. However, reports on crop losses due to increased damage, and yield lots not complying with raised quality standards, have become more frequent in recent years. Carrot fly control has clearly become more difficult because the fly’s population dynamics have changed (3 generations instead of 2) and due to changes in the cropping system. Furthermore, some insecticides with high efficacy, such as soil insecticides, are no longer available. Seed treatments with various insecticides were tested as potential alternatives to no longer approved soil insecticides, but these were not efficient enough when infestation pressure was high. Spraying, mainly with pyrethroids against the flies landing on carrot leaves, proved to be successful in some plots if the flight of adult flies was monitored with sticky traps and the timing of the insecticide treatments was adequate. However, in other cases treatment efficacy was low, presumably due to less precise timing of the applications. In conclusion, current experience on supervised chemical control indicates that strategies can be adapted, but Swiss agricultural research stations are not yet able to provide the growers with validated recommendations.     

The Identification and Exploitation of Resistance in Carrots and Wild Umbelliferae to the Carrot Fly, Psila rosae (F.)

Partial plant resistance to the carrot fly, Psila rosae, has been identified in several Nantes varieties of carrot, Daucus carota, which reduces larval damage to the roots and the number of pupae remaining in the soil after cropping by 50%. The resistance of the Nantes variety 'Sytan' was found to be consistent at 12 sites in 5 European countries over two seasons. The resistance has been shown to be based on antibiosis and correlated with concentrations of chlorogenic acid in the roots. The resistance complements cultural and chemical methods for controlling P. rosae. Thus, in field experiments over two seasons it was shown that carrots could be left in the ground for a longer period providing a greater sowing/harvesting interval with a resistant variety than a susceptible one because of the reduction in damage and the delayed development of insects on the resistant variety. In two seasons at two sites a partially-resistant variety required only one-third of the dose of insecticide to provide a marketable crop compared with a susceptible carrot variety. In a breeding programme involving the variety 'Sytan', male sterile lines, inbreds and selections with improved levels of resistance were developed. Much higher levels of resistance were identified in certain wild Daucus species and 15 years of crossing and selection produced lines with significantly higher levels of resistance than exists in the variety 'Sytan'. A range of resistant carrot material bred at Horticulture Research International has been released to seed companies for use in the production of improved carrot varieties. The partially-resistant variety 'Flyaway' was made available to amateur gardeners in 1993 and to commercial growers in 1995 as a result of this research.     

Supervised control of the carrot fly in the Netherlands; insights from a dirty dataset1

‘De Groene Vlieg’ (the Green Fly) is an independent company offering various services concerning integrated pest management in open field agriculture in the Netherlands. One such service is the supervised control of carrot fly (Psila rosae). From 1993 to 2008 the company has monitored the carrot fly population on a total of nearly 65 000 hectares resulting in an extensive dataset. The data was not collected according to proper experimental methods, hence it is titled dirty, but the size of the dataset does allow valuable insights to be gained. De Groene Vlieg monitors the carrot fly population on each field separately. Sticky traps are collected weekly and flies are counted in the laboratory. Growers receive messages containing advice regarding when to apply insecticides and they are responsible for doing so. Overall, over a third of the fields require no spraying at all and for 75% of the fields growers are advised to spray three times or less. One insight from the dataset is that small carrots require more insecticide treatments than large carrots (‘winter carrots’). Reasons for this difference are probably both regional and cultural. Additionally, focusing on a small and uniform area reveals that carrot fly population dynamics are highly variable between years. Another insight is that sowing date has a large effect on the number of insecticide sprayings that are required. Fields sown before the first flight have more flies in the second flight than fields sown later. Comparison of biological and conventional carrot fields shows that carrot fly populations are similar for the first flight. However, during the second flight the number of flies is much higher on organic fields than on conventional ones. Finally, insecticide seed treatment with chlorfenvinphos to control the reproduction of the first flight appears slightly more efficient than supervised control. However, supervised control seems as efficient as seed treatment with clothianidin and beta cyfluthrin.     

Review of carrot fly control in Northern Europe – 20091

In February 2009, the European and Mediterranean Plant Protection Organization (EPPO) held a workshop to discuss the management of carrot fly (Psila rosae) within Europe. Prior to the workshop, participants completed a questionnaire about carrot fly and current control methods and some of the information is summarised in this paper. In general, this pest is controlled adequately at present, but there is a heavy reliance on insecticides. The responses to the questionnaire highlighted a number of issues, in particular: the limited range and efficacy of the insecticides available at present, concerns about the availability of effective control measures in the future and a need for improvements in the targeting of treatments through forecasting and monitoring and the use of treatment thresholds.     

State of the art regarding carrot fly control in practice and possibilities in the future for Western and Northern Europe1

The carrot fly (Psila rosae) is a major pest of umbelliferous crops, particularly in carrot production. This pest is present in temperate regions of Northern and Western Europe and also in the warm and dry climate of Central and Southern Europe. Currently, control strategies are limited and there may be a bottleneck of pest control solutions in the future. In practice, growers in the Netherlands mainly rely on a commercial, supervised control system which monitors the carrot fly population pressure. Possibilities to control the carrot fly after exceeding an economical threshold are reduced due to a lack of efficient chemical insecticides. Another option is the use of seed treatment to protect the carrots against the larvae developed from the first flight of the carrot flies for 12–14 weeks after sowing. The state of the art of the carrot fly pest and control possibilities are hereby discussed. Bottlenecks in control of carrot flies are highlighted and described.     

A brief review of the status of fireblight in UK1

Fireblight (due to Erwinia amylovora) has continued to spread northwards and westwards in UK. In SW England, the disease has been particularly severe in perry pear orchards, causing the loss of many thousands of mature trees, and in cider apple orchards. Cider apple trees are not rapidly killed but crop losses have been severe in some years. The disease has become established in the NW midland counties of England and also in Wales. Outbreaks have occurred as far north as Lancashire just above the administrative line which separates the affected area from the disease-free (clear) area. Spread has occurred through infections in Crataegus hedges, especially along motorways, and also through movement of infected ornamental species. New legislation is envisaged which will redefine the clear area and increase the protection given.     

Effects of phorate placement on carrot fly control,seedling density and terminal residues in the crop

The application of granules containing 10 % phorate at 1.12,2.24 or 4.48 kg a.i./ha in a narrow slit together with carrot seed significantly reduced seedling emergence in both a mineral and peat soil. When the granules were applied at 2.24 or 4.48 kg a.i./ha in a narrow slit 2.5 cm below the seed, seedling emergence was adversely affected only at the higher rate in the mineral soil. Phorate granules applied with the seed in the peat soil gave a significantly lower plant density than when applied below the seed, but subsequent carrot yields were unaffected because much larger roots were produced. All phorate treatments gave effective reduction of carrot fly larval damage to the roots. On the peat soil, there were significant increases in total phorate residues present in mature carrots with increasing rate of phorate granules placed with the seed. Placement of the granules 2.5 cm below the seed resulted in a 50% reduction in total residues of phorate in whole carrots compared with placing the granules with the seed. Residues resulting from 1.12 kg a.i./ha with the seed or 2.24 kg a.i./ha 2.5 cm below the seed were not significantly greater than residues in untreated carrots.     

Evaluation of different types of compost tea to control rose powdery mildew (Sphaerotheca pannosa var. rosae)

Powdery mildew (Sphaerotheca pannosa var. rosae) is an important foliar disease which is found in all rose-producing greenhouses. An experiment was carried out in a commercial greenhouse in Hashtgerd, Iran, in 2014 to investigate whether compost teas can be used to control this disease. Taguchi's design of experiment (Taguchi's DOE) method was used to plan a minimum number of experiments and optimization to control rose powdery mildew. The test included three factors, namely the different types of compost tea (aerated and non-aerated compost tea, aerated and non-aerated vermicompost tea), the dosage (1:8 and 1:16, compost:water), and the number of spray applications (once and twice per week). The experiment was set up as an orthogonal array L₈ with three replicates. Based on the experimental results, the optimum treatment combination for controlling rose powdery mildew was found to be aerated compost tea with 1:8 dilution with an application of twice per week.     

Effects of placement and distribution on the performance of granular formulations of insecticides for carrot fly control

Effects of granule distribution relative to carrot rows are discussed and further results described. Placing insecticides 5 to 10 cm deep 7.5 cm away from the centre line of the carrot row usually, but not always, improved their performance compared with bow-wave applications. Both sides of the row need to be protected. The efficiency of chlorfenvinphos in a sandy loam, and phorate in a peaty-loam, decreased with increasing distance from the row but they were slightly effective even 19 cm away. The optimum depth for side-placing granules at sowing time varied from 5 to 10 cm, and combining side-placement with a bow-wave application did not greatly enhance efficiency. The most effective combination on a peaty-loam was a bow-wave application of 3 kg phorate/ha at sowing time followed 6 to 9 weeks later by a similar amount side-placed 7.5 cm deep 7.5 cm from the row centre. Comparison of the performance of phorate broadcast, applied by the bow-wave method or deep side-placed indicated that efficiency was improved by restricting the granule distribution but that higher concentrations of granules were then needed in the treated zones to be equitoxic with more uniformly broadcast granules. Uptake by the carrot root system is an important factor in the action of insecticides against carrot fly larvae.     

Biological control and plant health in the UK1

The protected crop environment has long been recognized as offering particularly good opportunities for the application of biological control and this is reflected in the predominance of integrated pest management programmes and the wide range of biological control agents available. The introduction of new pest species of quarantine concern can often occur in glasshouse crops, as a result of international trade in plant material, and can have a highly disruptive impact upon well established, integrated pest management programmes. The use of biological control agents against quarantine pests is discussed, including both the use of exotic species and those established in the UK. The relevant legislation in the UK is outlined in relation to the introduction of non-native species, including both plant protection and conservation interests. Environmental safety aspects such as the impact of such introductions on non-target species and issues of quality control to prevent the introduction of contaminants are noted as of particular plant health interest.     

杨梅果蝇综合防治技术研究

从农业、物理、生物防治的角度出发,对昆明地区为害杨梅的果蝇进行综合防治技术研究,结果表明,果蝇对颜色无明显趋性,对气味较敏感,对水、糖、醋、酒比例为10∶6∶3∶1的糖醋液趋性最强;生物源杀虫剂0.3%印楝素乳油300倍液、600倍液,2.5%多杀菌素悬浮剂600倍液对为害杨梅的果蝇均具有较好防效,且对果品安全;及时清除地上落果并运出果园集中处理,也是较好的农业防治措施。     

桔小实蝇生物防治研究进展

本文综述了国内外桔小实蝇的生物防治研究进展,概括了国内外对桔小实蝇起主要控制作用的主要天敌种类,论述了桔小实蝇寄生性天敌、捕食性天敌的利用;病原微生物中真菌、线虫、共生菌等的利用;对桔小实蝇具有引诱作用的水解蛋白、化学物质和植物次生物利用;桔小实蝇不育技术的应用等方面,并讨论了今后持续控制桔小实蝇中生物防治方面的发展趋势,以期为今后桔小实蝇持续控制提供生物防治方面的参考。     

The influence of anticoagulant resistance on effective rodent control in the UK1

Widespread use of warfarin, and other multiple-dose anticoagulants, selected populations of warfarin-resistant rodents in the UK and in other countries. The effectiveness of rodent control was dramatically reduced when the resistant animals formed a large proportion of a population. The second-generation anticoagulants were developed to overcome these practical control problems with warfarin and were considered to be effective rodenticides against warfarin-resistant populations. In the UK, however, difenacoum showed reduced efficacy for controlling an established warfarin-resistant Rattus norvegicus population covering a substantial area of farmland in southern England. Continued use of difenacoum selected for difenacoum-resistant animals, so that the rodenticide is now ineffective for controlling rats in three counties. Brodifacoum was subsequently used to control some infestations and there is evidence that these treatments selected for animals with an increased level of resistance to brodifacoum. Anticoagulant resistance in Mus domesticus is less of a practical problem because of the availability of non-anticoagulant rodenticides for the control of this species. There is evidence, however, of bromadiolone resistance in M. domesticus trapped on farms in the UK. Recent investigations of the mechanism of anticoagulant resistance in R. norvegicus have indicated that vitamin K3 (menadione) is an antidote to anticoagulants in resistant animals. This form of the vitamin is included as a dietary supplement in poultry and pig food and would aid the survival, and therefore increase the selection, of resistant animals when anticoagulants are used exclusively.     

Susceptibility of wild carrot (Daucus carota ssp. carota) to Sclerotinia sclerotiorum

Sclerotinia soft rot, caused by Sclerotinia sclerotiorum, is a severe disease of cultivated carrots (Daucus carota ssp. sativus) in storage. It is not known whether Sclerotinia soft rot also affects wild carrots (D. carota ssp. carota), which hybridise and exchange genes, among them resistance genes, with the cultivated carrot. We investigated the susceptibility of wild carrots to S. sclerotiorum isolates from cultivated carrot under controlled and outdoor conditions. Inoculated roots from both wild and cultivated plants produced sclerotia and soft rot in a growth chamber test. Two isolates differed significantly in the ability to produce lesions and sclerotia on roots of both wild carrots and cv. Bolero. Flowering stems of wild carrots produced dry, pale lesions after inoculation with the pathogen, and above-ground plant weight was significantly reduced 4 weeks after inoculation in a greenhouse test. Wild and cultivar rosette plants died earlier and fewer plants survived when inoculated with the pathogen under outdoor test conditions. Cultivar plants died earlier than wild plants, but survived as frequently. Plants inoculated in the crown died earlier and at a lower frequency than plants inoculated on leaves. Wild carrots may thus serve as a host of S. sclerotiorum and thus eventually benefit from any uptake of resistance genes, among them transgenes, via introgression from cultivated carrots.     

First report of cyromazine resistance in a population of UK house fly (Musca domestica) associated with intensive livestock production

BACKGROUND: House fly control in livestock‐rearing facilities is heavily reliant on the use of the larvicide cyromazine. While extensive use of this compound has led to the development of resistance in several countries, no elevated tolerance has so far been reported from the United Kingdom. RESULTS: Tolerance to cyromazine in larvae derived from a field strain collected at an intensive pig unit was significantly elevated over that of insects taken from a susceptible laboratory strain. Resistance factors (RFs) of 2.9 and 2.4 were returned for assays initiated with eggs and neonate larvae respectively. The RF for field strain larvae exposed from neonate increased significantly to 3.9 and 5.6 following rounds of selection at 1.0 and then 1.5 mg kg^?1 cyromazine. CONCLUSION: Low‐level resistance to cyromazine in UK house flies is reported here for the first time. The geographic extent of this resistance is unknown but, if widespread, may lead to control failures in the future, and indicates that careful stewardship of this compound in the United Kingdom is now required. © Crown copyright 2010. Reproduced with permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.     

Computer aids to integrated control in peach orchards in Emilia-Romagna (Italy)1

An Integrated Pest Management (IPM) programme on vineyards and orchards has been applied since 1974 in Emilia-Romagna (northern Italy). The Entomology Institute of Piacenza has the scientific responsibility for peach, plum and apricot orchards. Data is collected in the field by a team of technicians with province-level co-ordination. Directions for control are given directly to farmers or through answering machines, Videotel or weekly bulletins. Data from orchards, concerning the pest and disease situaton, are processed by two Hewlett Packard 9000 computers: an HP 9845B and an HP Vectra RS/20. With the latter, data exchange is possible with MS DOS operating systems, allowing data input from a regional computer network now at the development stage.