Crop Module: Celeriac - Red Tractor Assurance
Contents
1. handling is important and there should be adequate provision made for the removal of any free soil Storage temperature Temperatures should be reduced as quickly as possible in refrigerated stores therefore adequate refrigeration capacity is needed Ambient temperature stores need to be blown for two days after loading to lower the initial respiration rate of the crop In both types of store ambient air should be used initially to dry and cool the crop Celeriac will keep well into the New Year in an insulated store using ambient air conditioning Such stores can be automated using a differential thermostat for efficient use of ambient air temperatures Refrigeration is essential for longer term storage with temperatures between 0 1 C a See e S Te SE RESIDUES AND CONTAMINANTS Red Tractor Farm Assurance Fresh Produce is aware that a key area in the production of fresh produce which requires continued attention by growers and their advisers is that of keeping pesticide residues to a minimum The issue is not just one of meeting the MRL trading standard but ensuring that any individual or multi residues are kept as low as possible below this level The key targets are Minimising late application of fungicides and insecticides to the edible part of the crop m Ensuring minimum harvest intervals are followed m Ensuring that application equipment is applying products correctly APPENDIX 1 TYPICAL APPLICATION RAT2. to grow evenly Corrective action a First establish the nature of any problem by receiving regular updates on monitoring and forecast services such as the HDC Pest Bulletin hosted by Syngenta and available through the HDC website These will provide information on any general prevailing threat b Monitor crops at regular intervals to detect the early presence of any pests or diseases Care needs to be taken to correctly identify any potential pest or disease so that any corrective action is appropriate c Consider any prevailing factors which may mean the pest or disease becomes less significant e g dry weather slows disease progress but wet weather may reduce the threat from cutworm damage d The timing of an agrochemical input can seriously affect its efficacy As a general rule applications early after infection or infestation are more effective than late applications therefore regular crop monitoring to detect early problems is essential e If chemical control is needed the following points should be considered m use the least toxic and persistent product m use the most selective product to reduce the impact on naturally occurring beneficial organisms m use the minimum effective dose rate m use appropriate application methods with properly maintained equipment exceeding the dose is illegal under COPR PEST DISEASE AND WEED CONTROL PEST CONTROL Carrot fly Carrot fly Psila rosae is widespre
3. which have been found to be both workable by the grower and beneficial to the environment The aim is to transfer such information and technologies to growers Acknowledgements Red Tractor Farm Assurance Fresh Produce gratefully acknowledges the contribution of all consultees in the preparation of this protocol particularly Robin Buck and Julian Perowne of Jack Buck Farms Ltd Front cover image credit Jack Buck Farms ADDITIONAL REQUIREMENTS AGAINST CURRENT STANDARDS CROP SPECIFIC STANDARDS CHOICE OF VARIETY OR ROOTSTOCK AND PLANT HEALTH CERTIFICATION 03 SITE AND SOIL MANAGEMENT ENVIRONMENTAL PROTECTION AND CONTAMINATION CONTROL PEST DISEASE AND WEED CONTROL NUTRITION HARVEST AND STORAGE RESIDUES AND CONTAMINANTS APPENDIX 1 TYPICAL APPLICATION RATES FOR NUTRIENTS ADDITIONAL REQUIREMENTS AGAINST CURRENT STANDARDS 02 02 03 04 05 09 10 10 11 None for this crop module CROP SPECIFIC STANDARDS STANDARDS CQ 54 a Macro and micronutrient must be tested by assessing samples of soil or leaf tissue CQ 54 b Soil nitrates must be monitored in the growing season HOW YOU WILL BE MEASURED Table in the celeriac protocol text provides further information 8 Red Tractor Assurance for Farms Crop specific Module Celeriac RECORDS to be kept for 2 years m Soil leaf tissue testing results m Soil nitrate monitoring records Assured Food Standards 2015 2 GUIDANCE CHOIC
4. E OF VARIETY OR ROOTSTOCK AND PLANT HEALTH CERTIFICATION DEFINITIONS Celeriac Apium graveolens var rapaceum belongs to the umbelliferae plant family which also includes carrots parsnips and celery Umbelliferous herbs and spices include parsley fennel dill chervil lovage angelica caraway aniseed and cumin Important umbelliferous weeds prevalent in the UK include cow parsley fools parsley and hemlock Celeriac is a biennial growing vegetatively from seed in the first year into a swollen stem storage organ following leaf senescence in the autumn Re growth in the following spring produces a flowering stalk and following fertilisation seeds are produced in the late spring early summer Celeriac is similar to celery exhibiting similar shaped leaf petioles and leaflets The leaf bases are attached to the stem As swelling of the stem occurs rapidly in the autumn harvesting is generally left until late October and into November to maximise yield SITE AND SOIL MANAGEMENT SITE SITUATION Celeriac originates in the Mediterranean basin and has warm temperate growth requirements Optimal temperatures for growth lie between 15 C and 18 C growth ceases at below 7 C and above 24 C For this reason it is important that cold sites e g shaded by woods north facing etc are avoided South facing fields offer the best thermal advantage As celeriac can suffer frost damage at temperatures lower than 1 C so harvesting need
5. ES FOR NUTRIENTS Major nutrient requirements kg ha The following P K and Mg table is based on assessment of soil samples and originates Fertiliser Recommendations RB209 2010 8 Edition Celeriac N P K or Mg Index 2 Nitrogen N Phosphate P O Potassium K O Nitrogen applications can be split 2 3 base then 1 3 top dressing in July August The following table shows the ADAS classification of soil analysis results into Index values Nutrient Need Index Phosphate mg l Potassium mg l Magnesium mg l Be o e O vw y e High response 10 15 61 120 26 50 Responsive 16 25 121 240 51 100 Little response m ee 46 70 401 600 176 250 No response 71 100 601 900 251 350 Nitrogen fertiliser adjustment Some response 26 45 241 400 101 175 Fertiliser experiments in a range of vegetable crops in Holland have determined the total amounts of nitrogen from available from the soil and applied fertiliser above which crops do not respond If soil available nitrogen is known then fertiliser applications can be adjusted so that the total nitrogen lies at maximum crop response The N min method attempts to indicate the nitrogen that has mineralised from organic matter and is available for crop uptake as nitrate or ammonium ions in the soil water Soil samples O to 30 and 30 to 60cm depths are needed If 25 subsamples from each soil horizon are taken from a maximum area of 4 ha there should then be one bulked sample of 1
6. N ha deduct the N min value from the desired level A further mineral N sample should be taken prior to top dressing Excess Nitrogen applications can lead to impaired storage An Approach to Target Values published in Enveg News June 2000 for mineral N comes from German trials The target value is made up from 1 expected N uptake of the crop 2 necessary N min residue in the soil at harvest time 3 expected net N Min mineralisation Thus N Min target value at planting for a 20ton ha celeriac crop 0 60cm soil depth is 180kg ha Note this was under German growing conditions NOTES Red Tractor Assurance for Farms Crop specific Module Celeriac Assured Food Standards 2015 Certification Body Beef and Lamb Certification NSF Certification Hanborough Business Park Long Hanborough Oxford 0X29 8SJ Tel 01993 885739 Email agriculturefansf org Web www nsf foodeurope com SFQC SFQC Ltd Royal Highland Centre 10th Avenue Ingliston Edinburgh EH28 8NF Tel 0131 335 6605 Email redtractorfdsfgc co uk Web www sfqc co uk e kiwa Partner for progress Kiwa PAI The Inspire Hornbeam Square West Harrogate North Yorkshire HG2 8PA Tel 01423 878878 Email paienquiriesfakiwa co uk Web www kiwa co uk pai Fa NIFCC Northern Ireland Lissue House 31 Ballinderry Rd Lisburn Northern Irel
7. Red Tractor Assurance Fresh Produce Scheme Crop Module Celeriac Effective 1 September 2015 Red Tractor g Assurance for Farms Q Fresh Produce Scheme Welcome written to complement and avoid duplicating the generic principles of the Red Tractor Farm Assurance Fresh Produce Scheme standards It is advisable to read the Red Tractor Farm Assurance Fresh Produce standards before reading this crop specific module This module is designed to stimulate thought in the mind of the reader It contains crop specific guidance and standards where applicable in addition to the requirements stated in the generic Fresh Produce standards Te crop specific module for celeriac has been Within this module the important requirements outlined in the crop specific standards section will be verified during the Red Tractor Farm Assurance assessment and compliance will form a part of the certification approval decision Disclaimer and trade mark acknowledgement Although every effort has been made to ensure accuracy Assured Food Standards does not accept any responsibility for errors and omissions Trade names are only used in this module where use of that specific product is essential All such products are annotated and all trademark rights are hereby acknowledged Notes Pesticide Information The Red Tractor Fresh Produce team has been working with Fera to provide tailored access to the LIAISON database for all Red Tractor F
8. abel instructions allow such mixing for operator safety reasons Pirimicarb has both contact and vapour phase action working best between 15 25 C under still conditions effectiveness is largely lost when windy If peach potato aphids are present the following table provides a guide for effective product types S R1 R2 R3 emee foree we EE IE Note As resistance increases from S to R3 aphid colour changes from lime green to rosy pink b Modified acetylcholinesterase i e MACE resistance MACE resistant peach potato aphids only show resistance to pirimicarb other aphicides are effective However in 1996 when MACE resistance was discovered it was only found in association with Esterase resistance this then gives the following table of effective products MACE MACE MACE MACE R1 R2 R3 Pyrethroid Pymetrozine Pymetrozine CUTWORM Cutworm is a general term given to the caterpillar larvae of the turnip moth However in some years the heart and dart moth large yellow underwing moth and garden dart moth larvae may also cause cutworm iype problems Particular risk of attack occurs under dry weather conditions on a range of broad leaved crops including celeriac grown on light soils Adult moths emerge from May or early June until the end of July Eggs are laid on the leaves of host plants young caterpillars hatch 10 to 14 days later and begin feeding on the leaves After three instars the growing cater
9. ad in the UK as a wide range of cultivated umbelliferous crops carrots parsnips etc and weeds e g cow parsley and wild parsley act as suitable hosts Using land virgin to umbelliferous crops unfortunately does not eliminate the risk of carrot fly attack First generation adult flies emerge from pupae in May and follow the scent from umbelliferous plants or crops by flying upwind towards the new host Adult carrot flies prefer to live in shelterbelts adjacent to umbelliferous crops where they feed and mate Eggs are laid in the crop in soil cracks near the host plant Approximately 7 days later a colourless 1 stage larva hatches out and burrows into the soil to begin grazing externally on the roots This may lead to young plants dying and plant stands becoming gappy Later 29 and 3 stage larvae burrow into the root to form mines The older 3 stage larvae are creamy white and 8 10mm long after which they pupate in the soil close to the taproot After further development a second generation adult carrot fly emerges Second generation carrot flies are usually first detected in late July or early August depending on the season If is the second generation that is considered to be the most serious as the mining of the roots spoils their appearance and reduces the crop value Carrots and parsnips are often stored over winter in the ground which means they may be a source of first generation carrot fly the following spring i
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11. d crops harvested before the end of September rarely need control Carrot Fly do not travel great distances so treatments should be concentrated on the outsides of fields and headlands should be harvested and marketed first However the second generation lasting from late July to the middle of September can be damaging Control measures should be taken 10 days before the predicted egg laying Whilst fleece or crop mesh can be useful for small areas chemical measures using Lambda Cyhalothrin have been very successful The insecticide should be applied in warm evening temperatures every 12 14 days whilst egg laying continues to be forecast with a maximum of 400ml product ha of crop c The use of the pest forecast can and should be supplemented by the use of sticky insect traps Yellow sticky traps should be placed just above the crop at 45 degrees with the top edge towards the field margin The height will need adjusting as the crop grows The traps should be inspected and changed weekly and can be sent for identification confirmation to specialist service providers It is important to note however that the risk of Carrot Fly attack may vary widely from field to field thus a general forecast will not be sufficiently meaningful to cope with particular hot spot fields Sticky traps are essential in hot spot areas Aphids Several aphid species attack celeriac but only one the peach potato aphid Myzus persicae has shown resi
12. f compaction is found these layers should be removed by deep cultivations and or subsoiling Pans are best broken whilst the soil is dry as subsoiling implements then produce a good shattering effect Wheelings in subsequent cultivations etc should be limited to avoid any further compaction The use of ploughs power harrows bed formers destoners declodders etc will depend on the soil type with the aim of minimising the number of operations and passes to produce a bed with a fine tilth on top and good structure below A stone and clod free bed is ideal with a fine tilth extending 10cm deep If beds are drawn up well before drilling removing weeds with a non selective herbicide can produce a stale seed bed Early bed forming under cool spring conditions also conserves moisture by limiting evaporative losses from cultivations The most suitable soil type for celeriac has been found to be sandy loams sandy clay loams and silts although other soil types can produce acceptable crops Care needs to be taken if heavier soils are selected as wet conditions in the autumn may make harvesting difficult Celeriac does tolerate acid soils but yields of celeriac may decline unacceptably if the soil pH is below 6 3 The optimum pH lies between 6 5 and 7 0 More alkaline soils should be avoided as celeriac is prone to boron deficiency The availability of boron is greatest in neutral soils and much less in alkaline pH soils It shou
13. f poor control was achieved Carrot fly control is best achieved by integrating several cultural measures The following points are helpful a Site risk assessment Some sites are inherently at more risk of carrot fly pest attack than others therefore select low risk fields Factors that increase probability of attack are m Close vicinity to previous umbelliferous crops Carrot flies can travel some 1 5 kilometres from one crop to another but damage will reduce very significantly over 1 kilometre m Over wintered Carrot and Parsnip crops pose particular risk to crops planted in the following spring m Proximity of ditches hedges etc which allow broad leafed weed plants to provide shelter along field edges fields which are long and thin with suitable shelter along a long edge present particularly high risk m Close umbelliferous crop rotations this generally means umbelliferous crops in close vicinity to each other in and between years m Poor disposal of heavily infested crop material a cull pile may translate into a carrot fly insectory if not properly destroyed b HDC Syngenta Pest Bulletin This day degree based forecast has developed into a reliable tool for predicting and controlling Carrot Fly The pest bulletin is available to all HDC levy payers and gives advice regionally on predicted egg laying activity It can be found on the field vegetable section of the Syngenta website The first and third generations an
14. he preceding season and so it is advisable that growers are aware of these crops and plan to be 1 kilometre away if possible Note When sending soil samples for assessment careful handling is needed as any shock e g dropping may rupture the nematodes and reduce the result SOIL MANAGEMENT Soil structure cultivations type amp pH Celeriac will not tolerate poorly drained soils so a good soil structure which allows excess water to drain is essential to satisfactory crop performance Stems are prone to mechanical damage when harvested from the soil that may lead to unsightly brown discoloration of the flesh Similar constraints apply to other root crops so the preferred soils are those which can be managed freely and do not contain excessive stones or clods Celeriac can suffer slow growth from soil compaction It is therefore important that soils are free of pans or compacted layers that will ensure the roots are unimpeded This is particularly important if irrigation is not available Cracks on the surface of the celeriac can occur if the growth is uneven possibly due to wet dry conditions The correct cultivation sequence can only be determined after first examining the soil structure Examinations are best made using a soil pit as this readily shows to what extent and to at what depth any compacted layers exist Soil augers spade or hand fork can be used to determine soil structure to depth at points across a field I
15. kg ready to be sent for soil N min assessment It is important bulked samples are frozen if they are not immediately sent for analysis as increased temperatures and thereby increased soil bacterial activity might otherwise lead to a false reading Sampling needs to occur close to planting 2 to 3 weeks but before soil cultivations If animal manures are to be applied a period of 6 weeks should lapse between manure application and N min sampling Top dressing manures onto a growing crop is not recommended The laboratory assessment should provide a report sheet indicating the nitrogen available as nitrate and as ammonium in ppm Most report sheets also provide a conversion of ppm into a value of available nitrogen as kg N ha In case no such conversion is provided the following guide may be used For the sampled soil horizon i e O to 60cm add together the nitrate and ammonium ppm values to give the total available nitrogen in ppm for that horizon Multiply the total available nitrogen ppm value by one of the following factors to result in kg available nitrogen ha Dry sand Moist sand Dry clay Dry silt Moist clay Dry peat Dry loam Moist loam Moist peat Moist silt Note This table assumes a soil bulk density of 1 4 if the actual soil bulk density is markedly different from this multiply the total available nitrogen ppm value by the known bulk density then divide by 1 4 To calculate the nitrogen fertiliser requirement in kg
16. ld be noted sandy soils tend to be particularly prone to boron deficiency ENVIRONMENTAL PROTECTION amp CONTAMINATION CONTROL THE BASIC APPROACH TO CROP PROTECTION Celeriac is susceptible to a number of pests and diseases but as a guiding principle pesticide inputs should be minimised through prevention rather than cure An integrated approach should be adopted to achieve this by involving the following management steps a Itisa useful principle to attempt to grow celeriac crops in isolation then if pest and disease infestations occur they are late and less prolific b Sensible crop rotation avoids the build up of soil borne problems or disease carry over from one crop to the next Cultural preventative techniques a Any crop waste left in the field should be ploughed in immediately after harvest to promote rapid breakdown by soil microbes This prevents the debris acting as a source of inoculum to remaining unharvested crop b Any crop waste from crop stores needs to be collected together before being taken to a designated dumping zone where it is preferably buried Returning stored waste to the source field is likely to result in the establishment of soil borne diseases and should be avoided c Crops enjoying good plant health through nutrient supply are more tolerant to pest and disease attack d General plant health may also be assisted by reducing stresses e g the judicious use of irrigation allows plants
17. mily onions garlic chives and shallots As sclerotia last for considerable periods of time in the soil the key to long term cropping is to prevent this disease establishing to begin with Sclerotinia free land may be sustainably cropped with vegetables so long as break crops are used in the rotation This has the effect of maintaining inoculum at low levels or to decline in the absence of suitable host crops Sclerotinia may be particularly aggressive on celeriac in store where the high humidities and wet surfaces allows the pathogen to develop freely Managing the storage conditions may help to limit disease expression but it is most useful if inoculum from the field is minimal at harvest The use of Sclerotina free land for celeriac cropping is helpful It is advisable that crops for long storage are carefully rogued before harvest Infected plants should be placed in plastic bags and removed from the field Azoxystrobin or Fludioxinil amp Cyprodinil will have some impact on early Sclerotinia field infection Septoria Septoria is potentially a serious foliar disease that arises from infected seed Under wet warm conditions foliar symptoms spread rapidly The use of thiram soaked seed limits disease expression to very low levels early in the season Available fungicides may be used but as they are only protectants the environmental loading needs to be considered because once disease has been detected in the crop treatme
18. niques For crops planted in May a stale seedbed technique will enable useful control of emerging annual weeds and allow some control of volunteers Very low well timed doses of linuron at weed cotyledon stage can give satisfactory results APPROVED USES NOT INCLUDED ON THE PRODUCT LABEL In many circumstances particularly for minor crops product labels do not include all of the approved uses and growers wishing to check the approval notice of a particular product should note that this information is available using the LIAISON search accessible via their Red Tractor Farm Assurance home page after logging in Asearch on the Extension of Authorisation for Minor Use page of LIAISON by crop or product name should yield a results page A click on the product name should link to a summary of the approval information Near the bottom of the summary is the specific off label number e g 0246 09 and this link will open up a pdf of the current EAMU document giving details of the extension of use Nutrition An inadeguate nutrient supply results in indifferent yields As almost all plant nutrients are taken up as ions supplied from soil reserves in the soil water managing soil nutrition reguires careful attention to establish the correct soil nutrient conditions before planting Monitoring crops during growth is helpful to enable remedial treatments by foliar feeds or top dressings but the yield penalties incurred by early n
19. nt is unlikely to give good control It is desirable to use seed guaranteed to be free from infection by the seed supplier Phoma Generally Phoma is more problematic in store rather than in the field The fungus survives in crop debris between susceptible host crops thus limiting soil inoculum build up by ensuring good rotational intervals between celeriac crops is essential The expression of disease in store partly depends on the level of wounding at harvest so gentle handling helps reduce disease levels BACTERIAL DISEASE A range of bacteria mainly Erwinia and Pseudomonas species may attack celeriac in store Wounding at harvest and poor storage conditions warm wet surfaces on the swollen stems in particular make disease expression worse Licorice rot This soil borne disease tends to be seen in stored crop As there is no effective chemical control available crop rotation with wide intervals is essential to prevent inoculum building up in the soil Grey mould rot This disease tends to show in store but may be seen in the field under particularly prolonged wet conditions The fungus may reside in the soil surviving as spores between host crops Good crop rotation intervals are the main means to limit soil inoculum build up WEED CONTROL There are few herbicides approved for use in celeriac and the list is likely to diminish rather than increase The maximum use should be made of good site selection and cultural tech
20. or many crops toxicity occurs when soil boron exceeds 4 0mg l Where treatment to soil is required boron can be applied either as Borax at 22kg ha as granule usually blended in with other fertilisers to achieve the necessary bulk to apply evenly or alternatively as a liquid as Solubor applied at 11kg ha in 200 to 500 litres water ha If foliar treatment is required e g where unsuitable soil pH reduces boron availability Solubor maybe applied at 5 5kg ha in 200 to 500 litres water ha higher water rates are needed on tender or young plants HARVEST AND STORAGE HARVEST Time of harvest Harvest timing will depend on the market specification of the final root size Celeriac crops can bulk up quickly in October so careful and regular monitoring is necessary Early crops grown with crop covers can be ready in early August especially if irrigated Harvesting Accurate topping is important as any overtopped roots are effectively valueless Accurate topping also minimises the amount of foliage in store Mechanical handling can damage the root and as many of the storage diseases require wounds to enter into the swollen stem care is needed in all harvesting and handling operations STORAGE Loading stores Storage can be either in bulk or in boxes There is rarely a problem of compression damage in bulk stores as celeriac can be loaded up to at least 4 metres in height Cooling and drying should be the first priority Careful
21. pillars drop to the soil surface and burrow into the soil to begin feeding on roots and tap storage roots Root feeding over July and August may cause serious damage to crops Over winter the caterpillars remain underground become fully fed and eventually pupate between February and May after which development towards adult form progresses Control of cutworms depends on killing the leaf feeding caterpillar stages Control measures are ineffective once burrowing into the soil has occurred Two main options for control are water droplets i e rain irrigation or insecticide application Water particularly as heavy droplets striking crop leaves knocks young caterpillars to the soil surface where they are unable to find leaves again and eventually die A minimum of 12mm of heavy rain or 25mm of irrigation is effective at controlling cutworm larvae Note If irrigation is to be relied upon even applications are required as no control will be exerted in the underlaps Pyrethroid insecticides are effective at killing young cutworm caterpillars on the leaf and will need to be used if rainfall or irrigation has not occurred in time Effective cutworm control depends on the correct timing of control measures Various cutworm warning services provide timely warnings for control based on day degree accumulation to indicate cutworm development coupled with rainfall irrigation data If rain irrigation has not intervened and 3 instar de
22. r flow particularly immediately after harvest will limit most storage diseases However if celeriac stems have been inoculated via wounds made at harvest the wet flesh will allow the pathogens to develop even if dry air surrounds the stored stem For this reason careful harvesting is a pre requisite for successful disease free storage In the field all these pathogens require host plants on which to multiply and in the absence of a host the pathogen population declines Crop rotation with several years between host crops is a useful means to ensure pathogen populations fail to build up significantly and decline in the intervening years This allows the production of celeriac crops to be sustainable A minimum rotation of one in four years should be implemented if the rotation is composed of crops not susceptible to Sclerotinia If Sclerotinia susceptible crops are the rotation a one in six year rotation is essential with celeriac following a non susceptible crop such as cereals Site pests Free living nematodes of various species are pests of many broad leaved crops If there has been a history of problems of establishment or poor crop performance caused by free living nematodes soil samples should be taken in the previous year for laboratory assessment Selecting fields with a minimal nematode population is a useful cultural technigue to avoid crop damage For carrot fly it is important to be aware of other umbelliferous crops in t
23. resh Produce members This system allows individual growers access to all information for plant protection products approved for use under the Red Tractor Fresh Produce Scheme LIAISON can be accessed under the Produce tab via the Checkers and Services page where you will also find a user manual Searches will be filtered specifically for the crops for which you are registered Once you have logged onto the site and clicked on the LIAISON hyperlink you will be directed to the LIAISON home screen You will need a username and password and these will be sent once you have registered http assurance redtractor org uk rtassurance services Registration members eb General Introduction Following a systematic approach will help growers identify and manage the risks involved in crop production This module is based on a typical crop production process and food safety health amp safety environmental and quality hazards are identified Appropriate controls may then be established to minimise risk Food safety and health amp safety issues always take precedent over quality and environmental controls The layout of this module follows the same structure as that used in the Red Tractor Farm Assurance Fresh Produce Standards The content of the module is reviewed prior to the issue of updated editions The review process considers both new developments and all relevant technology which has emerged since the last review was completed and
24. s to be complete before freezing temperatures occur in the autumn generally early to mid November Sites prone to late spring or early autumn frosts are best avoided Celeriac benefits from irrigation which facilitates steady growth Irrigation is particularly helpful immediately after transplanting to assist establishment In the absence of irrigation water stress may lead to stop start growth with resulting hollow stems If irrigation is not available moisture retentive silt soils are preferred ROTATION Site diseases Celeriac is susceptible to the same range of diseases as celery The following soil borne diseases may build up if celeriac is cropped in a close rotation Grey mould rot Botrytis cinerea licorice rot Mycocentrospora acerina phoma rot Phoma apiicola watery soft rot also called pink rot Sclerotinia minor Jagger and Sclerotinia sclerotiorium Lib de Bary black rot Alternaria radicina crater rot Rhizoctonia solani and fusarium rot Fusarium oxysporum The following diseases persist as spores in crop debris buried in soil Sclerotinia Septoria Spot Septoria apiicola also called Late Blight The following soil borne diseases may attack celeriac during post harvest storage Licorice rot phoma rot Botrytis Pseudomonas spp and Sclerotinia Erwinia spp These pathogens generally need free moisture and or high humidity to develop and express symptoms on produce in store Good ai
25. stance to insecticides It is important to identify which aphid species is present to determine whether a resistance control strategy is appropriate Aphid populations generally increase by females reproducing without mating under suitable conditions populations may increase very rapidly As a general principle good aphid control is obtained by early treatments so regular monitoring to detect aphids and predator presence allows timely decisions to be made Predators are useful in controlling low aphid populations so care needs to be taken to decide if an insecticide is needed at all If it is a selective insecticide should not affect predators that should then control later infestations The following guidelines indicate how insecticide efficacy may be improved In general medium sized droplets work well but if weather conditions permit fine droplets are ideal as these provide better cover of the foliage and increase the probability of direct contact The standard rate of water is 250 ha but heavy aphid infestations require increased water rates up to 500l ha Water rates below 250l ha applied conventionally increase the probability of poor control and need for re application Pyrethroid insecticides are prone to breakdown by ultra violet light so early evening application is preferable as the aphids are likely to be mobile at night and so pick up insecticide more readily Anticolinesterase pesticides should not be mixed unless l
26. trients Any fertiliser applications need to be made on the basis of soil or leaf tissue analyses which enables the correct nutrient to be selected and dose rates appropriately adjusted Information on celeriac nutrition is limited but it is known to be a hungry crop responding well to generous 45t ha farmyard manure applications In the UK celery fertiliser recommendations are generally followed but with adjustments to nitrogen levels following continental European research findings The table in the Appendix giving P K and Mg values originates from the celery section in the Fertiliser Manual RB209 2010 8 Edition It provides a sound base to guide fertiliser recommendations and applications based on assessment of soil samples Soil nitrates must be monitored in the growing season Micro nutrients Celeriac is particularly sensitive to boron deficiency readily producing hollow swollen stems if shortage occurs Boron should be assessed when soil samples are sent for nutrient analysis the following gives a general guide to soil boron availability gelse lt 0 5 mg l severe deficiency treatment essential deficiency likely treatment Telos 1 0 mg l satisfactory for most crops Dutch research recommends a minimum soil boron concentration of 1 4mg l for satisfactory celeriac production Caution is needed as boron is a micronutrient and application levels need to be moderate to avoid reaching toxic levels f
27. utrient shortage are rarely overcome Nutrient assessment The key factor dictating the availability of all nutrients is soilpH so monitoring and adjustment of pH is an essential first step towards good soil nutrient management Macro and micronutrient must be tested by assessing samples of soil or leaf tissue The following table indicates which nutrients are best determined by a soil analysis or leaf tissue analysis Leaf tissue confirmation Soil analysis prediction Soil pH Yes Yes separate testing Phosphate Yes Nitrogen Potassium Yes No use pH texture Yes Yes Not dea Magnesium Sulphur Boron Yes Yes Molybdenum Yes Yes Soil samples should be taken as 25 soil sub samples an auger sample volume is adequate for each sub sample from an area not exceeding four hectares each to 30 and 60cm depth The sub samples the sample should weigh about 1kg should then be sent to a laboratory for nutrient analysis Celeriac is intolerant of acid soil conditions and is sensitive to boron deficiency the optimum pH for celeriac production lies between 6 5 and 7 0 Fields with a wider range of pH values can produce satisfactory crops where supplementary boron fertilisers basal and or foliar are used The cation exchange capacity CEC of the soil is also important i e sands have a low CEC and generally provide a poor supply of boron pH may be less critical where soils have a CEC above 10meq g Major nu
28. velopment has been reached a recommendation to apply insecticide is given The use of this service ensures the use of insecticides is minimised yet effective control is achieved DISEASE CONTROL Celeriac is botanically very similar to celery It is prone to the same range of diseases Some of these diseases become apparent in store rather than in the field Four fungicides are approved Although these are broad spectrum protectant fungicides applications need to be carefully timed to coincide with the onset of infection but before symptoms are expressed As celery and celeriac share many of the same diseases only one of these crops should be grown in the rotation otherwise a rapid build up of mutually infective soil borne diseases may be expected Sclerotinia Sclerotinia is an important disease of a wide range of broad leaved crops The sclerotia are the survival organs and consist of a waterproof tightly enmeshed mass of hyphae Sclerotia may survive for over 20 years in the soil and will grow out to infect a suitable host crop when roots are in close vicinity Susceptible crops include carrots parsnips brassicas vegetables and oilseed rape peas and beans Some broad leaved crops are less susceptible but may still host Sclerotinia e g potatoes and linseed flax Monocotyledonous crops are not susceptible this includes cereals wheat barley triticale etc other graminaceous crops maize and sweet corn and the allium fa
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