Lettuce Best Practice - Department of Primary Industries

Lettuce Best PracticeIntegrated Pest Management

Farm Services VictoriaiiA Guide to Integrated Pest Management for Lettuce- Insect Pest, Disease, Virus, Nematode and Weed ControlEdited by Robert Dimsey, David Carey and Sally-Ann HendersonRob Dimsey, Department of Primary Industries, Bairnsdale, VictoriaDavid Carey, Department of Employment, Economic Development andInnovation (Agri-Science Queensland), Indooroopilly Research Centre.QueenslandSally-Ann Henderson, Sustainability Victoria, Mildura, VictoriaPurpose of this GuideThis guide outlines the key issues that should be considered in relationto the implementation of Integrated Pest Management (IPM) for lettucecrops on a whole of crop basis. The guide addresses the key controlmethods and their rating in an IPM system for the major insect pests,disease, virus, nematode and weed control.The guide should be used in conjunction with the posters; “Lettucecrop protection products – A guide to potential impacts on beneficials”and the “Best Practice IPM – Overview”. The guide should also be usedalongside other publications such as the, “Pests, Beneficials, Diseasesand Disorders in Lettuce – Field Identification Guide”.If you would like to receive this information/publication in anaccessible format (such as large print or audio) please call theCustomer Service Centre on 136 186, TTY 1800 122 969,or email customer.service@dpi.vic.gov.au.Published by the Department of Primary Industries, Farm Services Division,December 2010.© The State of Victoria 2010.This publication is copyright. No part may be reproduced by any processexcept in accordance with the provisions of the Copyright Act 1968.Authorised by the Department of Primary Industries1 Spring Street, Melbourne 3000.ISBN 978-1-74264-593-3 (print)ISBN 978-1-74264-594-0 (online)DisclaimerThis publication may be of assistance to you but the State of Victoria and its employeesdo not guarantee that the publication is without flaw of any kind or is wholly appropriatefor your particular purposes and therefore disclaims all liability for any error, loss or otherconsequence which may arise from you relying on any information in this publication.For more information about DPI go to www.dpi.vic.gov.auor phone the Customer Service Centre on 136 186.

What is IPM (Integrated Pest Management)?IPM is an effective combination of chemical, cultural (such as, farmmanagement practices) and biological methods to keep, weeds, insectpest numbers, disease pressure and other crop production problems lowenough to prevent significant economic loss.In an IPM system the term pest includes insects, diseases, viruses,nematodes and weeds.IPM tacticsGood forward planning and the careful design of a production systemwill minimise the risk of pest, weed and other problems and reduce theneed for chemical control. To implement IPM you must understand:• crop rotation• identification of your best production window• efficient irrigation and drainage systems• monitoring and pest thresholds• beneficials and pests• good farm hygiene• available pest control techniques and products including theirIPM rating.A range of issues must be considered when considering an IPMproduction system:• Identify the main pest and crop issues for the season and timeof production.• If not controlled, do the pests pose a production threat?• Identify the actions required to minimise any potential impact– eg. cultural, crop rotation, variety selection.• Know which pests, diseases and beneficials are in your crop -monitor for beneficials and insect pests and regularly scout yourcrop for any disease incidence.• Understand the pest pressure to determine if control isnecessary.• Identify whether or not there is a threat to production, or thepotential impact, if the pests are not controlled.• Once a decision is made to apply a chemical control, then thechoice of product will depend on the pest to be controlledversus the impact on beneficials, as well as other productionissues.• Record yields and damage to assess effectiveness of controlmethods and review the IPM program.“Beneficials” can be generalist predators such as spiders or more specialised like hoverflies whose larvae prefer to feed on aphids or they may be parasitoidssuch as wasps whose eggs may be laid in pest insect larvae or eggs which are then parasitized by the emerging larvae.Lettuce Best Practice 1

How to monitor/scout a cropThe purpose of scouting/monitoring is to gain a good understandingof insect pest, disease, weed and beneficial insect activity in your crop.Effective monitoring includes assessing the numbers of insect pestsand beneficials in a crop as well as the incidence of diseases andweeds. Recording this information and any control actions taken, willhelp you to better understand your crop management practices overtime. A record of this information, allows you to refer to previousmonitoring results and determine the impact and effectiveness of yourcontrol decisions.Crop monitoringA number of tools are available for monitoring pests and beneficials,including:• Pheromone traps (which attract males of specific pests such as theHeliothis).• Yellow sticky traps (which attract a broad spectrum of flying insects– blue sticky traps can be used for some thrips and leafminers).These tools will help provide information about the range and activityof pests and beneficials present in your crop. Data from traps shouldbe recorded to identify flights, or periods of peak activity. This datawill assist in determining the frequency of crop scouting. Obviously,during peak production periods check traps more frequently. Forexample, if a large flight of moths occurs, then crops should be scoutedat least twice a week during the next few weeks.Forecasting modelsThere are certain forecasting programs which are being developedto assist in determining the likelihood of infection, once suitableconditions are met.For example, there are a disease forecast models for Downy mildewdisease, DownCast and BremCast predictive models are being evaluated.In the future such models can be useful to either trigger a controlaction or indicate the importance of increased scouting and vigilanceover the next few days of a crop’s production cycle.Crop scoutingScouting each area or block regularly, twice a week in warmer weatherand once a week in winter, provides a picture of the beneficials, insectpest, disease, virus and weed levels in a crop. When scouting, covera thorough cross section of a block, as pest problems can occur inpatches at one end or side of a block or at the crop edge. There mayalso be “hot” spots in different areas of a block.Lettuce Best Practice 3

Farm Services Victoria 4The number of plants to check will depend on a crop’s growth stage andthe total area of the planting. Growth stages can be grouped as one ifplantings are close together e.g., group together plantings at two andthree weeks of age.For some pests there are specific recommendations for thresholdsand the number of plants to check. When scouting use a zigzag or Mpattern over a paddock (see diagram for examples) and generally checkat least three plants at a minimum of 10 random sites. There is moredetailed information on scouting patterns in a range of publications onspecific pests.Scouting patternScouting involves moving through paddocks looking for pests andbeneficials, measuring populations and then using this information tomake pest control decisions. The information helps growers know if apest control treatment is needed, where it is needed and what optionsare available and practical. When scouting a crop, it is important toget a random sample using various patterns such as a zigzag, M or Vpattern as indicated below.As you walk through a crop, you are likely to spread infectionparticularly if the leaves are wet. Always scout clean paddocks beforemoving into blocks that are known to be infected and remember topractice good hygiene between crops.Diagram 1: A sample of some scouting patterns.

Farm hygieneGood farm hygiene is one of the simplest, but most often overlooked,methods of managing weeds and pests. Good hygiene reduces the riskof bringing new infections onto the farm, and reduces the spread ofexisting problems.• Production areas of the farm should always have restricted access.• Vehicles and equipment must be cleaned before entering and peopleshould also be made aware of the risk they pose as potential carrierof pests.• Ensure clothing and footwear is clean.• Ensure all people entering the farm report to a central point awayfrom the production zone, such as a shed or office. This includessuppliers, contractors, workers and visitors.• Be sure to explain how to comply with your hygiene practices.• Seedling trays, boxes, crates and other equipment are also a sourceof potential infection and should be inspected before entry.• Only accept clean transplants and ensure they are obtained froma quality nursery who complies with your pest managementstrategies. Avoid using transplants that are infected orcontaminated with pests.If you have your own nursery it should be isolated from crops or hostplants and free of weeds. Use soil-less potting mix, place trays up onbenches, maintain good air movement, control infection and managepests.Internal farm hygiene means avoiding the movement of soil, insectsand plant material around the farm. These can all spread infectionto clean areas. Spread usually occurs via dirty equipment, machinery,vehicles and soil on workers’ boots. Work from young to old plantingsrather than the other way around or if there is a known infection sitebe sure to do that last, whether it is when you are crop scouting,moving a tractor or hand weeding.Keeping headlands clear of weeds is good hygiene practice. It ensuresthere is no place for insects and diseases to carry-over between crops.Clean headlands also reduce weed seed sources contaminating a crop.Removal of crop residues and self-sown plants also forms an importantpart of an efficient IPM hygiene routine as they too can act as habitatfor insect pests and diseases when the main crop has been removed.Note: Weeds may provide habitat for beneficial insects. Therefore youmay need to consider the weeds that are present and the likelihoodthat they may cause production problems and / or be a host for pests.Lettuce Best Practice 5

Farm Services Victoria 6Generic IPM PracticesThere are standard IPM practices that apply to all cropping issues,pests and weed control.A production break: Avoids a weed or pest problem being carried overfrom one season to the next.Land preparation: Good land preparation assists with plantestablishment, weed control and reduces the risk of water logging andplant losses from soil borne diseases.Selecting the right crop and site: Select a crop and production sitethat maximises your chance of success.Keeping records: Records help build a picture of weed and pest riskson different parts of the farm.Crop rotation: To break the life cycle of diseases and pests and controlgerminating weeds.Green manure crops: Improve soil structure, water and nutrientholding capacity, as well as provide a break from intensive production.Green manure crops have the potential to suppress weed growth andmay also act as a harbour for beneficials, but do not let green manurecrops set seed as these can be another weed source.Isolate nursery: A nursery should be isolated from crops or host plantsand free of weeds.Nursery hygiene: Use sterile soil-less potting mix, place trays upon benches, maintain good air movement, control infection andmanage pests.Use only clean healthy transplants: Avoid using transplants that areinfected or contaminated with pests.Post harvest: Destroy old crop residues and weeds promptly byploughing in or spraying off, as these may be a reservoir for pests anddiseases.Subsequent plantings: These should be up-wind (of prevailing winds),where possible, to minimise the chance of contamination. If feasible,put a physical barrier between crops (such as a trap crop, alternatecrop or wind break) so pest and disease problems don’t migrate fromone planting to the next.

Designing the production systemGood farm management practices are vital in the control of pestproblems, such as:• Healthy well-grown plants are less likely to suffer disease andpest problems than plants stressed from poor irrigation and / ornutrition.• Overhead irrigation may, if timed incorrectly, increase the length ofleaf wetness times and hence encourage disease.• Furrow irrigation if timed incorrectly can delay follow-up sprays,which are needed to manage a pest outbreak, and encourage soilborne diseases.• Drip irrigation saves water, allows quick crop re-entry after wateringand doesn’t wet plant leaves.• Bedding-up improves drainage and air circulation around plants –both help reduce disease problems.• Good spray coverage is essential but more difficult to achieve inhigh-density plantings.• Poor air circulation in a crop increases disease risk. Ensure thereis good airflow around plants so the leaves dry quickly and thehumidity doesn’t build up.Production windowThe key is to select a production period and site that will minimiseweeds, insect pest and disease problems. For instance:• caterpillar problems are usually worse in warmer weather• foliar diseases and bacterial head rots are usually worse in warm,wet weather• club root also prefers warm conditions.First select the right variety for a growing season and a particularmarket and then consider options for resistant varieties for insect pestand disease issues.Lettuce Best Practice 7

Farm Services Victoria 8Weed control – pest and beneficial habitatWeeds are a significant host of both pests and diseases in lettucecrops, some specific weeds are known hosts of viruses and the vectorsof those viruses.Weed control and control of pests such as aphids and thrips in weedson headlands may be a necessary management practice for viruscontrol.Weeds that are good hosts of viruses may also be good hosts for arange of pests which transmit the viruses. However, they may also bea good host for beneficials such as parasitoids and predators of thesepests.There can be a conflict in maintaining beneficial habitat and managingthe risk of disease presence and pest activity:• Monitor weeds and remove and control those which are criticalhosts of pests.• Encourage beneficial habitat in areas adjacent to production areasbut not within a crop.• Consider the use of native vegetation or the use of grass species inheadlands as alternative options for beneficial habitat. (For furtherinformation refer to the “Re-Vegetation by Design” project.)It is important to control weeds that are virus hosts as well as pesthosts and green manure crops have the potential to significantlysuppress weed growth.It is vital that a beneficial habitat is encouraged in order to support anIPM program.

The following tables indicate the key control methods, their IPM rating and management for the major insectpests, disease, nematode, virus and weed control issues.Each of the pest areas is colour coded.Insects Disease NematodeSnails and slugs Virus Weed controlLettuce Best Practice 9

Farm Services Victoria 10Effective IPM Rating √ √ √ √ √Critical Comments: There are very good aphid specific and soft options available – seedling drencheswill prevent IPM from being effective.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesMild weather.Spring andautumnplantings.Presence ofsow thistlesin or nearcrop greatlyincreaseschances of sowthistle aphidfeeding onlettuce andtransmittingnecroticyellows virus.Cool /coldweather.Goodpopulation ofbeneficials.Control weedswithin crop andaround crop – arange of weedsare hosts forboth aphidsand viruses(such as mosaicand necroticyellows).A controlthreshold is1-2 aphidsand no sign ofbeneficials onmost seedlingschecked.When scoutingcheck for aphid“mummies”to indicateparasitoidactivity.Monitor usingyellow stickytraps to checkpest levels.Aphids other species excluding CLAIncluding Brown thistle aphid (Uroleucon sonchi), Green sowthistle aphid (Hyperomyzuslactucae), Potato aphid (Macrosiphum euphorbiae), Green peach aphid (Myzus persicae),Foxglove aphid (Aulacorthum solani)Predators:∙∙Spiders∙∙Assassin bugs∙∙Ladybirdbeetles∙∙Lacewings∙∙Damsel bugs(Nabids)∙∙HoverflylarvaeConsiderprovidinghabitat forbeneficialinsects.Plant withspacing thatto allows formaximum airmovement andspray coverage.Neighbouringcrops can be asource of theaphid and thevirus.Select aproductionperiod that willminimise pestpressure.Aphidsreproduceasexually mostof the time somost are clonesof each other.Onceinsecticideresistancedevelops itcan progressquickly.Range oftargetedprotectantand systemicchemicalsavailable.Aphid specificand softoptions areavailable andeffective.Range ofIPM suitableand targetedchemicalsavailable withgood IPMRating.Choosesoft optionproducts whereadditionalcontrol isnecessaryand rotatecorrectly.Seedling drenchapplicationmay haveimpact on thesurvival ofsome beneficialinsects.Broad spectrumproducts reducebeneficialinsect numbers.Because aphidsare vectorsfor a range ofviruses controlis important.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesParasitoids:∙∙Aphid wasps(Aphidiidae)Naturallyoccurring fungican also infectand controlaphid colonies.Aphids aregenerally not aproblem duringcooler weatheronce the cropis establishedCLA can still beactive in coolweather.Evaluate otherpests presentand beneficialswhen decidingon control.Lettuce Best Practice 11

Farm Services Victoria 12Currant lettuce aphid (CLA)Nasonovia ribis-nigriEffective IPM Rating √ √ √ √ √Critical Comments: Use of broad spectrum chemicals can result in increased pest levels – seedlingdrenches will prevent IPM from being effective.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesPrevious ornearby pestpresence.Spring andautumnplantings.Heartinglettuce moresusceptible asaphids colonisewithin theheart.Use of nonresistantvarieties.Colder weatherand frostsmay reduceoccurrence.Resistantvarieties areeffective.Cos typelettuce.Presenceof aphidpredators:∙∙Lacewings∙∙Damsel flies∙∙Ladybirdbeetles∙∙HoverflylarvaePhysicalinspection andscouting isthe preferredmethod ofmonitoring.Yellow stickytraps can alsobe used tomonitor forpresence forbeneficials,however, lesseffective forCLA presence.Destructivemonitoring isrequired oncehearts formed.Predators∙∙Spiders∙∙Assassin bugs∙∙Ladybirdbeetles∙∙Lacewings∙∙Damsel bugs(Nabids)∙∙HoverflylarvaeConsiderprovidinghabitat forbeneficialsadjacent tocropping areas.Plant withspacingthat allowsmaximum spraycoverage.Assesslikelihood ofpest pressureprior toplanting.Select aproductionperiod that willminimise pestpressure.A seedlingdrench hasbeen widelyused as apreventativestrategy forthis pest todate.This is themain aphidthat will infestthe internalheart oflettuce.A seedlingdrench basedon oneinsecticidegroup ishigh risk fordevelopingresistance.A soil /seedlingdrench,followed by arotation with afoliar spray isnow possiblewhere aphidsare observed.Year-roundproductionincreasesthe risk ofinsecticideresistance.Seedling drenchapplicationmay have asecondaryimpact on thesurvival andreproduction ofsome beneficialinsects.Broad spectrumseedling drenchwill preventIPM from beingeffective.Other broadspectrumsprays canknock outbeneficials.Seedlings thathave beentreated in anursery mayadversely affectbeneficials fora few weeks.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesIn spring,these may bemoving aboutin relativelyhigh numbers.Cause forconcern is 3-4aphids andno sign ofbeneficials onmost checkedseedlings.Monitorbeneficials thatare present, asa small numbercan quicklyclear up CLAoutbreaks.Keep recordsof harvestvolume, %damage as wellas numbersof pests tofine tunethresholds.Naturallyoccurringbeneficial fungican infectaphids.CLA can still beproblem duringcooler weatherperiods.Control weedsparticularlyhosts such asHawksbeardand Wildlettuce.IPM techniquesusing naturalpredatorsas a controlmeasure hasbeen effectivein a numberof productionsites.A new highlysystemic foliarspray from anew chemicalgroup, willallow a moreeffectiveinsecticideresistancemanagementstrategy.Effectivesystemicsoft optionaphicides areavailable.Systemicsoft optionaphicides areavailable.Considerusing targetedaphicides foropen headedlettuce ifnecessary.Use of broadspectruminsecticidescan result inpoorer controlof the pest.Lettuce Best Practice 13

Farm Services Victoria 14CutwormAgrotis spp.Effective IPM Rating √ √ √ √ √Critical Comments: Control is best achieved with cultural and management practices, consistent withIPM practices but if chemical control is required it will not fit into an IPM system.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesA nearby cropor a weedyarea could be asource of insectpests.Warm weather.Considerground history.Increased riskif coming outof pasturerotation.Uncultivated orweedy ground.At least oneseason free oflettuce crops.Normally notan issue in anestablishedcroppingarea, thoughoccasionalinfestationscan occur.If the paddockis a knownproblem area,cultivate andhave a fallowperiod beforeplanting acrop.Monitor newlytransplantedseedlings forany sign ofroot or stemdamage.Act quickly tocontrol pest ifit is observed.Active atnight or earlyevening.Parasitoids∙∙TrichogrammaPredators∙∙Spiders∙∙Assassin bugs∙∙Ladybirdbeetles∙∙Lacewings∙∙Predatorybeetles∙∙Commonbrown earwigGood soilpreparation cansignificantlyreducenumbers.Select aproductionperiod that willminimise pestpressure.Controlimportantduring seedlingto hearting.Soil-borneinsect.Control as soonas crop damagedetected.Grounddwellingpest so highwater volumeapplicationessential(minimum600L/Ha).Chemicalcontrol stillrelies on broadspectrumproducts.These are notsuited to IPM.Good spraycoverage isessential asthis is a soildwelling pest.High watervolumes givebest results.Late afternooncontrolapplicationstend to givebest results.Chemicalcontrol canbe difficult toachieve as thepest hides inthe soil.Management isbest achievedwith culturalpractices.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesControl weedgrowth.Look fordamage andcurled upcaterpillars inthe first fewcentimetres ofsoil near plantstems.Early detectionand actionrequired if thepest is present.Plough in cropresidue.Bt could beused late inthe day if eggsare observedon plantsbut needs tobe appliedwhen eggs arehatching.Lettuce Best Practice 15

Farm Services Victoria 16Critical Comments: Monitor crops and use pheromone traps to assess moth activity – need toconsider if corn earworm or native budworm are present as corn earworm has resistance to somechemical groups and broad spectrum chemicals will not provide good control.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesEffective IPM Rating √ √ √ √ √Increases theriskA nearby cropor a weedyarea could be asource of insectpests.Warm weatherincreases therate and speedof hatchingand thedevelopment ofcaterpillars.Pest pressureincreases oversummer.Reduces theriskAt least oneseason free ofhost crops.Healthybeneficialinsectpopulation.Ploughing incrops afterharvest –destroys pupaepreventingemergence.MonitoringControlThresholds1 smallcaterpillarin 20 plants.1 egg in 10plants.Extreme heatwill causeyoung hatchedcaterpillars toquickly moveinto the lettucehead.Moths will layeggs in moresheltered areasof the plant.Heliothis – Corn earworm or Native budwormHelicoverpa armigera or Helicoverpa punctigeraBeneficialInsectsParasitoids∙∙Microplitis spp∙∙Netelia spp∙∙Cotesia spp∙∙Hyposoter spp∙∙Trichogrammaspp∙∙Telenomus spp∙∙Tachinid flyPredators∙∙Spiders∙∙Assassin bugs∙∙Ladybirdbeetles∙∙Lacewings∙∙Predatorywasps∙∙Predatoryshield bugs∙∙BirdsOther Pest Lifecycle Chemical IPM IssuesEnsure goodspray coverage.Good soilpreparation cansignificantlyreduceoverwinteringpupae numbers.Select aproductionperiod that willminimise pestpressure.Controlimportantduringestablishmentto hearting.Control easiestat smallcaterpillarstage.Avoid sprayingat largecaterpillarstage.Active at duskand into thenight.Caterpillarspupate in thesoil.There areregisteredinsecticidesand optionswith good IPMRating.Biologicaloptions toassist controlinclude:∙∙NuclearPolyhedrosisVirus (NPV)∙∙Bacillusthuringiensis(Bt)Year-roundproduction andpoor productrotationincreasesthe risk ofinsecticideresistance.Be awareof whatchemicals havebeen applied tothe seedlingsin the nurseryand how thismight affectbeneficialactivity in thefield.If seedlingdrencheshave beenused thesemay affectbeneficialcontrol of thispest.NPV onlyaffectsHeliothisand no othercaterpillarspecies.Resistance tobroad spectrumchemicals hasbeen recorded incorn earworm.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesVegetable,corn,sunflower,cotton orlucerne cropsnearby or inrotation.Historicalpresence of thepest.Use pheromonetraps for bothH. armigera andH. punctigeraImportant tocommenceregularmonitoringsoon aftertransplantingand prior tohearting.Look foreggs, smalllarvae, feedingdamage, andbeneficialsConsiderprovidinghabitat forbeneficialinsects.Plough in cropresidue to adepth of 10 cmimmediatelyafter harvest todestroy pupae.Bt only workswell againstsmallercaterpillarsso apply itearly in pestlifecycle.NPV (virusproduct) a veryeffective softoption in lowto moderatepest pressuresituations.Hearting toharvest is thecritical periodto monitor andcontrol.Hatchingcaterpillars willquickly tunnelinto headsand are thenuncontrollable.If spraying isrequired closeto harvestuse a productwith a shortwithholdingperiod.Good spraycoverage ismore difficultto achieve onsome varietiesthat tend toheart early.Bt and NPVdo not affectbeneficials.There are newchemistriesmuch lessdisruptive tobeneficialsthan olderbroad spectrumchemistry.Bt stopscaterpillarfeeding buttakes severaldays to kill.Apply Bt’sor NPV afterirrigation notbefore. Avoidthe heat of theday.Lettuce Best Practice 17

Farm Services Victoria 18Loopers and Cluster CaterpillarChysodeixis spp. and Spodoptera lituraEffective IPM Rating √ √ √ √ √Critical Comments: Monitor crops and controls used for Heliothis will generally provide control ofthese species.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesA nearby cropor a weedyarea could be asource of insectpests.Warm weather.Spring thoughto autumn.Early seasonplantings aremost at risk inQLD and WA.Good farm andcrop hygiene.Plough in allweed and cropresidue quickly.1 to 2 eggmasses in 10plants (wait foreggs to hatchbefore takingaction).∙∙Prefer outerand wrapperleaves.Monitorcrops prior tohearting.Parasitoids∙∙Microplitis spp∙∙Netelia spp∙∙Cotesia spp∙∙Trichogrammaspp∙∙Telenomus spp∙∙Tachinid flyPredators∙∙Spiders∙∙Assassin bugs∙∙Ladybirdbeetles∙∙Lacewings∙∙Predatorywasps∙∙Predatoryshield bugs∙∙BirdsPlant withspacing thatallows formaximum spraycoverage.Rotate crops tominimise pestpressure.Select aproductionperiod that willminimise pestpressure.Control easiestat smallcaterpillarstage.Avoid sprayingat largecaterpillarstage.Hearting toharvest is thecritical periodto monitor andcontrol.There areregisteredsystemic andprotectantinsecticidesand optionswith good IPMRating.Bacillusthuringiensis(Bt) onlyworks wellagainst smallcaterpillars;apply itearly in croplifecycle.Be aware ofwhat chemicalshave beenapplied to theseedlings inthe nursery.Bt stopscaterpillarfeeding buttakes severaldays to kill.Bt doesnot affectbeneficials.Apply Bt’s afterirrigation notbefore. Avoidthe heat of theday.If seedlingdrencheshave beenused thesemay affectbeneficialcontrol of thispest.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesConsiderprovidinghabitat forbeneficialinsects, lizards,birds, frogs.Encouragebeneficialinsects andprovide insectrefuge areaswhere possible.Plough in cropresidue.If spraying isrequired closeto harvestuse productwith a shortwithholdingperiod.There are newchemistriesthat are lessdisruptivethan olderbroad spectrumchemistry.Beneficials canimpact on pestpopulations ifcrop managedcorrectly.Lettuce Best Practice 19

Farm Services Victoria 20Effective IPM Rating √ √ √ √ √Critical Comments: Some chemicals are not suited to IPM. Choose chemicals carefully as not allspecies are controlled by soft products – RGB has no IPM suitable chemistry..Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesWarm, dryweather.Some varietiesmay be moreattractive.A nearby cropor a weedyarea could be asource of thripsor Rutherglenbug.Cool /coldweather.Control weeds.Consider theuse of trapcrops for RGB.Yellow or bluesticky trapscan be used tomonitor thrips.Monitor forflights ofmigratingRutherglenbug.Not all thripsare pestspecies.Pest speciesoften moveon prevailingwinds insummer.Sucking pestsThrips spp. (several species Onion thrips - Thrips tabaci, Tomato thrips -Frankliniella schultzei) and Rutherglen bug (RGB)- Nysius vinitorPredators∙∙Spiders∙∙Ladybirdbeetle∙∙Lacewinglarvae∙∙PredatorythripsSome predatorymites andbeetlesRGB is notknown to haveany predatorsin lettuce.Ensure goodspray coverage.Select aproductionperiod that willminimise pestpressure.Consider usingscreening meshin nursery areaif pest pressureis high.Controlimportantfrom seedlingproduction toharvest.Pests mainlymigrate intothe crop onprevailingwinds.RGB moves toirrigated cropsin very hot dryconditions.RGB doesnot breed inlettuce.Lifecycle isquicker in warmweather.Rotatechemicalgroups to avoidresistance.For thrips rangeof chemicalsavailable andsome are agood IPMRating. Choosesoft optionproducts whereavailable.Year-roundproduction andpoor productrotationincreasesthe risk ofinsecticideresistance.Soft optionproductsavailable forsome thrips butnot all speciesare controlled.Onion thrips,tomato thripscan spreadviruses such asTomato SpottedWilt Virus(TSWV). Seeentry for WFTBeneficialhabitat mayalso hostthrips.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesConsiderprovidinghabitat forbeneficialinsects.Immediatelyafter harvest,spray-offor cultivateand ploughin lettuce todestroy cropresidue.For RGB controlthere are onlybroad spectrumchemicalsavailable atthis timethough someof the newersystemicproducts maybe effective.Remove anyvirus infectedplants / weedsto minimisere-infectionpotential.RGB are verymobile andif chemicalcontrol isapplied theycan quicklyre-infest acrop.Need toconsiderif controlis actuallyrequired.Lettuce Best Practice 21

Farm Services Victoria 22Critical Comments: Seedling drenches can affect beneficials and affect IPM. WFT is a critical vectorfor Tomato spotted wilt virus (TSWV) and where both are found, an integrated management approachis critical.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesEffective IPM Rating √ √ √ √ √Increases theriskConsiderweatherconditions andsurroundingcrops and weedhosts.Warm weatherincreases thripsnumbers.Reduces theriskNursery fullyinsect-screened(thrips-proofscreen) anddouble doorsprevent insectentry.Ensuretransplants arefree of pest.Control weedsin crop andheadlands.MonitoringControlThresholdsYellow or bluesticky trapsshould be usedin coveredsystems andcan be usefulin field crops.Visuallymonitor cropfor thripsnumbersand virussymptoms.Virus-infectedplants shouldbe physicallyremoved anddestroyed.Western Flower Thrips (WFT)Frankliniella occidentalisBeneficialInsectsImportant toensure goodspray coverage.Immediatelyafter harvestspray off orcultivateand ploughin lettuce todestroy cropresidue.Other Pest Lifecycle Chemical IPM IssuesSoil predatorymites∙∙Predatorythrips∙∙SomepredatorybeetlesBeneficialpredators arecommerciallyavailable.Lifecycle isquicker in warmweather.The fulllifecycle can becompleted inas little as 10days at 20°C.Sprays onlyeffectiveagainst certainlifecyclestages. Goodhygiene in andaround thecrop minimisespest pressure.The seedlingdrench forCurrant lettuceaphid willcontrol somethrips speciesbut not WFT.Use a rangeof chemicalgroups toreduce thechance ofresistanceDifficult toidentify withthe naked eyefrom otherthrips.WFT hasshown itselfto be quickto developinsecticideresistance.Spinosadresistantpopulationsexist in someproductionareas.Can spreadTomato SpottedWilt Virus(TSWV).Insecticidalseedlingdrenchescan affectbeneficialinsects andaffect an IPMprogram.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesSurroundingweeds andother crops(e.g. tomatoor floweringcrops) canbe a sourceof WFT andmay increasethe risk ofa residentresistantpopulation.Previous plantvirus infectionof crops maymake controlmore critical.Hygiene andend of cropclean-upcritical.Some newchemistry isclaimed tobe soft onbeneficials.Lettuce Best Practice 23

Farm Services Victoria 24Effective IPM Rating √ √ √ √ √WhitefliesSilverleaf whitefly (SLW) Bemisia tabaci (Biotype b), Glasshouse whiteflyTrialeurodes vaporariorumCritical Comments: No chemicals registered for control in lettuce but some used for othersucking insects will provide control. Pest does not breed on Lettuce. The two Whitefly species lookvery similar.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskHot conditions.Nearby Whiteflyhost crops orweeds.Poor hygienein protectedcroppingstructures.Reduces theriskScreen nurseryif necessary.Double doorson protectedcroppingstructures.Keep crop areaweed free.Effectivemonitoring.MonitoringControlThresholdsMonitor forpresence /damage. Yellowsticky trapscan be usedto monitor forWhitefly.2-4 flies perleaf present on40% of plants.Correctlyidentify theWhitefly todetermineits potentialimpact.BeneficialInsectsWaspparasitoidsattack SLWnymphs.GeneralistPredators.Considerprovidinghabitat forbeneficials.Other Pest Lifecycle Chemical IPM IssuesEnsure goodspray coverage.Select aproductionperiod that willminimise pestpressure.Harvestingof nearbysusceptiblecrops maycause Whiteflyto migrate toyour crop.Spray oils andeven wettersknock-downadults.Whitefly doesnot breed onlettuce.Adult Whitefliesdamage lettucecrops.There arelimitedchemicalsavailable forcontrol.Year-roundproduction andpoor productrotationincreasesthe risk ofinsecticideresistance.Crops that hostSLW and aresprayed withbroad spectruminsecticideswill see a largepopulationincrease.Some chemicalcontrols forother suckinginsects onlettuce willprovide control.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM IssuesriskriskControlThresholdsInsectsGenerallyan issue toseedlings andtransplants.Lettuce Best Practice 25

Farm Services Victoria 26Wireworm / False WirewormElateridae spp. / Tenebrionidae spp.Effective IPM Rating √ √ √ √ √Critical Comments: Control is best achieved with cultural and management practices, consistent withIPM practices but if chemical control is required it will not fit into an IPM system.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesStubbleretention andtrash fromprevious crop.A nearby cropor a weedyarea could be asource of insectpests.Considerground history.Increased riskif coming outof pastureor lucernerotation.If followingpasture orknown problempaddockcultivateseveral weeksbefore plantingand considerperiod of fallowNormally notan issue in anestablishedcrop.Monitor newlytransplantedcrop.Look fordamaged(missing,wilted)seedlings andthen search fordamaged rootsand wirewormsin soil aroundthe plant.Act quickly tocontrol pest ifit is observed.∙∙Commonbrown earwig∙∙PredatorygroundbeetlesConsiderprovidinghabitat forbeneficials.Good soilpreparation cansignificantlyreducenumbers.Controlimportantduring seedlingestablishment.Soil-borneinsect.Control as soonas crop damagedetected.Grounddwellingpest so highwater volumeapplicationessential(600L/Ha).There areregisteredinsecticides butnot a suited toIPM.Chemicalcontrol stillrelies on broadspectrumproducts, whichare not are nota good IPMRating.High watervolumes givebest results.Late afternooncontrolapplicationstend to givebest results.Chemicalcontrol canbe difficult toachieve as thepest hides inthe soil.Managementbest achievedwith culturalpractices.

Farm Services Victoria 28AnthracnoseMicrodochium panattonianumEffective IPM Rating √ √ √ √ √ResistantvarietiesavailableCritical Comments: Monitor crops to assess need for control and when conditions suitablefor infection start protection program.Rotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakIf weatherconditionsfavourdisease,Anthracnosecan causehigh croplosses.Cool and wetconditionsin autumnsor especiallylate winter toearly spring.Optimumtemperature18 ˚C - 20˚C.Can survive insoil for up to4 years.Host specificto lettuce sorotate withany othernon-hostcrop.Avoidplanting inpaddockswith ahistory of thedisease.Control hostweeds.Well-grownplants witha balancednutritionprogramare lesssusceptible.Minimiseperiods ofextended leafwetness.Use irrigationsystems thatreduce oreliminate leafwetting.Water splashcan spreadthe disease.Only usedisease-freeseedlings.Rotate withnon-hostcrops toreduce levelsof pathogenin soil.Symptomscan appear4-8 days afterinfection.Spray off orplough inharvestedareas as soonas possibleafter harvest.A preventativemonitoringand fungicidalprogram(protectants)should beemployed toprevent earlyinfection ifa problem isexpected.Systemicchemicals areavailable butpreventionis moreeffective.Infectionmay occur atthe seedlingproductionphase – donot overirrigate.Monitorclosely whenconditionsfavourinfection.

ResistantvarietiesavailableRotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakFields with ahistory of thedisease.Cos (Romaine)lettucecultivarsappear tobe moresusceptiblethan icebergor loose leafvarieties.Host weedssuch aswild lettuceor pricklylettuce.Irrigationtimingimportant as2-4 hours ofleaf wetnesscan resultin infectionwhen thefungus ispresent.Need toconsiderchemicalresistancemanagement.Protectivecopperfungicideswill assistin diseaseprevention.Lettuce Best Practice 29

Farm Services Victoria 30Botrytis (grey mould)Botrytis cinereaEffective IPM Rating √ √ √ √ √Critical Comments: Monitor crops to assess need for control.ResistantvarietiesavailableRotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakDamagedseedlings.Romainetypes are verysusceptible.Highhumidity.Botrytisis usuallya minorproblem.Rotate outof lettuce asthe funguscan survivein debris,soil and onalternativehosts.Botrytis hasa wide hostrange.Oftenfollows otherdiseases intoa crop.Seedlingscan be killedif infectedearly in theseason.Excessnitrogen(N) and lowCalcium (Ca)favour thedisease.Free moistureis needed forinfection.Avoid longperiods ofleaf wetness.Irrigate earlyin the day sofoliage candry as quicklyas possible.Avoidoverheadirrigation ifpossible.Maximiseventilation.Minimizeplant debris.Avoidplantingoversizetransplants asleaf damagemay occurduring theplantingprocess andthis may leadto infection.Botrytisinfectsdamagedtissue.Spread on aircurrents soplant up-windof old crops.Botrytis doesnot infecthealthy greentissue unlessan injury ordead area ispresent.Alwaysspray-off orplough incrop residueimmediatelyafter harvest.Manyfungicidesare effectiveagainst graymould. Thefungicides arepreventativeand shouldbe appliedbeforeinfectionoccurs.Copperapplicationswill havesomepreventativeeffect.Need tobalancerisk andmanagementfor tipburnwith riskof Botrytis.Nightwatering ispreferredfor tipburncontrol.In hotweather leafwetnessshould not bea problem.

ResistantvarietiesavailableRotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakIf weatherconditions arefavourable forthe pathogenthen greymouldcan causesubstantialcrop loss inboth greenhouse andfield lettuce.Minimisedamagecaused byseedlinghandlingin nursery,culturalpractices,and otherpathogensand pests.All fungicidesused forSclerotiniacontrol arealso effectiveagainstBotrytis.Rotatefungicidegroupsto avoidresistance.If there is aconflict indisease andtipburn riskirrigate veryearly in theday.Lettuce Best Practice 31

Farm Services Victoria 32Downy MildewBremia latucaeEffective IPM Rating √ √ √ √ √ResistantvarietiesavailableThere aremany types(or races) ofthis fungus.Some lettucevarietiesclaimresistance tosome racesCritical Comments: Use resistant varieties and monitor crops closely and apply protectivemeasures when conditions suitable for infection.Rotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakCool, dampconditions.Free moistureon plantleaves.High riskfollowinglettuce crops,near globeartichoke,endive,chicory andornamentalhost plants.Seed shouldbe fungicidetreated.Avoidplantingnear otherlettuce fieldsas airbornespores canbe dispersedfrom one cropto the otherby the wind.Crop rotationis important.ExcessiveNitrogenmay makelettuce moresusceptible.Avoid highnitrogenlevels.Avoidwateringseedlingsfrom 8.00am-12.00pm asmost sporesare releasedduring thisperiod,irrigation willact to washspores out ofthe air andprovide wetleaf surfacesfor them toinfect plants.Use widerplant spacingto facilitatebetter airmovementand leafdrying.Transplantsshould beprotectedwithfungicides toavoid Downymildew beingintroducedinto the field.Predictivemodels fordowny mildewon lettuceare underevaluationworld-wide.Align plantspacing thatallows formaximumventilation.Subsequentplantingsshould beup- wind ofcurrent crops.Applypreventativefungicidesbefore thediseasedevelopsbased onweatherconditions.Rotate withcurativefungicideswhenconditionsare ideal forinfection.Chooseresistantvarietieswherepossible.More difficultto controlas the plantages andcrop densityincreases.Control mayconflict withoptimumirrigationtiming duringthe nightfor tipburnmanagement.

ResistantvarietiesavailableRotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakCrop residuesshouldbe fullydecomposed(brokendown) beforeplanting anew crop.Spray-off orplough inharvestedareas as soonas possibleafter harvest.Preventativeactionrequired ifyou havea historyof diseaseoccurrence.Good culturalpractices andmanagementprovides bestcontrol.Rotatecrops withnon-hosts toreduce theinoculum butthis diseasehas a widehost range.Lettuce Best Practice 35

Farm Services Victoria 36Sclerotinia (lettuce drop)Sclerotinia sclerotiorum and Sclerotinia minorCritical Comments: IPM is the most effective control, use of fungicides is not a sustainablelong-term measure, management and cultural practices are essential. Identification of theSclerotinia pest is essential to determine the most effective control methods.Rotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakEffective IPM Rating √ √ √ √ √ResistantvarietiesavailableNoneavailable.Cool, humidspringautumnweather.Wet soil.Followingothersusceptiblecrops.The pathogencan surviveas Sclerotiain soil for5 years ormore.Broadhost rangeincludingsome greenmanure orbreak crops.Cereals andgrasses arenon-host andthus goodrotationcrops.Soilamendmentswith highNitrogen suchas poultrymanurecan reducesurvival ofSclerotia insoil.Improve soilstructure toreduce waterlogging.Use raisedbeds ifneeded.Avoidboth overand underwatering tomaintainconsistentsoil moisturelevels.Effectiveirrigationscheduling isessential.Minimisespread ofdisease bycleaningequipmentafter usein infectedpaddocks.Devise aproductionsystemsthat reducesthe risk ofSclerotiniaoutbreaks by:∙∙Usingpracticaland costeffectiveculturalpractices.∙∙Implementinga rotationprogramthatincludesnon-hostcrops.In fieldswith historyof S. minorlettuce drop,protectantfungicidesappliedsoon aftertransplantingcan reducediseaseincidence.Applicationmust be tothe base ofseedlingsand repeatedbefore plantsbecome toolarge.Use gooddrainage,culturalpractices andcrop rotation.The biocontrolagentC. minitanscan reduceinfectionscaused byF. sclerotiorum.An IPMapproachis the bestto manageSclerotinia.Chemicalcontrol is notsustainable inthe long-term.Control oflettuce dropcaused by S.sclerotiorumis difficultbecauseairborne sporescan enter thelettuce fields atunpredictabletimes.

Farm Services Victoria 38Septoria spotSeptoria lactucaeEffective IPM Rating √ √ √ √ √ResistantvarietiesavailableCritical Comments: Monitor crops to assess need for control and start protection programwhen conditions are suitable for infection.Rotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakPrefersprolongedperiods ofhigh humidityand cool,wet windyconditions.Severeinfection canrender cropsunmarketable.Fields with ahistory of thedisease.Avoidplantinglettuce infields witha history ofdisease.Control hostweeds.Crops understressare moresusceptible.Water splashmovesinfectiononto leaves.Minimiseperiods ofextended leafwetness.Use irrigationsystems thatreduce oreliminate leafwetting.Only usedisease freeseedlings.Keepseedlingsdiseasefree withprotectantfungicides.Diseasenormallyappears onthe olderlower leavesfirst.Rotate withnon-hostcrops toreduce levelsof pathogenin soil.Spread bywet windyconditions,older leavesaffected first.Apreventativemonitoringand fungicidalprogram(protectants)should beemployed ifconditions aresuitable toprevent earlyinfection.Systemicchemicals areavailable butpreventionis moreeffective.Hygieneon farm isimportant,destroy oldcrop residues.Infectedplants area majorsource ofnew diseaseoutbreaks.Monitorclosely whenconditionsfavourinfection.

ResistantvarietiesavailableRotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Nutrition Irrigation Hygiene Other Chemical IPM IssuesBreakHost weedssuch aswild lettuceor pricklylettuce.Spray-off orplough inharvestedareas as soonas possibleafter harvest.Lettuce Best Practice 39

Farm Services Victoria 40NematodesMeloidogyne spp. and Pratylenchus spp.Effective IPM Rating √ √ √ √ √ResistantvarietiesCritical Comments: Effective long-term control will be only be provided bymanagement and cultural practices..Rotation Crop Cultural Practices Chemical Control Conflicts /IssuesHigh Risk Disease Break Nutrition and Hygiene Other Chemical IPM IssuesIrrigationAvoid plantingNematicidesin fields withare registered‘high’ RKN orfor use in someRLN numbers.states.Sandy soils area higher riskfor RKN.Crop rotationwith non-hostsof 1-2 yearsis generallysufficient toreduce RKNnumbers tonon-damaginglevels.Some varietiesof cereals,grasses andsorghum arenon-hosts orpoor hostsfor RKN andcan be grownprior to thecrop to reducenematodenumbers.Nematodes“swim”therefore avoidwet soil forlong periodsto reduce theirspread.Avoid overoverwateringby schedulingirrigationappropriatelyand ensureadequatenutrition.Nematodes aremoved on soiland machineryso hygiene isimportant forcontrol.Always workinfestedpaddocks lastand cleanmachineryafter workingin infestedpaddocks.Roots ofstunted plantsshould beexamined forgalling causedby RKN.A pre-plantsoil test shouldbe done todeterminenematodenumbers in afield if gallingis evident,a problemis suspectedor there isa history ofnematodes.General soilfumigants suchas methamsodium preplantingwillalso providecontrol ofnematodes.Soilsolarisationusing plasticfilm prior toplanting maybe costeffectivein somesituations.Growing andincorporatinga biofumigantcrop prior toplanting mayalso providecontrol.Chemicalcontrol will notbe compatiblewith IPMpractices.Note that somebiofumigantsare good hostsof nematodes(e.g., RKN).

Farm Services Victoria 42Slugs and SnailsMolluscaEffective IPM Rating √ √ √ √ √Critical Comments: Control is best achieved with cultural and management practices.Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases theriskReduces theriskMonitoringControlThresholdsBeneficialInsectsOther Pest Lifecycle Chemical IPM IssuesA nearby crop,drain, dam ora weedy areaor headlandscould be asource of slugsand snails.Long grass indrains.Following apasture crop.Minimumtillage.Wet weather.A physicalbarrier ofempty landbetween cropsand waterwaysand drainshelps slow pestmovement tothe crop.Good croprotation.Keep cropblocks 3m - 4maway fromdrains anddams.Check cropcanopy andplant centres inareas adjacentto drains andwet spots,slugs and snailtend to appearthere first.Larger plantsare generallyless affectedbut slugs andsnails can be acontaminationpest.∙∙Birds∙∙Lizards∙∙Other smallvertebrates∙∙CarabidbeetlesGood soilpreparation cansignificantlyreducenumbers.Fallow periods.Improveddrainage andimproving soilquality assistscontrol.Drip irrigationreducesoccurrence.Plants arevulnerablewhen small.Cool moistenvironmentsand areasfavour pestsurvival andoverwintering.Onceestablishedpest cansurvive in thesoil betweencrops unlessthe life cycle isbroken.No registeredchemicalsavailable forcontrol withinthe crop.Drains, dampareas thatadjoin the cropcan be baited.A protectiveborder can beused to preventpest movementinto the crop.Need to controlin borders andheadlands andbait thoseareas if aproblem islikely.Baits or abarrier striparound theaffected croparea.Totally relianton managementpractices.

Infestation Risk Factors Cultural Practices Chemical Control Conflicts /IssuesIncreases the Reduces the Monitoring Beneficial Other Pest Lifecycle Chemical IPM IssuesriskriskControlThresholdsInsectsPlough in cropresidue.Remove debristhat can beused as shelterareas and keepgrass short.Lettuce Best Practice 43

Farm Services Victoria 44Effective IPM Rating √ √ √ √ √How is ittransmitted?Host plantsLBVDCucumber mosaicvirus (CMV)The virus istransmitted by morethan 60 species ofaphid, including:∙∙Acyrthosiphonpisum∙∙Aphis crayccivoraand∙∙Myzus persicaein a nonpersistent**mannerA very wide hostrange including:∙∙Lettuce∙∙Vegetables∙∙Weeds∙∙Ornamentalspecies.VirusIPM Control - Pre Plant Planning.Critical Comments: Vector and weed control is critical to virus management – the IPM Rating will depend onchemicals used for vector control..Lettuce mosaicvirus (LMV)Seed-borne inlettuce seed andmost outbreakscan be traced toinfected seed lots.Also spread byaphids (Aphisgosseii, Macrosiphumeuphorbiae, Myzuspersicae in anon-persistent**manner).The virus has a widehost range includingthe weeds, thistles(Sonchus spp) andFat hen.Turnip mosaic virus(TuMV)The virus istransmitted by morethan 50 species ofaphid, includingMyzus persicaeand Brevicorynebrassicae, in anon-persistent**manner.Wide host rangeincluding:∙∙Lettuce∙∙Vegetable brassicas∙∙Canola∙∙Brassica weeds∙∙other weed species.Lettuce necroticyellows virus(LNYV)Transmitted by onlyone aphid species,the Sow thistleaphid (Hyperomyzuslactucae) in apersistent* manner.Both the virus andaphid have sowthistle as theirmajor host.Tomato spottedwilt virus (TSWV)Spread by severalspecies of thrips:∙∙Thrips tabaci∙∙Frankliniellaschultzei∙∙F. occidentalis(Western FlowerThirps)A very wide hostrange amongcrop, weed andornamental species.Lettuce oftenseriously affected.Lettuce big veindisease (LBVD).(Mirafiori lettucevirus/lettuce bigvein virus)The viruses causingthe disease aretransmitted by thesoil-borne fungusOlpidium virulentus.The virus survivesin the fungal restingspore which canremain viable in soilfor several years.The disease isfavoured by coolweather and wetsoils.

Host plantscontinuedKey controlinformationCucumber mosaicvirus (CMV)Remove old cropsand weed control inand around the cropis essential.Insecticides maycause more harmthan good as theirapplication mayencourage the aphidto move from plantto plant.Potentially, CMV willthen be transmittedto each plant visitedby the aphid.Lettuce mosaicvirus (LMV)Weed control aroundand in the crop isessential.It is critical to plantLMV-tested seed.Turnip mosaic virus(TuMV)An occasional issuewhere lettuce isgrown near infectedbrassica crops ornear infected weeds,particularly weedybrassica species.Weed control aroundand in the crop isessential.Incidence of TuMVmay increase wherelettuce is grownnear infectedbrassica crops orweeds (particularlybrassica species).Lettuce necroticyellows virus(LNYV)Weed control,particularly forSow thistle, aroundand in the crop isessential.Tomato spottedwilt virus (TSWV)Weed control aroundand in the crop isessential.Lettuce big veindisease (LBVD).(Mirafiori lettucevirus/lettuce bigvein virus)As the fungus issoil-borne thedisease is difficultto control.It is importantto plant healthyseedlings.Crop rotations canreduce the diseaseincidence.* Persistent – Aphids need to feed for an extended period of time on each host to pick up and then transmit the virus from one host to another.** Non- persistent – Aphids only need to feed for a very short period of time on each host to pick up and transmit the virus from one host to another.Several of the above viruses produce similar symptoms in lettuce and are difficult to separate in the field. Laboratory tests are often necessary todetermine which virus or viruses are present.Lettuce Best Practice 45

LNYVFarm Services Victoria 46Virus minimisation strategyPre-plantNurseryTransplant through tovegetative growthRotations out of lettuce will help reduce big vein disease incidence.It is essential to control weeds in and around production areas.Collectively, the viruses infecting lettuce have a very wide range of potential hosts so a thorough weedmanagement program is recommended, rather than selecting individual species which may be common hosts.Purchase seed and seedlings from reliable suppliers and ensure that it has been tested for Lettuce mosaic virus(LMV) freedom.Consider LBVD tolerant varieties when growing during cool weather in areas with a history of the disease.If aphid-transmitted viruses are an ongoing issue (CMV, LMV and TuMV) consider the use of permanent wind rowsand strategic planting to maximise the distance between lettuce crops.Ensure nursery area is free of weeds.Control insect vectors-thrips, aphids.Where possible locate nursery in a district remote from production areas.Maintain weed control in and around production areas, especially of virus host plants.Monitor for and maintain good management of insect vectors.Avoid planting new crops near old crops, particularly where virus and other diseases have been prevalent.Remove any virus affected plants from the crop area to minimise virus spread.It is important to control the insect vectors (see control methods for insect vectors) before virus is observed in thefield.

Transplant through tovegetative growthcontinuedHearting through to harvestOnce virus is present in a crop, it is too late to eradicate the virus and attempts to control aphid vectors atthis point can further spread virus in the crop for diseases such as CMV and LMV, due to the method of virustransmission.It is important to reduce virus spread to subsequent crops.Avoid planting near affected crops and plant upwind.Have non-host crops as alternate plantings.Monitor crops closely for insect vectors and symptoms but if the virus is observed in the last stages of cropgrowth, there will be a minimal affect on yield.Destroy harvested crops promptly.Do not plant new crops close to old crops.Plan to have fallow land or non-susceptible crops as a means of separating plantings.Remove any virus-affected plants from the crop area to minimise virus spread to other plants, particularly youngerplantings that are nearby.Plant upwind of affected crops if possible.Have non-host crops as part of your crop rotation.Lettuce Best Practice 47

Farm Services Victoria 48WeedsIPM ControlEffective IPM Rating √ √ √ √ √Method of control for aweed free seedbedPre-plantBed formation before plantingCritical Comments: Weed control is an essential component of IPM for a range of pest issues. It is essential toconsider the range of potential host plants for key diseases and their vectors as well as problem, insect pests.How to do it Negatives PositivesForm beds well before planting and then irrigateto germinate an initial flush of weeds.Kill these weeds by spraying with a knockdownherbicide.Alternatively, kill weeds with a very shallowcultivation.For organic farming, flaming, steam or hotwater treatments are alternatives to knockdownherbicides.Green manure crops can suppress weed growth.Form beds just before planting, with a finalcultivation to prepare the seedbed and kill anyemerged weeds.If high weed numbers likely form beds wellbefore planting and spray-off emergingweeds before planting or pre-plant herbicideapplication.Avoid moderate to deepcultivations because theywill cause more weeds togerminate in the crop.Not the preferred option inpaddocks with substantialnumbers of weeds.A range of techniquescan be used to kill off thegerminating weeds.Reduces weed numbers beforeplanting.

Method of control for aweed free seedbedFumigationHow to do it Negatives PositivesForm beds before planting, then fumigate,(refer to fumigant labels for specific rates).Fumigating or “gassing” can produce variableresults depending on a number of factorsincluding soil type and temperature, moisturecontent, and exposure time. Contractors withspecialist application equipment operate in manyproduction areas.Incorrect soil moisture willreduce the effectiveness offumigation.Expensive and results can bevariable.Fumigation will also kill offbeneficial soil organisms.This is not an IPM friendlypractice.Fumigation has the additionalbenefit of controlling somediseases, nematodes andinsect pests, depending onpest severity and the ratesused.Control using mulchIn combination with drip irrigation, lay plasticor paper mulch to control weeds and thentransplant through this much layer.To make the most of the costs associated withthis system growers usually try and replant thesemulched beds with a second rotation crop.Plant based plastic type mulches claiming to bebiodegradable are also now being developed andsold in some areas.It is too early to know how well these productsperform in different environments, how well theybreak down and whether they are in fact moreenvironmentally friendly than traditional plasticproducts.Cannot be used withoverheard irrigation.In summer production areasexcess soil heat generatedby plastic mulch can causeproduction issues.Can be expensive and moredifficult to manage.May increase soil temperaturefor an increased plantingwindow.Lettuce Best Practice 49

Farm Services Victoria 50WeedsIPM ControlWeed management is a significant proportion (about 20%) of pre-harvest variable costs in lettuce production. Poorly managed or ineffectiveweed control can be even more costly as it impacts on disease severity, harvest weight, heart size and adds to weed potential in following crops.Weed control is an essential component for IPM for a range of pest and disease issues. Weeds can also act as a reservoir for beneficials soconsideration must be given the weeds present and the risks they may be to crop production. Plants or vegetation that are not a host to diseasesor pests may help support a beneficial population.Site selection and preparationIt is extremely difficult to grow lettuce in land with large weed seed banks; pre-planting management is the key to success. Land with at least atwo-year history of effective weed control achieved by selective crop rotation and cover cropping is best.Weed management in the lettuce crop starts with planting into a weed-free seedbed. There are a few possible options for achieving this.

Broadleaf weedsThe most significant weed problem. Particularly the Asteraceae (daisy-type) family (Potato weed and Commonsow thistle).Whilst late-emerging weeds may not affect lettuce yields they should still be managed. Species such as potatoweed can grow dramatically in the last few weeks before harvest and interfere with cutting and packingprocesses. In an integrated weed management program, it is important to minimise the populations ofweeds setting seed. It may make economic sense to selectively hand-weed in the weeks before harvesting,particularly if weed seed development can be prevented.There are herbicides registered for broadleaf weed management. They must be applied just before, at, orimmediately after planting, before weeds have emerged. They will not kill established weeds.Choosing which herbicide to use will depend on several factors including which weed species is likely to bea problem, what you plan as the following crop in the rotation, and the types of herbicides used in previouscrops.To avoid the build-up of resistant weeds, it is important not to continuously use herbicides with the samemodes of action.Some chemicals can only be used before transplanting.Some chemicals can be applied directly after seeding or transplanting, and then irrigated in.It is essential to minimise the time between final cultivation (or knockdown herbicide application) andspraying pre-emergent herbicides. The longer the delay (eg. more than 2 to 3 days), the more likely it is thatnew weeds will germinate and not be controlled by the chemicals.Closer to harvest broadleaf weeds in the lettuce crop can only be killed by cultivation or hand weeding.Grass weedsSeldom a problem. Most will be controlledby the same cultural practices used tomanage broadleaf weeds.There are pre-emergence herbicidesto control many grass species beforeemergence.There are registered chemicals for postemergencegrass control in lettuce.Lettuce Best Practice 51

Farm Services Victoria 52WeedsPost harvestRotation Crop Cultural Practices Conflicts / IssuesHigh Risk Disease Break Nutrition andIrrigationAreas with a previoushistory of weeds.Areas planted besideweedy areas.Troublesome weedssuch as nut grass(Cyperus rotundus) orpotato weed (Galinsogaparviflora), are difficultto control.A consistent systemof crop rotation andweed control betweencrops will minimiseweed build up prior toplanting.Because of residualactivity, sensitive crops(e.g. beets) should notbe sown immediatelyfollowing a lettucecrop treated with somechemicals. Refer to thelabel for re-croppingintervals.Some chemicals mustbe applied beforetransplanting.HygieneNursery and farmhygiene are importantfactors in bothminimising weedpopulation.Farm-based nurseryproduction facilitiesshould be kept weedfreeand well drained.OtherTo maintain an effectiveherbicide blanket, itis also important thatcultural operations afterherbicides are applied,e.g. while transplantingminimise soil surfacedisturbance.Whilst late-emergingweeds may notaffect lettuce yieldsthey should still bemanaged. Species suchas potato weed cangrow dramatically in thelast few weeks beforeharvest and interferewith cutting andpacking processes.Take care on sandysoils, as the highestherbicide rates maycause crop stunting andyield reduction.The Queenslandexperience found insome circumstances(high temperaturesand sandy soils), cropdamage can occur.Growers unfamiliar witha product are stronglyadvised to only treata small area at first,to determine productperformance with localsoils, climate andvarieties.

Rotation Crop Cultural Practices Conflicts / IssuesHigh Risk Disease Break Nutrition andIrrigationHygieneOtherIn an integratedweed managementprogram, it is importantto minimise thepopulations of weedssetting seed. It maymake economic senseto selectively handweedin the weeksbefore harvesting,particularly if weedseed development canbe prevented.Within one day of finalharvest all weeds andcrop residue should bedestroyed.Part of the post-harvest activities are to review the impacts of various control activities on the yield and “pack out” to improve and pest andweed control for subsequent seasons. A key part of the IPM process is to record percentage crop damage and “pack out” rate, crop residuemanagement, migration of beneficial insects and insect pests, rotation – length, break crops and follow on crops.Lettuce Best Practice 53

Farm Services Victoria 54ReferencesDiseaseBiological Controls for Sclerotinia Diseases, Villalta, Oscar, et al. (2004), Booklet,Information guide, Department of Primary Industries Vic. Available fromHorticulture Industry Network website Black root rot in lettuce, Martin, Heidi (2010), available from Queensland, DEEDIPrimary Industries website. Available from Queensland, DEEDI Primary Industrieswebsite Common Diseases of lettuce, James, Leigh & Tesoriero, Len, Department of PrimaryIndustries, Identification poster, NSW Primary Industries, Industry & Investment.Available from NSW Primary Industries, Industry & Investment Bookshop (shouldalso be available on the NSW I&I website )Control of Sclerotinia diseases, Villalta, Oscar & Pung, Hoong (2005),Fact sheet, Vegenotes, Department of Primary Industries Vic. Available fromVegetables Victoria website Development of Biological Controls for Sclerotinia Diseases of Horticultural Crops,Villalta, Oscar & Porter, Ian (2004), Department of Primary Industries, Victoria(DPI). Available from Vegetables Victoria website Managing Downy and Powdery Mildew, Anthracnose and White Blister: Efficacy andeconomic benefit of control options, Minchinton, Elizabeth (2010), Fact sheet,Department of Primary Industries Vic. Available from Vegetables Victoria website, also available from HorticultureIndustry Network website Managing Soilborne Diseases in Vegetables: Rotation with green manure andbiofumigant crops shows disease control & yield benefits, Donald, Caroline(2010), Fact sheet, Department of Primary Industries Vic. Available fromVegetables Victoria website , also available from Horticulture Industry Networkwebsite Managing Sclerotinia Diseases in Vegetables: New management strategies forlettuce drop and white mould of beans, Villalta, Oscar (2010), Department ofPrimary Industries Vic. Fact sheet available from Vegetables Victoria website, also available fromHorticulture Industry Network website InsectA scoping study of IPM compatible options for the management of key vegetablesucking pests, Carey, David (2008), Queensland, DEEDI Primary Industries ProjectNumber: VG06094 available from AUSVEG website Common pests of lettuce, McDougall, Sandra & James, Leigh, NSW PrimaryIndustries, Industry & Investment, Identification poster. Available from NSWPrimary Industries, Industry & Investment Bookshop (should also be availableon NSW I&I website )Currant lettuce aphid, McDougall, Sandra & Creek, Andrew (2007), NSW PrimaryIndustries, Industry & Investment, PrimeFact 155. Available from NSW I&Iwebsite

Identification of Insects, Spiders and Mites in Vegetable Crops - WorkshopManual, 2nd Edition, Heisswolf, Sue, Kay, Iain & Walsh, Bronwyn available fromQueensland, DEEDI Primary Industries website (in press). Will also be availablefrom Queensland, DEEDI Primary Industries websiteIdentification of Insects, Spiders and Mites in Vegetable Crops – Trainer’shandbook, Heisswolf, Sue, Walsh, Bronwyn, & Bilston Lara available fromQueensland, DEEDI Primary Industries website (in press). Will also be availablefrom Queensland, DEEDI Primary Industries websiteIllustrated Key to the Aphids (Hemiptera: Aphididae) found on lettuce inAustralia, Fletcher, Murray (2005). Available from NSW DPI’s website Integrated Pest Management (IPM) of Lettuce Aphid in Tasmania, Hill, Lionel,Department of Primary Industries, Parks, Water and Environment, Tasmania(DPIPWE), Horne, Paul & Page, Jessica, IPM Technologies P/L and McDougall,Sandra (DPI NSW), Fact sheet. Available from Vegetables Victoria website Lettuce Aphid Threat, McDougall, Sandra; Westacott, Alan; Baker, Greg & DalSanto, Peter (2004), NSW Primary Industries, Industry & Investment. Fact sheet,Vegenotes. Available from Vegetables Victoria website Lettuce Integrated Pest Management (IPM), McDougall, Sandra (2003), NSWPrimary Industries, Industry & Investment. Fact sheet, Vegenotes. Available fromVegetables Victoria website Lettuce Leaf newsletters, NSW Primary Industries, Industry & Investment.Available from NSW I&I website Managing Western Flower Thrips & Tomato spotted wilt virus in Vegetables(2003), Department of Primary Industries Vic (CD – unavailable). Notes can bedownloaded from Horticulture Industry Network website andenter “WFT” into search.Silverleaf Whitefly Management, Subramaniam, Siva & De Barro, Paul (2006),Fact sheet, Vegenotes. Available from Vegetables Victoria website Western Flower Thrips, Burfield, Tony (2003), South Australian Research andDevelopment Institute. Fact sheet, Vegenotes. Available from Vegetables Victoriawebsite Western Flower Thrips Identification, Features to look for when identifyingWestern Flower Thrips, South Australian Research and Development Institute.Available from SARDI website Western flower thrips and tomato spotted wilt virus, McDougall, Sandra &Tesoriero, Len (2007), NSW Primary Industries, Industry & Investment, PrimeFact713. Available from NSW Primary I&I website, Western Flower thrips (WFT) insecticide resistance management plan, Herron,Grant; Steiner, Marilyn; Gollnow, Bettina & Goodwin, Stephen (2007) NSWPrimary Industries, Industry & Investment. Available from website, Which thrips is that?: A guide to the key species transmitting Tomato Spotted WiltVirus in NSW, Steiner, Marilyn, NSW Primary Industries, Industry & Investment,Fact sheet. Available from website, Lettuce Best Practice 55

Farm Services Victoria 56VirusAphid-transmitted viruses in vegetable crops: Integrated virus diseasemanagement, Persley, D. & Gambley, C. (2009), Queensland, DEEDI PrimaryIndustries, Fact sheet available from Horticulture Industry Network websiteThrips and tospovirus: a management guide, Persley, Denis; Sharman, Murray;Thomas, John; Kay, Iain; Heisswolf, Suzanne & McMichael, Lee (2008),Queensland, DEEDI Primary Industries. Available from website Viruses in vegetable crops in Australia: integrated virus disease management,Persley, D., & Gambley, C. (2009), Queensland, DEEDI Primary Industries. Factsheet. Available from Horticulture Industry Network website GeneralAgrilink information products.Many of the original Agrilink titles have now sold out. Contact the QueenslandGovernment Bookshop for availability, or thelettuce product can be downloaded from Diseases of Vegetable Crops in Australia, Persley, Denis; Cooke, Tony & House,Susan (2010). Available from CSIRO Publishing website Lettuce Information Kit – Update Reprint – information current in 1999,Battagila, Robert; Gilbert, Angelina; Henderson, Craig; Maltby, John; O’Brien,Rob; & Richardson, Brian (1999) Queensland, DEEDI Primary Industries.Available from website Guide to using native plants on the Northern Adelaide Plains to benefithorticulture (2009), Field guide, South Australian Research and DevelopmentInstitute. Copies may be downloaded from SARDI website Or through Glenys Wood,Tel: (08) 83039660Integrated Pest Management in Lettuce: Information Guide, McDougall, Sandra &Creek, Andrew (2002) NSW Primary Industries, Industry & Investment. Availablefrom NSW I&I Bookshop and available on website Lettuce: best production management practices (2003), Department of PrimaryIndustries, Vic. Available from Horticulture Industry Network websiteNative Vegetation and Pest Control (2008), Fact sheet, Vegenotes, Issue5. Available to download for registered users from the AusVeg website, or available fromVegetables Victoria website Pests, Beneficials, Diseases And Disorders In Lettuce: field identification guide,Goodwin, Stephen; Watson, Andrew; McDougall, Sandra & Creek, Andrew (2003),Field guide NSW Primary Industries, Industry & Investment. Available fromNSW I&I Bookshop and available on website ‘Revegetation by Design’ guidebook: A guide to using selected native plants toreduce pests and diseases in the horticulture region of the Northern AdelaidePlains, Taverner, Peter; Wood, Glenys; Jevremov, Dijana & Doyle, Bill (2006)South Australian Research and Development Institute. Available from SARDIwebsite

Scouting Protocol for Lettuce incorporating IPM (2005), Department of PrimaryIndustries, Vic. Available from Horticulture Industry Network websiteSlug control in vegetable crops, Bound, Sally (2005), DPIWE Tas, Fact sheet,Vegenotes. Available from Vegetables Victoria website Spray Sense: safe and effective use of farm chemicals, Hardy, Sandra & Scott,Mark (2006) NSW Primary Industries, Industry & Investment. Available fromNSW I&I Bookshop and available on website Vegetable Integrated Pest Management (IPM) in Tasmania: Manual, Wardlaw,Felicity (2004,) Folder, CD, DPIWE Tas. Available from DPIWE Tas websiteWeather for pesticide spraying, (2004) Pamphlet. Available from Bureau ofMeteorology website WeedsIntegrated weed management components for vegetables. Available fromQueensland, DEEDI Primary Industries website Weed Management, Frost, P. (2005), Fact sheet, Serv-Ag Research Pty Ltd,Vegenotes. Available from Vegetables Victoria website < http://vgavic.org.au/communication/vege_notes/weed_control.htm>Weed management in lettuce crops, Henderson, Craig (2008), Queensland, DEEDIPrimary Industries. Available from website Lettuce Best Practice 57

www.dpi.vic.gov.auGG/UG-L/1210