N.C. Flower Growers Page 2

Foundation Board meeting, and Darlyne and Ihad also been invited to the Golden Anniversaryof the Fred C. Gloeckner Company. Boardmembers had taken time out for lunch and Fred

and I were behind the others, walking up theavenue to the restaurant. Fred then told me about

New York City, its politics, problems, and joys,and I could not have had it better if I had jumpedon the best tour bus in town. The bulb fields and

redwoods had been replaced by thousands ofcars and people and noise, but Fred was equallyat home in both environments.

Fred Gloeckner has had a positiveinfluence on just about everything that hashappened in floriculture in over 50 years. Thirtyyears ago he wanted to give his thanks to thefloriculture industry in some way and he did it byestablishing the Fred C. Gloeckner Foundation.I wish I could tell you the number of graduatestudents who were able to continue their

educations and do their theses problems becauseof their assistantships sponsored by theFoundation grants. I wish I could tell you howmany cultural practices followed today got their

start with grant money provided by theFoundation. At the July Board meetingwe decided to obtain that information

but the search has not yet been completed.I wish we had completed the task beforehe passed away, so we could have toldhim how much his generosity hadaccomplished. We would have had tomake the report brief, however, becauseFred's modesty would have stopped usfrom dwelling on the subject.

I wish we could turn back the

years and honor Fred at our short coursenext month. Since that is not possible,maybe we can just take a moment andsay, "Thanks Fred."

Fred C. Gloecknerin Smith River, California, October, 1968.

CULTURAL PRACTICES AND IPM FOR POINSETTIAS

Douglas A. Bailey

An Introduction to IPM

Growers are becoming more aware ofintegrated pest management (IPM) each day,and the use of IPM is increasing throughout thecountry. Very simply, IPM is a way ofoptimizingpest control in an economically and ecologicallysound manner. As a management system, it hasfour main goals:

Protect the Quality of the Crop. Thefirst goal of IPM is to allow producers to growpremium plants without sacrificing crop quality.One preconceived notion that is a misconceptionabout IPM is that crop quality will suffer, thatplants will attain pest damage. This is simply nottrue.

Safeguard the Environment and theHealth ofGreenhouseWorkersand thePublic.

Environmental stewardship is everyone'sresponsibility and is a major focus of any IPMprogram.

Reduce Pest Management Costs.Pesticides are increasing in cost and growerscannot afford to waste chemicals either from an

environmental standpoint or an economic one.Through a continuous, integrated program, pestmanagement can be more efficientlyimplemented.

Use Pesticides Effectively. IPM is oftenperceived erroneously as advocating theelimination of pesticides; this is very far fromthe intent of the program. Chemical control isusually an essential partofan IPM program. Theintent is to make surepesticides are usedproperlyand as effectively as possible.

Why IPM?

As evident in the latest issue (August1990) of GrowerTalks, IPM has been gainingmore interest and recognition over the past fewyears. There are three reasons for this trend:

Lawsand Regulations. New legislationis restricting pesticide application, forcingcompanies to show a needfor apesticideprior tolabel approval. This trend will continue, andwith increased costs of developing newchemicals, growers must rely on chemicals to alesser degree in the future.

Pesticide Phobia. Media coverage hasbombarded the public with negative, exaggeratedand sometimes misleading information. Thepublic has responded with the predictableresponse of demanding a reduction in pesticideusage.

SingleStrategy Approach. SinceWorldWarII, pesticideuse has increaseddramatically,and many growers have relied almost solely onchemical control methods. Concomitantly,research in the private sector has concentratedaround the development of a better pesticiderather than an overall control strategy. This hasnot only left a technologicalvoid withrespect to

N.C. Flower Growers Page 3

alternatives to chemicals, it has led to pestresistance to pesticides leaving us with fewerdefenses againstdevastatinginsectsand diseases.

Integrated pest management willcontinue to be refined and implemented at anincreasing rate. Prior to effective use of IPMtools, growers should be aware of the basicprinciples behind IPM.

Basic Principles of IPM

When initiating a control program, it isessential toestablish procedures for determiningwhen control is needed. Once the problem hasbeen determined or anticipated, then strategiescan beplannedthat integratechemical, biological,cultural, and mechanical techniques for controlor prevention of pest problems. There are fourbasic principles of an IPM program:

Crop Monitoring or Pest Scouting. Beaware of the status of the crop as well as the peststatus;insectpopulationsand incidenceofdiseasecounts are important to determining populationtrends and in planning control strategies.Effective monitoring can also indicate whenpests are not present, preventing unnecessaryapplications of pesticide.

Proper Pest Identification. Know whatthe problem is prior to trying to control it. Mostpesticides are species specific and correctidentification is important for efficient control.

Correct Timing. Pesticide applicationsmade at the wrong stage ofa pest's developmentor when pests are not even present is a waste oftimeandmoney.Timingofchemicalapplicationsis crucial in an IPM program.

Precise Records. Crop records form thebasis for future pest management. With accuraterecords, pest control should becomeeasier withevery crop. Documentation of plant culturalpractices, environmental conditions as well aspesticideapplicationsshouldbemadefor futurereference.

Growers using IPM can make moreefficient and economical use of pesticides than

N.C. Flower Growers Page 4

growers relying solely on chemical controls.They are practicing environmental stewardshipwhileeffectively protecting the value and qualityof their crop.

Cultural Practices and IPM

Pathologists use an excellent diagram toexplain the interrelationship of the host plant,the pathogen or infecting organism, and theenvironment surrounding both when describingplant diseases. This "disease triangle" can bebroadened conceptually to encompass all plantpest problems (Figure 1). In an integrated pest

PLANT

PEST

Figure 1. Thepest triangle.ENVIRONMENT

management program, growers move beyondconfronting pest problems with only pesticides(Figure 2) and address the plant andenvironmental aspects of control (Figures 3-5).

PLANT

PEST "C^ ENVIRONMENT

Figure 2. The single strategy approach.

Pest approaches (Figure 3) do includepesticides, but also include pest monitoring, useof predators and pest parasites, and antagonisticmicrobes that may compete with/help exclude

PEST

PLANT

A

PEST TZS ENVIRONMENT

Figure 3. Pest approaches to IPM.

pest organisms. The importance of monitoringhas already been addressed. Predatorand parasitealternatives for use on poinsettia pests wouldinclude Australian lady beetle for mealybugcontrol and Bacillus thuringiensis israelensisforfungusgnat control. Growth mediacompanieshave begun to incorporate beneficial microbesinto their substrates that are antagonistic todiseasepathogens. Feasible alternatives are availablethat warrant grower investigation prior to solereliance on chemical pesticides.

Plant approaches (Figure 4) are just asimportant as pest approaches. Poinsettiaresistance to diseases and insects exists to varyingdegrees among cultivars. For example, whiteflieshave been shown to have a preference amongcultivars. Growers should be able to document

PLANT

\ENVIRONMENT

Figure 4. Plant approaches to IPM.

cultivarpreferences ofpests through their records.This information can be used to isolate

particularly susceptible (highly preferred)cultivars from the rest of the crop for moreeffective control.

The concept of preventing plant stresscannot be over-emphasized. For example, saltdamage of roots offers an opening for root rotorganisms such as pythium. Spray damage fromincorrectpesticide application provides an entrypoint for botrytis. Every attempt should be madeto prevent nutrient, moisture (excess as well asdeficient), or any other type of stress duringpoinsettia production.

Environmental approaches (Figure 5)are perhaps the least emphasized or advertisedcontrol methods available. However, theireffectiveness can be equal to chemical controls.

\3fe*PLANT

PEST ENVIRONMENT

Figure 5. Environmental approaches to IPM.

Weed Control. Growers should have

zero tolerance for weeds inside a greenhouse.Weeds under benches serve as a breeding groundfor pests and a haven for pathogens. They canserve as a sanctuary when pesticides are appliedto crops; after the pesticide threat is gone, pestssimply return from unsprayed weeds to theiroriginal home on the crop. Empty houses can befumigated with a fumigant such as methylbromide for weed prevention. Empty housescan be shut down, allowing temperatures toelevate and desiccate weeds. Finally, herbicidecontrol is possible, if necessary. Only diquat(Ortho Diquat), glyphosate (Roundup) andoryzalin (Surflan) are registered for use ingreenhouses. Plants SHOULD NOT BEPRESENT in the greenhouse when herbicidesareapplied. Reintroduction of plantmaterial isnot advised for at least 24 hours after treatmentwith diquat orglyphosate, andonly after 14daysif oryzalin is used. Oryzalin WILL

N.C. Flower Growers Page 5

VOLATILIZE IF TEMPERATURES RISEABOVE 80°F; this is the reason for the 14 daywaiting period prior to moving in plant material.Do not use herbicides in a greenhouse withoutfirst consulting the North Carolina weedextension specialist for ornamentals.

Relative Humidity. Control of relativehumidity in a greenhouse can be a frustratingbattle. The physics of a greenhouse andphysiology of plant growth lead to increasedmoisture content in the air; evaporation of soilmoisture is trapped by the greenhouse glazingand plant transpiration increases ambient watervapor.

During most of the poinsettia season,relative humidity can be reduced if growers willvent each evening just after sunset, exchangingcooler outside air for air within the greenhouse.As thecooler air is warmed, therelative humidity(RH) will be decreased. For example, assume itis 40°F outside and rainy. There is 100% RHoutside of the greenhouse and the moisturecontent of the exterior air is 37 grains of water/lb of air. Inside, the temperature is 65°F and theRH is 90%; interior air moisture content is 83

grains ofwater/lb ofair. Theexample greenhousehas a volume of 39,348 ft3 (an 86' x 36' quonsethouse). For reduction of relative humidity,exhaust fans should be turned on long enough toexchange 1/2 of the air in the greenhouse (thetimerequiredtovent theneeded 19,674ft3 of aircan be calculated by knowing the CFM capacityof the exhaust fan). After exchanging 1/2 of theair,thegreenhouse is heatedto theset65°F. Theend result in the greenhouse is 65°F air thatcontains 60 grains of water/lb of air and has arelative humidity of 65%.

The cost of the air exchange can be easilycalculated. Given an acceptable margin of error,growers canassume thatoneBTU canraise -52ft3ofairl°F. In thegiven example, 19,674ft3 ofair must be raised 25°F. The total BTU outputrequired of the heating system to heat theairis:[19,674 ft3 •*• 52 ftVBTU/°F] x 25°F = 9459BTU's of heateroutput. The cost of 9459BTU

N.C. Flower Growers Page 6

output, assuming a 70% efficient natural gasheating system would be ~6#. If you exchangeairevery evening duringSeptember 1-December15, you have increasedyour heatingbill for theentiregreenhouseby only $6.36. The costofonefungicide application (material + labor +equipment depreciation) for botrytis control inthe same greenhouse would be greater than theincrease in the heating cost.

Temperature. Temperaturemanipulationforcontrol ofpests is more difficult thancontrolofrelative humidity. The greenhouse should bekeep close to temperatures optimum for plantproduction. However, growersshouldbe awareof temperature and how it affects pesticides andpests. Forexample, pesticide applicationsmadein the middle of the day when greenhousetemperatures arehighestcanleadtophytotoxicityanddamageplants. If greenhouses aremaintainedtoo cool, much below 60°F, the incidence ofPythiumand Thielaviopsis can increase. On theother hand, pathogens such asPhytophthoraandRhizoctonia prefer warmer temperatures andcan increase in importance if houses aremaintained too warm. Growers can reduce the

possibilityofbacterial softrotduring propagationby maintaining moderate temperatures;evaporative cooling can prevent excessivetemperatures that bacterial soft rot prefers.

AirCirculation. Adequate airmovementaround and within the plant canopy is necessaryto prevent condensation on foliage that couldleadto botrytis blight. Also, asplants transpire,theairimmediately surrounding leavesbecomessaturated with water vapor and RH approaches100%, increasing the chances of botrytisinfection. Proper air circulation can increasefoliar transpiration andincrease evaporation ofsoil moisture from the soil surface, thusremovingexcess soil moisture. Unfortunately, all theadditional watervaporincreases theambientRHof the greenhouse, so air exchanges becomeeven more important.

Spacing. Crowdingplantsresultsinleggygrowth and stretching of shoots. Inadequatespacingalsoreduces aircirculation, canincreasedisease potential, and decreases pesticidecoverage. Itisrecognized thata 15" x 15" isnotaseconomical as 12" x 12"ifthe onlyeconomicfactor considered is $/ft2, but crop quality andcost of pestcontrolsmust alsobe considered aseconomic factors when deciding on spacing.

In summary, effective and efficient pestmanagement addresses pest control from thepest,plant, andenvironmentalanglesin ordertointegrate control techniques into a economicalprogram that protects crop quality and theenvironment.

POINSETTIA DISEASES AND THEIR MANAGEMENT

Ronald K. Jones, Extension Plant Pathologist

Diseases and their management must bean integral part of a poinsettia productionprogram. Diseases are a threat to a poinsettiacrop from the establishment of stock to sale offinished plants. The management of the manydiseases thatoccuronpoinsettia(Table 1) requirea totally integrated program that includessanitation, cultural practices, environmental

control and as a last resort, the proper use ofpesticides.

DescriptionofMajorPoinsettiaDiseases.The importance and control of each of thefollowing diseases will be discussed for eachphase of production: stock plants, propagationand finishing.