PAT 1-19

Pesticide Applicator Training Manual

Interior Plantscape Pest ControlCategory 19

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INTERIOR PLANTSCAPE PEST CONTROL

Living plants are commonly used indoors, primarily foraesthetic purposes. Restaurants, shopping malls, and officebuildings use plants to make the indoor environment morepleasing for customers and employees. To maintain healthyinterior plants you must have an understanding of theoptimal growing conditions for the species of plantsinvolved. These include proper light, temperature,humidity, soil moisture and pH. Providing these conditionsbecomes challenging when an interior landscape cancontain 20 or more species of plants in a variety ofenvironments.

Indoor plants are susceptible to attack by many kinds ofpests. In addition, the plants often are under great stress dueto less than optimal growing conditions. Some plants maybe struggling to stay alive and are growing slowly, if at all.These plants may be mistreated, too, such as having coffee,soda pop, or cleaning liquids poured on them. Under thesestressful conditions plants are more susceptible to pests andless capable of recovering from an attack.

Treatment options in the interior plantscape are limited andindoor pest control is a highly sensitive issue. Controlmeasures must be safe for humans and for the plantsthemselves. Pest control can be made safer by selectingpesticides carefully, limiting applications, using lowestpractical rates and correcting improper cultural practicesthat contribute to the problem. Using all available tactics orstrategies to manage pests so that an acceptable appearanceand quality can be achieved economically and with the leastdisruption to the environment is called integrated pestmanagement (IPM.)

The goal of IPM is to reduce the occurrence of plantproblems and maintain insect populations and diseaseproblems at levels where aesthetic and economic losses aretolerable. Rarely is pest eradication a goal nor is it possible.All economically and environmentally sound practices thathelp prevent or reduce plant injury are used. Integrated pestmanagement incorporates a wide range of pest controls suchas resistant plant varieties, cultural practices, mechanicalcontrols, biological controls and pesticides.

The basic components of an IPM program include:

• Regular monitoring and early detection of disorders. • Proper diagnosis and identification of plant disorders.• Determination of economic significance. • Selection of management methods. • Evaluation of management methods

MONITORING AND DETECTION

Typically, a plantscape manager visits an interior landscapeon a regularly scheduled basis. Monitoring for plant pests orpoor growing conditions should be an integral part of eachvisit. While watering, rotating, and cleaning, be alert togeneral plant health and watch for signs or symptoms ofpest infestations. Early detection allows you to managepests or alter conditions before host plants suffer seriousinjury. In addition, low levels of pest infestation aretypically easier to manage and the use of less toxicmanagement strategies will still be an option. Washing thefoliage with a 2 percent soap solution, pruning the problemout, or correcting a poor site condition may eliminate theproblem without the use of a pesticide.

Some insect species can be detected with the use of yellowor blue sticky cards. These cards, approximately 3-inches by3-inches, have a sticky substance on the surface. Insects thatcome in contact with the card's sticky surface cannot escape.The cards are either hung in the canopy of the plant orattached to a stick inserted in the soil. Yellow cards arehighly attractive to whiteflies and thrips, while blue cardsare more specific for thrips. Both colors also will attractfungus gnats. Observation of these cards will help todetermine what insects are present and show relativechanges in numbers from one visit to the next. It isimportant to write down the numbers and types of insectsper card on each visit. Change the cards on a regular basisor when they become so heavily covered with insects that itis too difficult to count them, or after a pesticide treatment.

To keep monitoring and detection information uniform,develop a system to rank plant condition. If time allows,documenting healthy plant conditions provides a writtenrecord of your inspection. If a problem does occur, thisbackground information will help in making a diagnosis.Record information useful for planning managementstrategies:

• Level of light (footcandles)• Plant species • Plant age and size• Date of installation • Size of container • Type of soil media • Life stage of the pest • Type and level of damage • Date of detection, etc.

DIAGNOSIS AND IDENTIFICATION

When damage or poor plant health is detected, the interiorplantscape manager needs to determine what cultural orenvironmental conditions, diseases, insects, mites, or humanactivity is responsible. Remember, there is often more than

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one damaging influence. Identify all conditions that mayhave stressed the plant, causing it to be more susceptible tothe problem or pest observed. Below is a general guide tocommon symptoms and possible causes of indoor plantdisorders.

Identify the plantCertain plant species are moreprone to specific pest problem.Ficus are susceptible to scales,Schefflera are susceptible tomea l y b u g s , p a l ms a r esusceptible to spider mites, ferns areprone to bacterial leaf spots, andDracaena are prone to root and stemrots.. Inspect the whole plant, especially the underside-stems, and twigs. If possible, carefully remove the plantfrom its container to examine root and soil conditions.Inspecting the root environment is often difficult butnecessary.

Clearly define the symptoms Where do the symptoms occur on the plant? Are they atrandom locations, localized, or in a pattern? Are thesymptoms that you identify the same as the symptoms yourclient is concerned about?

Categorize the cause of the problem as contagious ornoncontagious

Contagious disorders may be caused by insect or miteinfestations or disease

Noncontagious disorders may be caused byproblems with light, temperature, humidity,water, media, pH, soluble salts, volatile

gas, cleaning compounds, relocating,breakage, food/beverage wastes,

watering with excessively coldwater

Although fungal, bacterial, andviral infections can be common inproduction environments, the

interior plantscape environment isgenerally not favorable for disease

organisms when appropriate cultural andenvironmental conditions provide for stress-free plants.Keeping foliage dry and relative humidity low, commonconditions in indoor landscapes, is perhaps the best controlfor foliar diseases. Root rots can be a problem for indoorplants but generally only when the roots are first damagedby over- or underwatering or high levels of soluble salts inthe soil. Therefore, if a root problem occurs, evaluatewatering and fertilizing practices and the drainage of thesoil and container.

Consider these factors of the macroclimate: Where are theheat or air-conditioning vents? Are there drafts fromdoorways? Are light levels adequate? Note temperature andhumidity levels and the plant's proximity to windows. Askthe client about activities that may disturb the plant. Is thecontainer being used as a receptacle for coffee, cigarettebutts, or cleaning compounds?

SELECTION OF PESTMANAGEMENT METHODS

The pest management methods most appropriate for aspecific circumstance will depend upon the biology of thepest and host plant, and the interior landscape situation. Forevery pest problem consider all available managementtactics and evaluate the benefits and risks of each.

Choose methods that are:

• Practical in an indoor setting. • Least toxic to nontarget organisms. • Enhance natural controls and plant defenses. • Likely to limit the pest permanently. • Least hazardous for the applicator to handle.

Also, as a plant manager, consider the option of removingthe plants to be treated from an interior landscape andtemporarily relocating them outside or to a greenhouse.Relocating plants makes available a larger selection ofproducts registered for use in those areas (including somethat may have been canceled for use in the interiorlandscape setting.) Furthermore, the conditions in agreenhouse (light, temperature, and water) may be moreconducive to the plant's recovery. Once the plant has beentreated and the problem corrected, it can be replaced in itsoriginal interior landscape location.

IPM EVALUATION

It is extremely important to evaluate the results of your pestmanagement strategies. This can be done in several ways.Record pest counts or level of infection before and aftertreatment, comparative damage ratings, length of recoverytime, etc. Sticky cards, as discussed under monitoring in thissection, are helpful in evaluating the results of an insectmanagement treatment. Keep written records of successesand failures, timing of treatment, and special conditions.

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A General Diagnostic Guide for Indoor Plantswith Symptoms and Possible Causes

Brown or scorched leaf tips1) Poor root health from overwatering, excessive soil

dryness (especially between waterings), excessivefertilizer or other soluble salts in the soil or root rotdisease.

2) Specific nutrient toxicities such as fluoride, copper orboron.

3) Low humidity. 4) Pesticide or mechanical injury.

Leaf spots, blotches, blemishes, blisters, or scabby spots1) Intense light (sunburn) associated with a recent move

of the plant or excessive soil dryness and wilting. 2) Chilling injury (below 50° F). 3) Chemical spray injury. 4) Overwatering. 5) Fungal or bacterial infections (not common unless

plants have recently come from a field or greenhouse).

Older leaves yellow-green1) Insufficient fertilizer, especially nitrogen. 2) Poor root health due to pot-bound growth, compacted

soil, or poor drainage. 3) Insufficient light. 4) Senescence (natural aging process, individual leaves).

Newer leaves yellow-green1) Soil pH (acidity) imbalance. 2) Trace element imbalance.

All leaves yellow-green1) Too much light. 2) Insufficient fertilization. 3) High temperatures, especially when associated with

dryness. 4) Insect infestation or root rot disease.

Leaf drop1) Poor root health from overwatering, excessive dryness

or excessive fertilizer or other soluble salts in the soil,compacted soil or pot- bound roots.

2) Sudden change in light, temperature, or relativehumidity.

3) Root rot disease.

Wilting or drooping of foliage1) Poor root health from overwatering, excessive dryness

or excessive fertilizer or other soluble salts in the soil,compacted soil, or a poorly drained container or rootrot disease.

2) A toxic chemical poured into the soil.

Roots brown in color, soft or rotted roots with tissuethat can easily be "slipped off" leaving behind thestring-like center tissues; roots massed at top or bottomof pot.

1) Poor root health from overwatering, excessivedryness, excessive fertilizer or other soluble salts inthe soil, compacted soil, or a poorly drained container.

2) A toxic chemical poured into soil. 3) Over or underwatering. 4) Root rot disease.

Yellowed leaves with tiny speckling; leaves later bronzedand drying; webbing noted neargrowing points.

1) Spider-mite infestation. Leaves or stems covered with a sticky substance; moldgrowing on leaves; tiny brown or white objects seen onleaves or in crotches of branches; leaf drop or branchdieback; leaf or growing point distortion.

1) Scale, aphid, or mealybug infestation.

Material adapted from Michigan State University ExtensionBulletin E-2308 Interiorscape Pest Management. ATraining Manual for Commercial Pesticide Applicators.Julie Stachecki, Editor.

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CHAPTER TWO

PLANT SELECTION AND MANAGEMENT

PLANT SELECTION - The most important step ininteriorscaping is the selection ofplants matched correctly with the

environmental characteristics of theplanting site. Plants differ significantly intheir light needs, sensitivity to temperature,

and ease of maintenance. This, in turn,impacts their susceptibility to pest

problems.

Consistent success with indoor plants is most likely to beachieved by:

• Selecting plants that match the conditions of a giveninterior environment.

• Purchasing high quality plants from a known andreliable source.

• Acclimating the plant before installation by reducinglight, moisture, and fertilizer.

• Watering, fertilizing, cleaning, and pruningappropriately.

Light is probably the most important environmentalcondition and plants should be placed andgrouped according to their need for light.Plants grown under correct lightconditions are vigorous, compact, andbushy. Color is vibrant, leaves arenormal in size, stems are sturdy, andflowering is promoted.

Light helps balance food production( p h o tosyn thes i s ) a n d f o o dconsumption (respiration) bythe plant. The rate at whichplants make their own food isdetermined essentially by thequantity and duration of available light. The higher the lightlevel, the greater the supply of food. The rate of foodconsumption is basically determined by temperature. Thewarmer the temperature, the greater the demand for food.Therefore, in interiorscapes, the low light and warmtemperatures create a high demand for food but a slow rateof production.

Plants grown at a light intensity below their optimum willhave smaller leaves and less vivid color. They often growmore open and leggy, and pruning may be necessary forcompact form. They need to be kept drier than those inbright light and fertilized less frequently. A plant thatreceives significantly less than its required amount of lightmay survive for several months to a year, while graduallydeteriorating in appearance and vigor.

Three factors lower the light requirement for a plant movedindoors. First, the plant's growth slows dramatically or evenstops. This growth reduction triggers a lesser demand forfood. Second, while the existing leaves cannot change theirstructure, they can increase their chlorophyll content. Third,the new leaves that are produced in the indoor environmentwill be structured as shade leaves. This has been shown toresult in a reduction in the plant's light compensation point.

The light compensation point is defined as the minimumlight level at which the amount of food produced byphotosynthesis is equal to the amount of food consumedduring respiration. Shade leaves have lower lightcompensation points than sun leaves. Acclimation to lowlight involves a reduction in the plant's light compensationpoint either by changes in leaf metabolism so light energyis captured more efficiently in low light or by replacementof inefficient sun leaves with shade leaves tolerant to lowlight levels.

Artificial light can be used to supplement or replace naturalsunlight. Cool-white fluorescent lights used alone or incombination with warm-light fluorescent lights are the mosteconomical and best all-purpose lamps. Typically, a fixtureholding two 40-watt tubes is positioned approximately 12inches above the plants. Most plants need 12 to 16 hours ofartificial light per day for good growth. For large specimenplants, use spot or flood lights to maintain good appearanceand accent the plant. Lighting design should take intoaccount anticipated use of indoor plants. Indirect and tracklighting are very effective design features for this purpose.

Understanding how a plant reacts to temperature stress isimportant in making adjustments to correct problems andimprove plant longevity. In addition to problems caused bychilling, heat from registers can dry outmedia and foliage quickly. A minimum/maximum thermometer will recordtemperature differences plants may beexperiencing in the interior landscape.

Most public buildings are heated and cooledwith human comfort in mind rather than thegrowth requirements of indoor plants.Fortunately, the desirable temperatures for humans fallwithin the optimum range for most foliage and floweringplants. Daytime temperatures of 70 to 80°F and a nighttimerange of 60 to 70°F are satisfactory for most species. Manyflowering plants bloom longer at the lower end of theseday-night temperature ranges. Variations in temperatureranges should be considered in selecting plants for theinterior environment.

Plants differ in their degree of sensitivity to chilling.Generally, most foliage plants cease to grow at 60°F.Temperatures between 45 and 55° F often result in chilling.Chilling causes changes in cell membrane structure, which,

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in essence, causes the cells to "leak" their contents. Thiscauses a loss in plant vigor and reduced growth. Thedamage may not be visible for months after chilling hastaken place. Many times a secondary problem such asdisease will begin to increase due to the loss of vigor. Thissecondary problem is then blamed for the damage, andchilling goes undetected.

Chilling damage is very subtle and may be very difficult todetect unless maintenance personnel are looking for it.Symptoms of chilling injury include:

• Foliage discoloration. • Poor growth or wilting. • Foliage bending or curling. • Flower bud drop. • Plant death.

The severity of chilling damage is a result of temperatureand length of exposure. For example, exposure to 50°F for12 hours may cause chilling injury as severe as exposure to40°F for 2 hours. Chilling injury can result from only a fewminutes exposure at freezing temperatures. Plants can getchilled in the truck going to a job site, during transfer fromthe truck to the indoors, and from exposure to cold windsnear doorways. The following conditions can contribute tochilling injury in the interior environment:

• Shopping malls and public buildings that maintainlower temperatures.

• Air drafts from air conditioning units, doorways, andwindows can cause sudden changes in temperature.

• A reduction of temperature in public buildings onweekends and holidays.

MAINTENANCE IN THE INTERIORSCAPE

Once plants have been properly placed, their appearanceneeds to be sustained through proper maintenance and care.Usually, this is limited to watering, fertilizing, cleaning, andpruning.

Watering indoor plants is a widely misunderstood practice.Water content in the container and plant need for water aredifficult to measure accurately. As a result, improperwatering is the underlying cause of many plant problems.

Fertilization is necessary forgrowth and maintenance of plants.A plant's need for fertilizerdepends on its growth rate, theamount of leaching that occursduring watering, soil volume, andother factors. Fertilizer levels that

were ideal during production can severely damage plants ininteriorscapes. Soluble salts in the media can cause root

burn when too much fertilizer is applied, when the mediumdries out, and when water quality is poor.

Plant cleaning includes dust andwater-spot removal, leaf shining, andremoval of senescent leaves. Theleaves of indoor plants canbecome coated with a heavylayer of dust in a surprisinglyshort time. This dust andgrime interferes with normal leaf functionsand makes the plant less attractive. Accumulated dust willshade the leaves and may so drastically reduce light that theplant will eventually die. Dust with a soft brush or clothmoistened with warm water to clean both upper and lowerleaf surfaces at least every two or three months.

Pruning to encourage branching or to remove an entiresection of the plant to maintain its intended design or sizemay be necessary. Pruning may be used to remove insectpests, such as scales, that may accumulate on specificbranches.

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HAPTER THREE

DISEASES OF INDOOR PLANTS

The occurrence of diseases on indoor landscape plants istypically a result of adverse environmental conditions or thepresence of infectious agents. Diseases solely caused bymicroorganisms (fungi, bacteria, viruses or nematodes) arenot common in the indoor landscape setting if the landscapewas established using disease-free plant material andconditions conducive to disease development are avoided.It is critical to identify the causal agent or the type ofdisease that arises in the interior landscape in order to takeappropriate corrective measures. Plants are subject to twotypes of disorders:

Abiotic or non-infectious disorders; caused byenvironmental, cultural, and non-living things. Thingscausing abiotic or non-infectious diseases do not grow,reproduce, or spread from plant to plant; they are notcontagious.

Biotic, infectious or pathogenic diseases; caused by livingpathogenic microorganisms such as fungi, bacteria, viruses,or nematodes. These microorganisms can spread from plantto plant.

To manage plant diseases and disorders successfully, plantmaintenance technicians must be able to:

• Recognize symptoms and signs that indicate thepresence of a disease or disorder.

• Accurately identify the cause and type of problem(abiotic or pathogenic or both).

Select the best method(s) for correcting conditions thatcontributed to the disease development.

ABIOTIC DISORDERS

Abiotic disorders produce a wide range of symptoms suchas reduced vigor, yellowing leaves, leaf drop, or rapid deathof plants. The abiotic conditions causing severe damage areeasiest to recognize and correct. Less obvious symptomsmay go unnoticed and therefore the unfavorable conditionor cultural practices may persist for a long period of time.During this time plants are stressed and become moresusceptible to pathogenic diseases. For example, if powderymildew develops on a plant that is usually resistant to thisdisease, an investigation may reveal that the plant wasconsistently overwatered, resulting in high moisture andhumidity (abiotic conditions) in the planting area. In thiscase, correcting the cultural practice that allowed thepathogen to become established may be the only correctivemeasure necessary for managing the powdery mildew.

Many cultural and environmental conditions that lead topoor plant health are mentioned throughout this manual.

This section will focus on some of the most likely abioticdisorders found in an interior landscape.

Environmental Conditions Contributing to AboticDisorders

There are certain ranges of temperature, light and humiditythat provide for optimal plant health. The importance ofthese factors is considered here in relation to thedevelopment of abiotic disorders.

Typically interior spaces utilized for living or workenvironments provide temperatures adequate for growingfoliage plants. A temperature range between 50 and 90°Fahrenheit can be tolerated by most foliage plants. Attentionmust be given to temperatures during times when interiorspaces are not occupied by people. With a moreenergy-conscious society, the thermostat may be set totemperatures that may injure plants when they are exposedover a period of time. Foliage plants can suffer cold damagewithout freezing. This is referred to as chilling injury. A fewplants that are injured by exposure to chilling temperaturesbetween 35 and 50° F for short periods of time includeAglaonema X 'Silver Queen', Dieffenbachia maculata,Dracaena spp. and Polyscias fruiticosa. Symptoms ofchilling injury include yellowing or brown water-soakedareas on leaves, loss of foliage, poor growth, and wilting.

Plants exposed to hot temperatures for prolonged periods oftime can also suffer injury. Wilting, marginal burn onfoliage, and leaf drop may occur. Since most foliage plantscan tolerate temperatures as high as 95°F, provided theyreceive adequate water, the problem is not related entirelyto maximum temperature but to utilization of stored foodreserves due to elevated respiration levels. When a plantdepletes its stored carbohydrates, it may become weak andpredisposed to other stresses including invasion bypathogens.

Light affects numerous physiological conditions andprocesses in plants. When plants are subjected to inadequatelight levels, disruptions of these functions may cause stress.Plants may exhibit poor growth and color. These symptomsare easily mistaken for something other than poorenvironmental conditions.

If plants haven't been adequately acclimatized to theconditions of an interiorscape (lower light levels, lowertemperatures and humidity), they may experience yellowingand leaf drop and possible death following installation.

Many growers are producing acclimatized plants whichrequire more time to grow, but are more tolerant ofenvironmental stress at the job site. Be familiar with thegrowing practices of your supplier and symptoms associatedwith an inadequately acclimatized plant. If the growerdoesn't acclimatize the plants, establish a method and

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facility to do so before installing the plants directly into aninterior landscape.

Cultural Practices Contributing to Plant Disorders

Most plant replacements result from a combination of poorenvironmental conditions and poor cultural practices.Abiotic disorders symptoms, resulting from poorenvironmental conditions and cultural practices, areextremely variable and are often misdiagnosed. Pesticideapplications will not correct an abiotic disorder. It is vitalthat plant technicians understand the impact of their culturalpractices on the plants they maintain.

BIOTIC DISORDERS

It is helpful to understand which conditions influence bioticdisease (also known as infectious disease) developmentwhen managing the health of plants. The disease triangleillustrates the primary factors that must be present andfavorable for a biotic disease to occur. These are:

Pathogen: the abundance, aggressiveness, and othercharacteristics of the agent causing the disease influence thedisease development. Some pathogens are widespread andattack many plants; others are not.

Host Plant: the genetic susceptibility and general conditionof the plant influence disease development. Healthy,stress-free plants are less susceptible to pathogens thanweakened plants. Different species or cultivars of plantsmay be more or less susceptible to attack.

Environment: certain environmental conditions favor theinfection of the plant by a pathogen. These includetemperature, moisture, humidity , soil conditions, light,density of the planting, and location of the plant.

Time is another factor that influences disease development.Time and the three components of the disease triangle allinteract with one another. While one factor may be mostimportant in a particular disease and less important inanother, no single factor acts alone.

The goal of a plant pest manager is to recognize andmanipulate these primary factors to promote stress-freeplants and eliminate conditions favorable to diseasedevelopment. Remember, problems on plants generally donot arise from one isolated cause.

Infectious Diseases

The disease triangle reminds us of the factors necessary fora pathogen to infect a plant. A susceptible host plant and apathogen must be present along with the properenvironmental conditions in order for a disease to occur.Conditions that favor the development of pathogenic

diseases can be avoided in the interior landscape setting.Overhead irrigation, splashing water, prolonged leafwetness, high humidity, crowded blocks of similar plants,and propagation of infected stock are conditions more likelyto occur in a greenhouse production setting.

Typically, diseases in the interior landscape result as asecondary infection after a plant has been stressed byadverse cultural or environmental conditions. Correcting thestress often prevents the development of diseases.

When a disease appears in the interior landscape, it ispossible that it is a continuation of a situation that began inthe greenhouse. The goal of plant growers is to producehigh-quality plants as free of pests as possible. Greenhousegrowers commonly use pesticides to suppress thedevelopment of diseases. The suppressed diseases maybecome prominent in an interiorscape where fungicideapplications are not routine.

The use of fungicides is not always possible in an interiorlandscape setting due to the need for repeated treatmentsand the limited number of fungicides registered for use ininterior landscapes. The only fungicides currently labeledfor use in the interior landscape are those that are applied tothe soil, typically as a soil drench. If a fungicide is labeledfor use on the plant(s) and for the pathogen you need totreat, but is not labeled for use in an interior landscapesetting, you may temporarily relocate the plant to a locationthat is on the label (such as outdoors or in a greenhouse)and then make the treatment. By removing a plant from itsinterior landscape, the options for fungicide applications areexpanded, although temporarily relocating plants may notalways be practical. Prevention is the most practical andeffective way to manage disease.

Most pathogenic diseases of foliage plants are caused byfungi, bacteria and viruses. Observing symptoms and signsprovides clues to the type of pathogen causing a disease butmay not indicate the specific agent. Accurately diagnosingthe specific pathogen causing the problem is critical forselecting appropriate corrective measures.

Any fungicide will only be effective in controlling thosespecific pathogens listed on its label. Knowing the exactpathogen causing your problem is important. Accuratediagnosis of plant pathogens may require laboratoryanalysis. A fresh, representative sample produces the mostaccurate diagnosis. It is best to collect and submit samplesearly in the week so that the sample does not arrive duringa weekend or holiday when there will be time for it todeteriorate. Large samples will generally enable a quick,correct diagnoses. Send a whole plant if feasible. Otherwise,collect leaves, stems, and roots from plants showing thesymptoms. Include the full range of symptoms. Rememberthat leaf symptoms may be the result of a stem or rootproblem. Also, include a small sample of soil from the

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roots. Diagnostic assistance can be obtained from your localCooperative Extension Service.

Disease symptoms on foliage or stems are the most likely tobe noticed. A quick response can stop the spread of apathogen on the host and to other plants. If plant damage isnot severe and has been checked by your managementprocedure the plant may still be attractive enough to remainon site. Root diseases are less likely to be noticed untildamage is severe. When an infection becomes severe, thebest alternative is removal of the plant and infested growingmedia.

Fungi Fungi are the most prevalent plant pathogen of indoorornamental plants. They cause a number of leaf spot, stem,and root rot diseases. Most foliage diseases caused by fungidevelop circular, dead spots or lesions on leaves, stems andflowers. The gray-to- brown center is dry and papery, witha darker edge. As surrounding tissue is invaded, lesions mayexhibit concentric rings which gives the affected tissue a"target-like" appearance with a faded green halo formingthe outermost ring. These circular lesions can overlap,forming larger lesions, producing a blotchy appearance.Also, look for black, pinpoint-like pustules within thelesion. These black specks are the reproductive structures ofthe fungus which develop on or in diseased tissue. (Not allfungi produce these structures.) Inside these structures aremillions of spores that are easily carried by air currents,water or soil movement, and human activity. After reachinga host plant, spores can remain inactive for long periodsuntil conditions are favorable for growth and infection ofplants. Temperatures from 60 to 80°F and high moisturelevels encourage fungus growth.

Bacteria Although plant diseases caused by bacteria are less commonthan fungal diseases, bacterial pathogens can cause some ofthe most economically damaging diseases. There are nochemical controls available for managing bacterialinfections in indoor landscapes. Prevention is directed atreducing the number of bacterial sources and avoidingconditions that are favorable for growth of bacteria. Culturalcontrol and sanitation are important aspects of prevention.

Moist conditions and high humidity from splashing ormisting contribute to the spread of bacterial disease.Bacteria are single-celled, microscopic organisms. There aretwo types of bacterial plant diseases:

• Systemic infections which occur in the plant's vasculartissues (water- and nutrient-conducting tissue), and

• Localized infections which appear as leaf and/or stemlesions.

Systemic infections are limited to the vascular tissues ofstems, crowns, and sometimes roots. They cause wilting and

general yellowing of plants. Occasionally systemic bacterialdiseases may cause rotting or cankering of the stem tissue.These cankers or rots will be soft and mushy in appearanceand may have an unpleasant odor. Early stages are almostimpossible to diagnose. Later stages are easier to diagnose,however, the disease is so extensive by this point thattreatment is impossible. If bacterial diseases are diagnosed,the best action to take is to remove the infected plant fromthe site and destroy it.

Localized bacterial disease symptoms can be in the form ofleaf spots and/or stem rots. Bacterial leaf spots may bedistinctly different from fungal leaf spots. They are darkgreen with a greasy, water-soaked appearance when viewedfrom the underside of the leaf. Eventually these areas turntan, dark brown, or black depending on the plant speciesand the bacterium involved. A distinct yellow band(referred to as a halo) often surrounds the periphery ofinfected tissues. The yellow region can also be described aschlorotic, meaning the tissue becomes yellow because thechlorophyll has been destroyed. A small slice of the lesionplaced in a drop of water may emit a stream of bacteria fromthe tissue. The water will appear cloudy. Early detectionwill allow you to prune out infected plant parts and possiblysave the aesthetic value of the plant. Clean hands with soapand water and disinfect pruning tools in 70 percent alcoholafter such removal actions.

The spots or lesions of localized infections can enlargerapidly and consume the entire leaf within a short time.Such fast-moving infections often spread into leaf petiolesand stems. Plant tissue becomes soft and mushy, often witha foul odor. In advanced stages, brown ooze is found inveins throughout the plant. Control of these diseasesgenerally involves prompt removal of infested plant parts.

Viruses Viruses are much smaller than bacteria. They enter the cellsof a plant and are multiplied by the host. Viruses live andmultiply only within living cells. Viral diseases are usuallyintroduced into interior landscapes by the use of infectedplants or by insects. They can be spread to healthy plants bythe feeding activity of sucking insects such as aphids andleafhoppers, or on the hands and tools of maintenanceworkers. Currently there is no chemical control for a virusonce it infects a plant. Although most viruses are specific toonly a few types of plants, prompt and complete removal toprevent its potential spread is recommended when a virus isdiscovered.

Symptoms of viral diseases are very diverse. Some viraldiseases have symptoms similar to fungal diseases.Symptoms of viral infection include:

• Mosaic patterns on leaves (a mixture of irregularlyshaped dark- and light-green areas on the leaf).

• Yellow streaking of leaves, especially monocots.

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• Yellow ringspots or lines on leaves. • Veins becoming distinctly yellow. • Uniform yellowing, bronzing or reddening of leaves. • Cup-shaped leaves. • Crinkling or curling of leaf margins. • Distortion of leaves and growing points.

• Stunting of growth.

Diagnosing a viral disease should not be based only onsymptoms. If you suspect a virus, isolate the diseased plantand obtain assistance from your local CooperativeExtension office.

Root Diseases

Root rots are the most common disease problem with indoorornamental plants. Most root rot diseases are caused byfungi.

Infectious root rots can be diagnosed to some extent bydirect observation of the root system. Healthy roots ofherbaceous plants should appear white and firm. Offcolor orbrownish- to-blackish, limp roots often indicate that root rotis present. Being able to pull off outer root tissue with yourfingers (leaving the string-like center of the root behind) isa good sign that root rot is present. In order to determine thehealth of a root system, you should know what a healthyroot system looks like. Conditions of the above-groundportions of the plant that indicate a root problem includesmaller and less vigorous growth, new leaves that may besmaller and fewer than normal, and old leaves that turnyellow and fall beginning at the base of the stem. Also, theplant may droop and new shoots may emerge from thelower stem.

Two of the most common root rot fungi involved in root rotdisease are the water molds, Pythium spp. and Phytophthoraspp. These organisms are called water molds because of aspore stage that is adapted to spread by swimming in water.These organisms, even if present, are not a problem unlessplants have been subjected to poor environmentalconditions or cultural practices. High moisture levels inpotting soil due to overwatering, poorly drained media, orwater standing in the bottom of the containers induceinfection of roots by these fungi. Root damage caused byoverfertilization, build up of salts in the soil, chilling orfreezing temperatures, or phytotoxicity caused by impropersoil drenches can also lead to root rots.

Drainage of the media and establishing proper irrigation,fertilization and good sanitation practices help avoid and/orcorrect root rot diseases in general. Be aware of the changesin the physical structure of the rooting media. As mediaages it may settle and pack in the bottom of containers andhinder drainage.

Rhizoctonia solani is a soil-borne organism which is

especially damaging to roots and lower stems. Under highhumidity and cool weather conditions this organism, as wellas the water molds, can cause serious aerial blights (diseasesof above-ground plant parts). Only occasionally is this aproblem for indoor plants. R. solani has a wide host rangeand needs only minimal environmental requirements fordisease development. Therefore, this organism poses aserious threat where poor horticultural practices exist orwhen this organism has contaminated the potting media.

Other pathogenic organisms which can be equallydetrimental under the right conditions are Fusarium spp.,Cylindrocladium spp., Sclerotinia spp., and Thielaviopsisbasicola. These organisms are soil borne and persist in soilor artificial media for quite a while. Therefore, the bestmanagement of these pathogens, as all the others, isprevention: Use only disease-free plants, avoid stressedplants or those with discolored roots or stems, monitorwatering practices closely, and practice good sanitationmeasures.

Nematodes Several types of tiny roundworms cause plant diseases onplants used indoors. Lesion nematodes (Pratylenchus spp.)and spiral nematodes (Helicotylenchus spp.) cause plantstunting and poor growth because their feeding weakens theroot system. The root knot nematode (Meloidogyne spp.)causes nodules to form on roots, thus impairing rootfunction. This causes stunting. The foliar or spring-crimpnematode (Aphelenchoides spp.) lives within the leaf tissuesof many indoor plants. It causes death of the leaf tissue,resulting in brown lesions on older leaves. Nematodediseases tend to be rare on indoor plants.

Good sanitation is the primary means of controlling thesepathogens. Soil sterilization prior to planting will kill adultsas well as eggs of root nematodes. Fumigants are aseffective as steam for this purpose. Fumigants can be usedas a nematode management tool in a production setting butare not registered for use in interior landscapes.

Material adapted from Michigan State University ExtensionBulletin E-2308 Interiorscape Pest Management. A TrainingManual for Commercial Pesticide Applicators. JulieStahecki, Editor.

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CHAPTER FOUR

INSECT MANAGEMENT IN THEINTERIORSCAPE ENVIRONMENT

'Interiorscape Mites and Insects

Most pest problems on interiorscape plants originatebecause the plants were not grown in an indoorenvironment. Once introduced to the interiorscape, manyinsects and mites will thrive, and spread to other plants. Thekey to controlling insects and mites is to remedy thesituation before permanent installation of the plants. Thereis much greater flexibility in control procedures (chemicals,application methods, etc.) in a greenhouse or even anacclimatization room than in the interiorscape.

The importance of early detection and diagnosis of theproblem cannot be overemphasized. This is the key tocontrolling nearly all pests before significant plant injury orcontrol expenses occur. Pesticides and natural enemies willcontrol most insects and mites, if correct procedures arefollowed.

'Mites

Several mite species attack plants indoors, often causingsevere injury. Most common among them is thetwo-spotted spider mite. They have a wide host range, sovery few plants are safe from attack. Adult spider mites areabout 1/50 inch long and are usually found on lower leafsurfaces. Feeding injury on many plant species involveslight-colored, speckled or mottled areas on leaves. Webbing

is also produced. Severespider mite infestations causeleaves to dry and fall fromthe plant. At 75 F, about twoweeks are required for mitesto develop from egg to adult.

Other important mites include the broad mite and cyclamenmite. Because these mites are about 1/100 inch long,infestations are recognized by plant injury symptoms ratherthan by seeing the mites. Most feeding injury occurs onyoung foliage, where injury is characterized by thickenedand brittle foliage, with leaf margins cupped downward andstunted. Many of these symptoms are characteristic of injuryby pesticides, so infestations can go unnoticed for longperiods of time. Since these mites are attracted to dustyconditions, removing dust from the plants with soapy water(which will also remove the mites) will help discouragetheir presence.

'Insects Many insects cause injury to plants indoors.

Mealybugs are very common and are difficult to control.

Several species can be foundon plants indoors, includingsome that feed on the roots.All foliar-feeding mealybugspec ies have suck ingmouthparts that remove plantfluids. A sticky honeydew isexcreted, which coats foliagebelow the infested area,attracts ants, and promotes black sooty mold growth.Damage results in stunted plant growth or death of theplant. Each female mealybug may produce several hundredeggs. The egg-to-adult cycle is 6 to 8 weeks. Movinginfested plant material into the interiorscape is virtually theonly way mealybugs become established.

Several species of scaleinsects infest plantsindoors, arriving onpreviously infestedplants. One of the mostcommon is the softbrown scale. Scales,like mealybugs, aresap-sucking insects,which also excretehoneydew. Females

produce up to 1,000 eggs underneath their protective shellor "scale." The eggs hatch into tiny crawlers, which spreadabout the plant. After dispersing, crawlers settle and feed inone location for the remainder of their lives. The length ofthe life cycle varies with each species, ranging from 1 to 8or more generations per year. Scale damage reduces plantvigor. The honeydew attracts ants and promotes the growthof a black, sooty mold.

Aphids also have piercing-suckingmouthparts and produce honeydew.They are soft-bodied, somewhatpear-shaped insects. Indoors, all aphidsare female, reproduce year round, andmultiply rapidly. Each mature femalemay produce up to 50 daughters that, inturn, will begin reproducing in 7 to 10 days. Aphidinfestations often are evident by the white cast skins that areshed by the aphids when molting. Aphids reduce plant vigorand distort leaves. The honeydew attracts ants and promotesthe growth of a black, sooty mold.

Whiteflies have piercing-suckingmouthparts which they use to suckjuices from the plants. They excretelarge quantities of honeydew.Whiteflies, especially the greenhousewhitefly, are common pests of manyornamental plants. Indoors, white fliesare most likely to be found on

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poinsettia, fuchsia, chrysanthemum, or other floweringplants brought into the location for color. All white fly lifestages develop on undersides of leaves, but the adult isusually found on the upper leaves. The egg-to-adult cycletakes 21 to 36 or more days, depending on temperature.

Thrips cause problems indoors on both foliage and flowers.These small, slender insectsare less than 1/8 inch long.They feed by rasping planttissues with their mouthpartsand consuming plant fluids.Heavily infested areas on

leaves appear silvery gray, with lighter infestations showingup as small whitish-colored areas.

Black dots of excrement also are present. Eggs are laid onor in plant tissues. The egg-to-adult cycle takes 18 to 21days. Some species of thrips leave the plant and transformto the adult in the growing medium. Thrips are difficult tocontrol indoors. Few insecticides are registered for use onplants indoors that provide effective control, unless theplants are moved to a greenhouse or outdoors prior totreatment.

Fungus gnats are small, dark gray or blackflies that resemble midges or mosquitoes.Presence of fungus gnats may indicate anoverly wet situation. The flies often gettrapped in the moisture on leaf surfaces,which detracts from the plant's appearance.Decreased aesthetic value is the greatestdamage done by adult fungus gnats; however,the larvae also damage plants by feeding on decaying orhealthy organic matter (including roots) and fungi. Fungusgnats have increased in importance recently because of theprevalence of soil-less mixes in the plant industry. Some ofthese growing media, especially those that contain peatmoss, apparently are excellent for survival of the insects.

'Control

Commercial indoor landscape accounts are perhaps the mostdifficult areas in which to attempt pest control. Interiorplantscapes extend from public conservatories to extensiveplantings in homes, hotels, office buildings, restaurants,shopping malls, hospitals, schools, and otherenvironmentally sensitive areas. The use of insecticides inthese areas is often greatly restricted because of thesensitivity of the surroundings. In addition, few chemicalsare cleared for ornamental plant use in public areas, andpublic prejudice against pesticide odors can preventapplication of pesticides in many situations.

An amazing variety of insects feed on flowering and foliageplants. The routine use of insecticides usually eliminatespredaceous insects and mites. However, pests remaining

after treatment sometimes tolerate commonly usedinsecticides. To stay in business, most commercial flowerand foliage plant growers must become fairly sophisticatedin using various types of pest management practices,insecticide formulations, application equipment, and inrotating insecticides from one chemical group to another.

COMPONENTS OF INTEGRATED PESTMANAGEMENT

'Pesticides

Thorough, timely applications of properly labeled pesticidesare another important aspect of an integrated pest controlprogram. Rotating infested plants back into a greenhousewhere they can be treated thoroughly and revived in vigorbefore being returned to the indoor landscape is a soundpractice but is often not practical. Treat commerciallandscape areas at night, on weekends, or when a minimumnumber of people are present. The public should not beallowed in the vicinity of treated plants until the pesticideresidue on the foliage has dried completely.

'Record Keeping

A written log should be kept of pest type, locality,abundance, and all pesticides applied. Such records can beof long-term benefit as many pests tend to appear at aboutthe same time each year. However, the short-term benefitsof written records may be greater. Knowing what pestssurvive a pesticide application alerts the grower to thepossibility of poor timing, poor application, or pesticideresistance in the pest population. A change in strategy,application technology, or type of pesticide can be madebefore the crops are significantly damaged.

'Biological Control

Interest in biological control in indoor landscapes hasexpanded in recent years because of restrictions placed oninterior plantscape pesticide applications, pesticide costs,poor control with pesticide products, phytotoxicity, andpotential human health hazards. To be successful atmanaging pest problems with biological control agentsrequires a knowledge of the biology of the pest species, thebiological control agent(s), and a great deal of time andcommitment. Biological control systems do not look afterthemselves.

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CHAPTER FIVE

PESTICIDE APPLICATIONS IN THEINTERIORSCAPE

Because conditions are so varied in the interiorscape, nosingle pest control program can be suggested. Chances ofsuccess using proper pesticides is possible only when thecorrect material is applied in the correct manner to asusceptible stage of the pest.

Maintenance or preventative sprays may be applied everyone to three weeks, depending upon the pest, time of year,and residual activity of a pesticide. An effectivemaintenance spray program should control any initialinvaders and prevent pest populations from developing. Itis much easier to maintain pest-free plants than to controlestablished populations. If a preventative program is notused, it will be necessary to inspect plants closely atfrequent intervals and apply control measures before pestsreach damaging levels.

'Spray Applications

Many pesticides are broken-down(hydrolyzed) in the spray tank whenmixed with water above pH 7. Beaware of the water pH and whenabove 7 a buffering solution shouldbe added to maintain pH in the 6.5to 7 range.

Sprays should be applied only to thoroughly wet the foliage.Excessive volume of any pesticide may cause phytotoxicity.Both leaf surfaces, especially the underside, must besprayed. Proper mixing by adequate mechanical agitationin the spray tank is necessary for best results. For safety andefficacy pesticides should be applied the same day they aremixed with water.

To obtain better coverage and residual persistence of thepesticide, a spreader-sticker may be recommended. Read thecontainer label and use the material at the concentrationspecified by the manufacturer. If you are using a newspreader-sticker, be careful to evaluate it for any phytotoxiceffects.

'Granular Applications

All granular materials should be applied in a manner toinsure even distribution over the soil surface. DO NOTapply them to wet foliage. Following surface application ofgranular pesticides, the soil surface should be wateredthoroughly to leach the pesticide into the upper layer of soil.This precaution will make the pesticide quickly available tothe plants and position the granules where they are lesslikely to be contacted by those using the building.

'Compatibility

Spray tank mixtures of insecticides, miticides or fungicidesmay result in plant injury that does not occur from use ofany one of the materials alone. Before materials are tankmixed, acompatibility chart should be consulted and themanufacturer's label studied carefully.

'Phytotoxicity

Phytotoxicity is generally characterized as damage tofoliage, usually exhibited as marginal burn, chlorosis orspotting. Distortion or abnormal growth is also a commonsymptom of plants injured by pesticides. Although anyportion of the plant may be affected, the new growth is mostlikely to show damage.

Because many plantscapes are usually located adjoininglarge glass areas, plant damage can be minimized whenpesticides are applied during the cooler part of the day.Although wettable powders are considered safer to plantsthan emulsifiable concentrates, they frequently leaveobjectionable residues on the foliage.

Read the label for plants that are sensitive to the pesticide.Regardless of the pesticide or mixture of pesticides used, itis strongly recommended that the effects be evaluated on afew plants, under your particular condition before treatingall plants. There may be several formulations of a chemicalcompound available. Concentrations vary and consequentlyrecommendations on the manufacturer's label should befollowed explicitly.

'Warning

All pesticides must be handled with caution.Safety precautions, including the use of properprotective equipment, printed on the label mustbe followed. Be sure pesticides are labeled forinteriorscapes and that you have a label in possession. Readthe entire label, including the small print, before openingthe container. Allow plenty of time after applyingpesticides so plants are completely dry before people arepresent in the area. To prevent contamination of non-targetareas (pools, seating and food areas, etc.) use low pressure,spray only to point of glisten and use plastic drop cloths.

Drop cloths used for shielding purposes should be handledcarefully to avoid exposure. Store pesticides in their originallabeled containers, out of reach of children, irresponsiblepeople, pets, and preferably keep pesticides under lock andkey. When containers are empty, rinse with water severaltimes and pour rinsing into spray tank. Dispose of emptycontainers promptly and safely.