The Who and What of Greenhouse Problems!

Objective 11.00

11.01: Explain potential problems related to bedding plant production

11.02: Hypothesize causes of problems with bedding plants

11.03: Propose possible solutions to problems with greenhouse plant production

Potential Problems (Click to view)

Cultural Disorders• Germination Problems• Fertilization Problems• Uneven growth• Tall and spindly growth

Diseases• Seedlings falling over• Lower leaves brown, rotting, and drying

Insects• Plants missing• Holes in leaves or plant parts missing

Cultural Disorders

A cultural disorder is anything that can cause a plant a problem but is not caused by a type of pest (disease, weed, or insect)

Cultural-Germination Problems

Causes Improper temperaturesOver-watering or underwateringChemical residues in mediumSeed planting depthLow quality seeds

Cultural-Germination Problems

Correction or PreventionUse high-quality seedsPlant at proper depth Use medium with no chemical residuesMaintain proper temperaturesMaintain proper moisture levels

Cultural-Fertilization Problems

Causes Lack of nutrients Root injury Improper pH of

medium Excessive

fertilization

Manganese Deficiency

Cultural-Fertilization Problems

Correction or PreventionTest soil or mediaApply correct amounts and kinds of

nutrientsUse pH correcting materials

Cultural-Uneven Growth

CausesPoor mixing of mediumUneven moisture levelsUnlevel flatsPoor grading of seedlings

Cultural-Uneven Growth

Correction or PreventionProper mixing of mediaEven wateringGrading seedlings by size and qualityPlacing flats level

Cultural-Tall and Spindly Growth

CausesToo much nitrogen fertilizerOverwateringLow light intensity (too much shade)High temperatures

Cultural-Tall and Spindly Growth

Correction or PreventionUse the correct amount of nitrogenReduce frequency of wateringLower temperatureProvide more lightUse growth retardant such as B-Nine SP

Cultural-Slime or Algae

Causes Too much watering

Cultural-Slime or Algae

Correction or PreventionWater less oftenClean out fertilizer tanksDon’t leave any standing water

Diseases

Help me! I’m dying.

Disease

An abnormal condition of an organism that impairs plant functions

Disease

Disease is a plant disorder caused by an infectious pathogen or agent

Three Conditions Necessary for Diseases

Host plantDisease causing organism or pathogen

must be presentFavorable environment for disease

organism to develop

Groups of pathogens

Bacteria Fungi Viruses Parasitic plants-

mistletoe, dodder, lichens (attach to plants)

Plant Disease

Must be identified before they can be treated

Warm temperatures and moist conditions in greenhouse plant production make most horticulture plant diseases worse

Disease

Preventing plant disease through sanitation and insect control is much easier than treating the disease.

Diseases

Blight Canker sores Damping off Galls Leaf spot Mildew

Mosaic Rots Rust Smut Wilt

Diseases-Seedlings Falling Over

Causes Stem rot Damping-off

Diseases-Seedlings Falling Over

Correction or PreventionUse sterilized mediaApply fungicides Improve air circulation around plants

Diseases-Brown, rotting leaves

Causes Botrytis

a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes

Diseases-Brown, rotting leaves

Correction or Prevention Increase air temperature Increase air circulation around plantsUse proper fungicide

Damping off

Fungal disease Causes young plants

and seedling to rot off at soil level

Mildew

Grows on leaf surfaces

Upper and lower leaves

Appears as white, gray or purple spots

Example is powdery mildew

Mosaic

Caused by a virus Leaves have

irregular mottled areas with patterns

Ranges from dark green to light green to yellow to white

Rots

Causes plants to decay and die

Usually has a unique smell

Rust

Causes small spots on leaves

Resembles yellow, orange, brown or red rust

Mainly on underneath of leaf

An arthropod with three pairs of legs and three body regions; insects may have one or two pairs of wings

Insects

Insects-Plants Missing

Causes Slugs Snails Cockroaches

Insects-Plants Missing

Correction or Prevention Use baits and

pesticides

Insects-Holes in Leaves

Causes Aphids Mealy Bugs Scale Insects Thrips Whiteflies Flea beetles Fungus Gnats

Leaf miners Cutworms Caterpillars

Insects-Holes in Leaves

Correction or Prevention Use of

recommended pesticides to control insects

Insect bad guys!

You’ll never look at a bug the same.

Damage

Damage depends on the type of mouthpart

Chewing Sucking

Chewing- Beetles

Eat leaves Stems Flowers Fruits Nuts

Beetles

CorrectionOil or soap

Chewing- Caterpillars

Larva Moths Butterflies Fuzzy and hair Eat young leaves

and stems Roll up in leaves,

makes leaves curl

Caterpillars

CorrectionTent Caterpillars-kerosene to burn them

Sucking- Aphids

Pierce and suck juices

Plant lice Cause stunted

growth, yellow spotted leaves

Sticky substance and black mold

Attracts ants

Aphids

CorrectionApple Cider VinegarOil or SoapMalathionLady bugs

Sucking- Mealy Bugs

Pierce and suck from underside of leaves

Suck in leaf axils Causes yellow

appearance Sticky secretions

Mealy Bug

CorrectionsOil or soapNeem

Sucking- Thrips

Chews and then sucks

Causes plant tissue to become speckled or whitened

Leaf tip withers Leaf curls and dies

Thrips

Correction Insecticidal Soap

Sucking- Whiteflies

Feeds on underside of young leaves

Little flying white specks when plants are shaken

Whiteflies

CorrectionMarathonLady bugs

Sucking- Mites

Attack underside of leaf

Causes leaves to turn gray to grayish

Severe infestations cause webbing

Insects can be red

Slugs & Snails

ProblemsPlants Missing

Slugs & Snails

Correction or PreventionUse baits and pesticidesBeerCaffeine (Coffee)