2014 Getting Started in the Greenhouse Business

T. Michael Likins County Agent

Chesterfield

IPM in the Greenhouse: Diseases

Learning objectives

Understand components of disease Understand sources of disease

Organisms cause diseases Conditions influence diseases

Believe Botrytis is your worst enemy Recognize different symptoms

root rots, mildews, bacteria, viruses Understand resistance management

Handouts

Botrytis of Ornamental Plants UIUC

Impatiens downy mildew VA Cooperative Extension

Selected Fungicides for Greenhouse Use NE Vegetable Management Guide

Biofungicides VA Cooperative Extension

Virus Diseases of Floral Crops OSU Cooperative Extension

Plant Disease

Dynamic system Interactions determine disease Controls address interactions

Plant Pathogen

Environment

Plant Pathogen

Environment

Exclusion

Sanitation

Integrated Pest Management

Eradication

Resistance

Chemicals

Biological Control

Stress Management

Greenhouse Environment

Consistency (good or bad) Environment = disease Humidity Temperature Crowded plant spacing Lush growth

Managing GH Diseases

Accurate diagnosis No matching Google images

Understanding pathogen sources Understanding pathogen biology Field diagnoses may not be possible Laboratory confirmation necessary

Disease sources

PATHOGENS ARE CONTAGIOUS! Infested soil or mix Previous crop Plants kept all year Vegetatively propagated plants Water Air

Fungal hypha

Nematode (head) Nucleus

Cell wall

Beet yellows virus Tobacco mosaic virus

Wheat striate mosaic virus Cucumber mosaic virus

Tobacco necrosis satellite virus Hemoglobin molecule

Viroids

Phytoplasmas

Bacterium

Nucleolus

Agents of Anguish

Botrytis in all its forms… Gray mold!

• First described in 1729 • Extensive host range

• Almost all herbaceous plants • Woodies, too, (fir, maples, rhodies)

• 1530 U.S.D.A records • 13 +/- species of concern • Attacks susceptible tissue

• Senescing, weakened, wounded, FLOWERING

Botrytis’ symptoms on various plants

Leaf Spots or Blights Cankers or Shoot Blights

Bud Blast or Flower Blights

Fruits or Bulb Rot

Beet Pansy Anemone Chrysanthemum Bean Begonia Peony Asparagus Dahlia Cucurbits Chicory Pepper Calendula Dogwood Eggplant

Crucifers Periwinkle Chrysanthemum Geranium Grape Cucurbits Potato Fuchsia Hydrangea Onion Dogwood Rhubarb Geranium Marigold Pepper Eggplant Rutabaga Heather Peony Raspberry Endive Shallot Hydrangea Petunia Strawberry

Geranium Tomato Peony Rose Tomato Hawthorn Tulip Periwinkle Sunflower Tulip Hydrangea Turnip Rose Sweet Pea

Lettuce Violet Snapdragon Tulip Onion Tulip Zinnia

Botrytis cinerea

Botrytis blight of Geranium

Botrytis control Don’t give it what it wants!

Disease is favored by High RH (85-100%) Low temperatures (45° to 60° F)

HAF fans eliminate cool spots Be careful, though!

Fungicides (plural)

Questions about Botrytis?

• Pathogens: • Pythium spp. • Rhizoctonia solani • Fusarium spp.

• Hosts • Seedlings of virtually anything

• Requires laboratory confirmation

Damping-Off

Damping-Off

• Control – Moderate soil moisture

• Use a soil with adequate drainage • Don’t overwater

– Germinate seeds at higher temperatures – Use fungicides to protect seedlings

• Seed treatment or drench

Root Rots

• Thielaviopsis basicola, black root rot • Pythium spp., • Phytophthora spp., • Rhizoctonia solani, • Fusarium spp. • Hosts

– Virtually anything – Greenhouse: Poinsettia, Pansy, Petunia

Geranium, Begonia

Root Rots

• Control – Sterilized potting medium – Moderate soil moisture

• Use medium with adequate drainage • Don’t overwater

– Use fungicides to prevent infections

Root Rots

• Control – Decontaminate recycled water

• Filtration • Irradiation • Chemical treatment

Powdery Mildews

• Erysiphe sp., Microsphaera sp., Uncinula sp., Sphaerotheca sp., Phyllactinia sp., Podosphaera sp. (Oidium sp., Ovulariopsis sp.)

• Hosts – Virtually everything – Greenhouses: Grape-leaf ivy, oak-leaf ivy,

jadeplant, zinnia

Powdery mildew

Powdery Mildews

• Control – Remove diseased plant material/ debris – Reduce humidity – Use fungicides to prevent infections – Resistant varieties

Impatiens downy mildew

Fungus-like disease Plasmopara obducens

2004 Sporadic since then

2011 summer outbreaks 2012 Chesterfield, et. al. 32 states and D.C.

Extremely contagious Spores easily dislodged

Local spread Splashing water

Long distance spread Wind currents

Impatiens downy mildew

Susceptible varieties Impatiens walleriana Common garden impatiens

Interspecific hybrids, too Resistant varieties (High tolerance) New Guinea and Sunpatiens

Impatiens downy mildew

September 2011

September 2012

September 2012

September 2012

Impatiens

Downy Mildew

September 2013

Impatiens downy mildew recommendations

• Monitor • Subtle chlorosis or stippling • Flagging, curling or drooping • Defoliation

• Remove DM-positive plants immediately • Fungicides for prevention only • New Guinea impatiens as replacement

• Begonia, coleus,

Bacteria

Diagnosis

XCP

Practical Tests for Identifying Bacteria Bacterial wilt of tomato

Ralstonia solanacearum Soil borne Diagnostic equipment

test tube water

• Bacterial wilt of cucurbits • Erwinia tracheiphila • Plant debris and insects • Diagnostic equipment

• pocket knife

XCP

Xanthomonas campestris pv. pelargonii Affects zonal cuttings and seedlings Affects ivy geraniums

Symptoms of Bacterial Blight of Geraniums

V-shaped wedges with yellow haloes (1º) Spots within a wedge Wilting Tiny, round brown spots (2º)

Images of symptoms

V-shaped lesions

Spots within wedge

Tiny, brown spots

Wilting

Control of XCP

SANITATION remove plants with symptoms don’t compost sterilize containers for reuse

Wash hands with soap & water Keep shipments separated (exclusion) Separate seedlings from cutting crop Don’t use capillary mats Phyton 27 (?)

Life After XCP

Do not overwinter geranium stock No geraniums in GH for 3 months Disinfestation of GH surfaces 10% solution of 5.25% NaOCl 1 part agricultural bleach + 9 parts H2O tincture of time . . . 10 minutes!

Certified, XCP-indexed plants Monitor

Xanthomonas Leaf Diseases

• Cause: Xanthomonas campestris – pv. poinsettiicola – pv. hederae – pv. begoniae – pv. dieffenbachiae – pv. pelargonii

• Hosts: – Poinsettia – Ivies – Begonia – Dumbcanes

et al. – Geranium

Xanthomonas leaf diseases

• Control: – Start with clean propagation materials – Follow strict sanitation procedures when

working with plant materials – Remove symptomatic plants – Remove contaminated plant debris – Disinfest greenhouses after production

Bacterial Wilt

• Cause: Ralstonia solanacearum – races – biovars

• Hosts: – Geranium – Tomato – Many other hosts

Bacterial Wilt

• Control: – Start with clean propagation materials – Follow strict sanitation procedures when

working with plant materials – Remove symptomatic plants – Remove contaminated plant debris – Disinfest greenhouses after production

Viral Plant Diseases

• Causes – Impatiens necrotic spot virus (INSV) – Tomato spotted wilt virus (TSWV) – Tobacco mosaic virus (TMV) – Cucumber mosaic virus (CMV) – Dasheen mosaic virus (DsMV) – Cymbidium mosaic virus (CyMV) – Odontoglossum ringspot virus (ORSV)

Viruses

Smallest pathogens Difficult to see; easier to diagnose Symptoms include Yellowing Stunting Abnormal/deformed growth Mosaics Ring patterns

Viruses

Fig mosaic virus Canna yellow mosaic virus Rose mosaic virus Hosta virus X

Fig mosaic virus

Canna yellow mosaic virus

Apple Mosaic Virus Betula spp.

(apple line pattern)

Rose Mosaic Complex Apple mosaic virus Prunus necrotic ring spot virus

Hosta virus X

Viral Plant Diseases

• Control: – Start with clean propagation materials – Follow strict sanitation procedures

when working with plant materials – Remove symptomatic plants – Remove contaminated plant debris – Remove potential weed hosts – Control insect vectors

In SUMMARY…

EXCLUDE PREVENT ERADICATE

Resistance reported

Benomyl Benlate (1968) 1973 Copper 1958 Carboximides Captan (1949) 1982 Mg carbamates Manzate (1950) 1959 Iprodione Chipco 26019 (1970) 1986 Thiophanate-methyl Cleary’s 3336 (1969) 1970

Fungicide Resistance Management

Fungicide

REI (hrs)

FRAC code

MOA

Bacillus subtillus* Serenade, Rhapsody 4 44 lipids, membranes copper hydroxide Kocide 24 M1 multi-site copper sulfate, basic* Cuprofix 24 M1 multi-site copper salts Camelot 12 M1 multi-site dicloran Botran 12 14 lipids, membranes horticultural oil* Ultra-fine 4 n/c not classified hydrogen dioxide* Zerotol 0 n/l not listed mancozeb Dithane F-45 24 M3 multi-site PCNB Terraclor 12 14 lipids, membranes potassium bicarbonate* Armicarb, Kaligreen 4 n/c not classified propamocarb HCl Previcur Flex 12 28 lipids, membranes pyrimethanil Scala 12 9 amino acids, proteins streptomycin sulfate Agri-mycin 12 25 amino acids, proteins sulfur* Microthiol 24 M2 multi-site * = some formulations OMRI approved

Selected Fungicides / Bacteriocides Labeled for Greenhouse Vegetable Use

Remember…

…don’t get caught with your plants down,

consult a plant pathologist!

Thank you.

Questions???

Foliar Nematodes

Symptomatology

Biology

Control (?)

Detection

Foliar Nematodes

• Cause: Aphelenchoides ssp. • Hosts

– Wide host range – Greenhouse: African violets, ferns,

begonia, chrysanthemum

Symptomatology Vein-limited Depends on host species Often a "chevron" pattern

Green Pie Crust

White Christmas

Crusader

Biology of Foliar Nematodes

Ecto- & endo-parasites feed on leaf parenchyma

Capable of survival Overwinter on vegetative material Seeds detritus A. fragariae can survive 3 years in

dried grains

Invasion through stomata

Foliar Nematodes

Aphelenchoides spp. a.k.a. Bud & leaf nematodes

a.k.a. Stem, flower, fruit, & bulb nematode

105 recognized species, 3 of which are important A. ritzemabosi A. fragariae A. besseyi

Control

Sanitation Avoid overhead irrigation Resistance (???) Hot water & steam Chemicals Nemacur® 10G Oxymyl (Vydate®) Pylon® for greenhouses

Certified, disease-free material

CLINIQUE TECHNIQUE

Foliar Nematodes

• Control: – Start with clean propagation

materials – Follow strict sanitation procedures

when working with plant materials – Remove symptomatic plants – Remove contaminated plant debris – Avoid overhead irrigation