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Disease snapshots

These disease snapshots cover a broad range of plant diseases such as fungi, bacteria, viruses, insects and abiotic stresses. By presenting a representative digital image and a brief description, the MU Plant Diagnostic Clinic aims to provide you with a quick and accurate diagnosis to solve your plant problems. In contrast to sample highlights, this section may include some insignificant but very interesting plant diseases that could broaden your knowledge of plant pathology.

  • American Dagger Caterpillar

    american dagger caterpillar

    Causal agent: Acronicta americana
    Pathogen type: Insect
    Management: Beware!! Poisonous!! Look it up before you pick it up.
    Photo credit: MU-PDC client

  • Bacterial Canker of Tomato

    bacterial canker of tomato

    Causal agent: Clavibacter michiganensis subspecies michiganensis
    Pathogen type: Bacterium
    Management: The use of pathogen-free seeds.
    Photo credit: Morgan Goodnight

  • Birch Sawfly Larvae

    birch sawfly larvae

    Causal agent: Cimbex femoratus
    Pathogen type: Insect
    Management: Tolerate it.
    Photo credit: James Glenn

  • Black Scale on Jasmine

    black scale on jasmine

    Causal agent: Saissetia oleae
    Pathogen type: Insect
    Management: Scrape the scale off or use insecticidal soap.

  • Blossom-end Rot of Tomato

    blossom end rot

    Causal agent: Insufficient calcium
    Pathogen type: Abiotic
    Management: Fertilization
    Photo credit: Dhruba Dhakal

  • Blue Winged Wasp

    blue winged wasp

    Causal agent: Scolia dubia
    Pathogen type: Insect
    Management: Beneficial pollinator. No need to control.

  • Cedar-apple Rust on Juniper

    cedar apple rust

    Causal agent: Gymnosporangium spp.
    Pathogen type: Fungi
    Management: No need to control
    Photo credit: MU-PDC client

  • Cedar-hawthorn Rust

    cedar hawthorn rust

    Causal agent: Gymnosporangium globosum
    Pathogen type: Fungi
    Management: No need to control
    Photo credit: Katie Kammler

  • Cedar-quince Rust

    cedar quince rust

    Causal agent: Gymnosporangium clavipes
    Pathogen type: Fungi
    Management: No need to control
    Photo credit: Patrick Byers

  • Cicada Damage

    cicada damage

    Causal agent: Cicada bugs
    Pathogen type: Insect
    Management: Removal of damaged branch, cover small tree with netting
    Photo credit: Katie Kammler

  • Common Asparagus Beetle

    common asparagus beetle

    Causal agent: Crioceris asparagi
    Pathogen type: Insect
    Management: Biological control and insecticide
    Photo credit: Debi Kelly

  • Common Orange Lichen

    common orange lichen

    Causal agent: Xanthoria parietina
    Pathogen type: Lichen
    Management: No need to control.
    Photo credit: James Glenn

  • Eight-spotted Forester Caterpillar

    eight-spotted forester caterpillar

    Causal agent: Alypia cotomaculata
    Pathogen type: Insect
    Management: No need to control.

  • Elm Cockscomb Gall

    elm cockscomb gall

    Causal agent: Cockscomb gall aphid (Colopha compressa)
    Pathogen type: Insect
    Management: No need to control as the galls don't cause significant damage.

  • Elm Zigzag Sawfly

    elm zigzag sawfly

    Causal agent: Aproceros leucopoda
    Pathogen type: Insect
    Management: Eradication and pesticide
    Photo credit: Heather Huntington

  • Fall Webworm

    fall webworm

    Causal agent: Hyphantria cunea
    Pathogen type: Insect
    Management: Not necessary if not severe.
    Photo credit: TreeSMARTtrade

  • Flatheaded Wood Borers

    flatheaded wood borers

    Causal agent: Buprestidae
    Pathogen type: Insect
    Management: Prevention and sanitation

  • Giant Swallowtail

    giant swallowtail

    Causal agent: Papilio cresphontes
    Pathogen type: Insect
    Management: Chemical control applies to commercial citrus grower

  • Hackberry Nipple Galls

    hackberry nipple galls

    Causal agent: Pachypsylla celtidismamma
    Pathogen type: Insect
    Management: Insignificant damage and no effective way to control

  • Heat Stress

    heat stress

    Causal agent: Environmental stress
    Pathogen type: Abiotic
    Management: Good irrigation

  • Hollyhock Rust

    hollyhock rust

    Causal agent: Puccinia heterospora
    Pathogen type: Fungi
    Management: Preventative fungicide application and sanitation
    Photo credit: Katie Kammler

  • Horned Oak Gall

    horned oak gall

    Causal agent: Callirhytis comigera
    Pathogen type: Insect
    Management: Insignificant damage and no effective way to control
    Photo credit: MU-PDC client

  • Hosta Virus X (HVX)

    hosta virus x

    Causal agent: HVX
    Pathogen type: Virus
    Management: Use virus free plants

  • Iron Chlorosis

    iron chlorosis

    Causal agent: Iron deficiency and high PH
    Pathogen type: Abiotic
    Management: Fertilization
    Photo credit: Katie Kammler

  • Japanese Maple Scale

    japanese maple scale

    Causal agent: Lopholeucaspis japonica
    Pathogen type: Insect
    Management: Sanitation, dormant oil and insecticide
    Photo credit: Morgan Goodnight

  • Juniper Bagworms

    juniper bagworms

    Causal agent: Thyridopteryx ephemeraeformis (Haworth)
    Pathogen type: Insect
    Management: Hand-pick
    Photo credit: Morgan Goodnight

  • Knopper Galls on Oak

    knopper galls on oak

    Causal agent: Andricus quercuscalicis
    Pathogen type: Insect
    Management: No need to control.
    Photo credit: James Glenn

  • Lace Bug on Oak

    lace bug on oak

    Causal agent: Corythucha arcuata
    Pathogen type: Insect
    Management: High pressure water spray and application of insecticidal soaps and horticultural oil and pesticide.
    Photo credit: James Glenn

  • Lynx Spider

    lynx spider

    Causal agent: Oxyopidae spp.
    Pathogen type: Insect
    Management: No need to control

  • Mealybugs

    mealybugs

    Causal agent: Planococcus spp.
    Pathogen type: Insect
    Management: Biological control and insecticide
    Photo credit: Katie Kammler

  • Pear Rust (Cedar-hawthorn Rust)

    pear rust

    Causal agent: Gymnosporangium globosum
    Pathogen type: Fungi
    Management: Preventative fungicide application and sanitation

  • Potassium Deficiency

    potassium deficiency

    Causal agent: Potassium deficiency
    Pathogen type: Abiotic
    Management: Soil test and fertilization

  • Powdery Mildew on Bee Balm

    powdery mildew on bee balm

    Causal agent: Golovinomyces monardae
    Pathogen type: Fungi
    Management: Proper sunlight, irrigation and fungicide
    Photo credit: Katie Kammler

  • Powdery Mildew of Peperomia

    powdery mildew of peperomia

    Causal agent: Podosphaera spp. or Erysiphe spp.
    Pathogen type: Fungi
    Management: Neem oil, milk, baking soda

  • Scales on Philodendron

    scales on philodendron

    Causal agent: Scales
    Pathogen type: Insect
    Management: Sanitation, dormant oil and insecticide
    Photo credit: Katie Kammler

  • Soybean Target Spot

    soybean target spot

    Causal agent: Corynespora cassiicola
    Pathogen type: Fungi
    Management: Fungicide and resistant cultivar

  • Spittlebugs on Mint

    spittlebugs

    Causal agent: Philaenus spp.
    Pathogen type: Insect
    Management: No significant damage. A quick blast of water.
    Photo credit: Katie Kammler

  • Squash Bug

    squash bug

    Causal agent: Anasa tristis spp.
    Pathogen type: Insect
    Management: Pick off early and insecticide.

  • Tar Spot of Maple

    tar spot of maple

    Causal agent: Rhytisma spp.
    Pathogen type: Fungi
    Management: Preventative fungicide application and sanitation.

  • Tomato White Mold

    tomato white mold

    Causal agent: Sclerotinia sclerotiorum
    Pathogen type: Fungi
    Management: Sanitation
    Photo credit: MU-PDC client

  • Virgin Tiger Moth

    virgin tiger moth

    Causal agent: Grammia virgo
    Pathogen type: Insect
    Management: No need to control. We don’t do that to anything associated with “tiger” in Missouri.

  • Wheel Bug Nymph

    wheel bug nymph

    Causal agent: Arilus cristatus
    Pathogen type: Insect
    Management: Beneficial insects. No need to control.

  • White Fly on Christmas Cactus

    white fly on christmas cactus

    Causal agent: Aleyrodidae spp.
    Pathogen type: Insect
    Management: Biological control or pesticide application.
    Photo credit: James Glenn

  • White Pine Aphid

    white pine aphid

    Causal agent: Cinara strobi
    Pathogen type: Insect
    Management: Neem oil and insecticidal soap
    Photo credit: MU-PDC client

  • Woolly Bear Caterpillar

    woolly bear caterpillar

    Causal agent: Pyrrharctia Isabella
    Pathogen type: Insect
    Management: No need to control.