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
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
Causal agent: Clavibacter michiganensis subspecies michiganensis
Pathogen type: Bacterium
Management: The use of pathogen-free seeds.
Photo credit: Morgan Goodnight
Birch Sawfly Larvae
Causal agent: Cimbex femoratus
Pathogen type: Insect
Management: Tolerate it.
Photo credit: James Glenn
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
Causal agent: Insufficient calcium
Pathogen type: Abiotic
Management: Fertilization
Photo credit: Dhruba Dhakal
Blue Winged Wasp
Causal agent: Scolia dubia
Pathogen type: Insect
Management: Beneficial pollinator. No need to control.
Cedar-apple Rust on Juniper
Causal agent: Gymnosporangium spp.
Pathogen type: Fungi
Management: No need to control
Photo credit: MU-PDC client
Cedar-hawthorn Rust
Causal agent: Gymnosporangium globosum
Pathogen type: Fungi
Management: No need to control
Photo credit: Katie Kammler
Cedar-quince Rust
Causal agent: Gymnosporangium clavipes
Pathogen type: Fungi
Management: No need to control
Photo credit: Patrick Byers
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
Causal agent: Crioceris asparagi
Pathogen type: Insect
Management: Biological control and insecticide
Photo credit: Debi Kelly
Common Orange Lichen
Causal agent: Xanthoria parietina
Pathogen type: Lichen
Management: No need to control.
Photo credit: James Glenn
Eight-spotted Forester Caterpillar
Causal agent: Alypia cotomaculata
Pathogen type: Insect
Management: No need to control.
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
Causal agent: Aproceros leucopoda
Pathogen type: Insect
Management: Eradication and pesticide
Photo credit: Heather Huntington
Fall Webworm
Causal agent: Hyphantria cunea
Pathogen type: Insect
Management: Not necessary if not severe.
Photo credit: TreeSMARTtrade
Flatheaded Wood Borers
Causal agent: Buprestidae
Pathogen type: Insect
Management: Prevention and sanitation
Giant Swallowtail
Causal agent: Papilio cresphontes
Pathogen type: Insect
Management: Chemical control applies to commercial citrus grower
Hackberry Nipple Galls
Causal agent: Pachypsylla celtidismamma
Pathogen type: Insect
Management: Insignificant damage and no effective way to control
Heat Stress
Causal agent: Environmental stress
Pathogen type: Abiotic
Management: Good irrigation
Hollyhock Rust
Causal agent: Puccinia heterospora
Pathogen type: Fungi
Management: Preventative fungicide application and sanitation
Photo credit: Katie Kammler
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)
Causal agent: HVX
Pathogen type: Virus
Management: Use virus free plants
Iron Chlorosis
Causal agent: Iron deficiency and high PH
Pathogen type: Abiotic
Management: Fertilization
Photo credit: Katie Kammler
Japanese Maple Scale
Causal agent: Lopholeucaspis japonica
Pathogen type: Insect
Management: Sanitation, dormant oil and insecticide
Photo credit: Morgan Goodnight
Juniper Bagworms
Causal agent: Thyridopteryx ephemeraeformis (Haworth)
Pathogen type: Insect
Management: Hand-pick
Photo credit: Morgan Goodnight
Knopper Galls on Oak
Causal agent: Andricus quercuscalicis
Pathogen type: Insect
Management: No need to control.
Photo credit: James Glenn
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
Causal agent: Oxyopidae spp.
Pathogen type: Insect
Management: No need to control
Mealybugs
Causal agent: Planococcus spp.
Pathogen type: Insect
Management: Biological control and insecticide
Photo credit: Katie Kammler
Pear Rust (Cedar-hawthorn Rust)
Causal agent: Gymnosporangium globosum
Pathogen type: Fungi
Management: Preventative fungicide application and sanitation
Potassium Deficiency
Causal agent: Potassium deficiency
Pathogen type: Abiotic
Management: Soil test and fertilization
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
Causal agent: Podosphaera spp. or Erysiphe spp.
Pathogen type: Fungi
Management: Neem oil, milk, baking soda
Scales on Philodendron
Causal agent: Scales
Pathogen type: Insect
Management: Sanitation, dormant oil and insecticide
Photo credit: Katie Kammler
Soybean Target Spot
Causal agent: Corynespora cassiicola
Pathogen type: Fungi
Management: Fungicide and resistant cultivar
Spittlebugs on Mint
Causal agent: Philaenus spp.
Pathogen type: Insect
Management: No significant damage. A quick blast of water.
Photo credit: Katie Kammler
Squash Bug
Causal agent: Anasa tristis spp.
Pathogen type: Insect
Management: Pick off early and insecticide.
Tar Spot of Maple
Causal agent: Rhytisma spp.
Pathogen type: Fungi
Management: Preventative fungicide application and sanitation.
Tomato White Mold
Causal agent: Sclerotinia sclerotiorum
Pathogen type: Fungi
Management: Sanitation
Photo credit: MU-PDC client
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
Causal agent: Arilus cristatus
Pathogen type: Insect
Management: Beneficial insects. No need to control.
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
Causal agent: Cinara strobi
Pathogen type: Insect
Management: Neem oil and insecticidal soap
Photo credit: MU-PDC client
Woolly Bear Caterpillar
Causal agent: Pyrrharctia Isabella
Pathogen type: Insect
Management: No need to control.