Plant Problem Diagnosis Key / Diseases
Mosaic viruses
Tobamovirus (TMV, ToMV, ToBRFV), Cucumovirus (CMV) and others
Viruses that mottle and distort leaves. Tobamoviruses spread on hands, tools and plant contact and survive for years in plant debris and soil; cucumber mosaic is spread by aphids. Infected plants stay infected.
Signs
- Light and dark green patches in a mosaic on the leaf.
- Curled, distorted or narrow leaves; stunted plants.
- Wrinkled, bumpy or mottled fruit that ripens unevenly.
What favors it
Hands and tools that have touched infected plants (tobamoviruses), aphids (cucumber mosaic), and infected seed.
Prevention
- Grow varieties resistant to TMV and ToMV, and to CMV in cucurbits and peppers.
- Keep hands clean and sanitize tools and work surfaces.
- Use clean seed and transplants.
Often confused with
Sources
- Tobamoviruses that affect tomato (TMV, ToMV, ToBRFV)NC State Extension
- Odd Symptoms in Tomato Plants Turn Out to be VirusesUniversity of Maryland Extension
- Cucumber Mosaic VirusUMass Amherst Extension
Treatment by crop
Cultural, biological and chemical options in the order to use them, and notes written for each crop.
Identification is free. Treatment is on the Home and Pro plans.
Questions in the key that lead here
- Look the plant over, leaf undersides included. Are insects, mites, slugs, eggs, webbing or droppings on it?
No, only damage or discoloration - Where is the problem?
Leaves - What does the leaf damage look like?
Color change without distinct spots - Where did the color change start?
Across the whole plant, or in patches - What does the change look like?
Light and dark green mosaic, leaves curled or distorted
Not a match? Start the key or describe what you see.
More photos
More from university Extension: search Extension pages on mosaic viruses, or find a plant diagnostic lab through your state's Extension.
Other diseases
- Anthracnose
- Apple scab
- Bacterial leaf scorch
- Bacterial leaf spot
- Bacterial wetwood (slime flux)
- Bacterial wilt of cucurbits
- Black knot
- Black spot of rose
- Bleeding canker
- Boxwood blight
- Canker diseases
- Cedar-apple and related rusts
- Crown gall
- Damping-off
- Downy mildew
- Dutch elm disease
- Early blight and Alternaria leaf spot
- Elm yellows (phloem necrosis)
- Fire blight
- Fusarium wilt
- Gray mold (Botrytis)
- Late blight
- Needle cast and tip blight
- Oak wilt
- Powdery mildew
- Root and butt rot
- Root rot (Pythium and Phytophthora)
- Rust
- Septoria leaf spot
- Shade tree anthracnose
- Sooty mold
- Tar spot of maple
- Tomato spotted wilt and impatiens necrotic spot viruses
- Verticillium wilt
- White mold (Sclerotinia)
- White pine blister rust