No final statistics exist on how many species are attacked by Verticillium wilt, but horticulturalists and plant pathologists know that at least 300 genera are affected.
There are two species of Verticillium wilt. One type (Verticillium albo-atrum) attacks herbaceous plants (annuals and perennials) and the other (Verticillium dahliae) attacks woody plants.
This fungal disease may be confused with other fungal and bacterial diseases, particularly fusarium wilt, bacterial wilt, root rot, drought problems, and damage from too much moisture in the soil.
Verticillium Wilt Symptoms
Plant leaves wilt or curl. They may also turn yellow or red between the veins. Leaves and entire branches may be lost. Eventually, chances are that the plant will die.
Origins of Verticillium Wilt
The disease begins with fungal spores in the soil. Although they exist naturally in the soil, outbreaks can be triggered by environmental events.The fungus invades the roots and progresses upward through the xylem. Part of the destructive process is the clogging of the xylem vascular system.
The xylem tissue and sap become discolored before aboveground symptoms appear.
Plants Susceptible to Verticillium Wilt
The susceptibility of plants may differ with region, climate, adaptability and even genetic resistance. Cultural practices and environmental conditions may also have some effect on plant susceptibility.
Varieties Resistant to Verticillium Wilt
There are plants which have developed resistance to Verticillium wilt. Some have been genetically bred to be resistant. Others have adapted their own resistance.
Avoiding Verticillium Wilt
Although there is no treatment for Verticillium wilt, there are some practices that may help avoid it.
- Choose adaptive or genetically resistant varieties.
- Avoid injuries to the roots or to the plant collar.
- Keep plants healthy by proper watering and use of organic fertilizers.
- Remove dead plants immediately and dispose of them. Do not compost them. When removing the infected plants, keep as much of the root mass as possible. Infected roots left in the soil will result in higher amounts of Verticillium wilt.
- Use an organic fertilizer low in nitrogen and higher in potassium.
- Sterilize tools between each use, especially pruning tools.
Susceptible Trees
- Maple
- Box elder
- Tree-of - heaven
- Pecan
- Catalpa
- Carob
- Redbud
- Camphor tree
- Yellow wood
- Carrotwood
- Persimmon
- Oleaster
- Russian olive
- Weeping fig
- Indian laurel
- Ash
- Golden rain tree
- Tulip tree
- Southern magnolia
- Black gum
- Olive
- Avocado
- Chinese pistache
- Pistache
- Almond, apricot, cherry, peach,
- Black locust
- California pepper tree
- Brazilian pepper tree
- Elm
Susceptible Vegetables
- Peanut
- Horse radish
- Rutabaga
- Cabbage
- Brussels sprouts
- Pepper
- Safflower
- Hemp
- Watermelon, citron
- Cantaloupe
- Cucumber
- Pumpkin
- Strawberry
- Cotton
- Okra
- Tomato
- Mint
- Radish
- Rhubarb
- Castor bean
- Eggplant
- Potato
- Spinach
- New Zealand spinach
- SaIsify
- Yard-long bean
- Cowpea
Shrubs and Ornamentals
- Abutilon
- Snapdragon
- Udo
- American spikenard
- Aster
- BelIadonna
- Slipperwort
- Poppy-mallow
- China aster
- Bellflower
- Cockscomb
- Sweet sultan
- Marguerite
- Italian chrysanthemum
- Shasta daisy
- Chrysanthemum
- Clarkia
- Tickseed
- Dahlia
- Rocket larkspur
- Foxglove
- Cape marigold
- California poppy
- Transvaal daisy
- Strawflower
- Heliotrope
- Garden balsam
- Sweet pea
- Gayfeather
- Lobelia
- Stock
- Peony
- Oriental poppy
- Pelargonium
- Geranium
- Petunia
- Phlox
- Polemonium
- Pyrola
- Mignonette
- Black-eyed susan
- Painted tongue
- Mealy-cup sage
- Sage
- Blue sage
- Butterfly flower
For more information, see
Verticillium Wilt of Trees and Shrubs (UNM)
Tomatoes and Verticillium Wilt, (Cornell University)
