The spotted wilt virus in dahlias affects more than 200
species of vegetable and ornamental plants worldwide. The disease is spread
only by thrips.
Thrip larvae acquire the virus by feeding on host plants, like dahlias with
spotted wilt disease. When the thrips mature, their ability to fly spreads the
virus to healthy plants.
Symptoms of Dahlia Wilt Disease
Originally discovered in tomato plants, this viral disease
was aptly named the tomato
spotted wilt virus (TSWV). In tomato species, this virus causes wilting of
the leaves and yellow spots on the fruit.
The name of this disease can be deceptive, though, as
gardeners aren’t likely to find that their dahlias are wilting. The presence of
thrips on infected plants, coupled with common symptoms, is a better indicator
to suspect dahlia wilt disease. Due to their small size, thrips may be hard to
see. The trick is to tap the dahlia
over a piece of white paper or cloth. The thrips will appear as dark specks.
The most common symptoms of infection from the dahlia
spotted wilt virus include:
- Yellow spotting or mottling of leaves
- Necrotic ring spots or lines on leaves
- Malformed leaves
- Deformed or stunted growth of flowers and buds
- Flowers exhibit color breaking (have a streaked appearance)
- Plant loss (primarily of young dahlias)
Definitive diagnosis of the spotted wilt virus in dahlias is
difficult since the symptoms mimic other diseases and conditions, including
nutrient deficiency. Additionally, dahlias with spotted wilt may be
asymptomatic or show few signs of infections. The only true way to detect
dahlia spotted wilt virus is by testing tissue samples with an enzyme-linked
immunosorbent assay or ELISA test. Your local
extension office can help with this.
Controlling Spotted Wilt Virus in Dahlias
Like most viral diseases in plants, there is no cure for
dahlia wilt disease. The best course of action is to eliminate plants infected
with the dahlia spotted wilt virus.
Greenhouse operators and home gardeners can prevent further
spread of the dahlia spotted wilt virus by following these management
practices:
- In the greenhouse setting, use yellow sticky tapes to catch thrips and monitor their population levels.
- Implement a thrip larvae control program based on thrip population density.
- Screen greenhouse openings with fine mesh screening to prevent adult thrips from entering.
- Avoid growing garden vegetables and ornamental plants in the same greenhouse.
- Don’t propagate plants infected with the virus even if that portion of the plant looks healthy. (It can still harbor the virus.)
- Eliminate weeds that can serve as host plants.
- Promptly dispose of plants infected with dahlia wilt disease.
The spotted wilt virus in dahlias affects more than 200
species of vegetable and ornamental plants worldwide. The disease is spread
only by thrips.
Thrip larvae acquire the virus by feeding on host plants, like dahlias with
spotted wilt disease. When the thrips mature, their ability to fly spreads the
virus to healthy plants.
Symptoms of Dahlia Wilt Disease
Originally discovered in tomato plants, this viral disease
was aptly named the tomato
spotted wilt virus (TSWV). In tomato species, this virus causes wilting of
the leaves and yellow spots on the fruit.
The name of this disease can be deceptive, though, as
gardeners aren’t likely to find that their dahlias are wilting. The presence of
thrips on infected plants, coupled with common symptoms, is a better indicator
to suspect dahlia wilt disease. Due to their small size, thrips may be hard to
see. The trick is to tap the dahlia
over a piece of white paper or cloth. The thrips will appear as dark specks.
The most common symptoms of infection from the dahlia
spotted wilt virus include:
- Yellow spotting or mottling of leaves
- Necrotic ring spots or lines on leaves
- Malformed leaves
- Deformed or stunted growth of flowers and buds
- Flowers exhibit color breaking (have a streaked appearance)
- Plant loss (primarily of young dahlias)
Definitive diagnosis of the spotted wilt virus in dahlias is
difficult since the symptoms mimic other diseases and conditions, including
nutrient deficiency. Additionally, dahlias with spotted wilt may be
asymptomatic or show few signs of infections. The only true way to detect
dahlia spotted wilt virus is by testing tissue samples with an enzyme-linked
immunosorbent assay or ELISA test. Your local
extension office can help with this.
Controlling Spotted Wilt Virus in Dahlias
Like most viral diseases in plants, there is no cure for
dahlia wilt disease. The best course of action is to eliminate plants infected
with the dahlia spotted wilt virus.
Greenhouse operators and home gardeners can prevent further
spread of the dahlia spotted wilt virus by following these management
practices:
- In the greenhouse setting, use yellow sticky tapes to catch thrips and monitor their population levels.
- Implement a thrip larvae control program based on thrip population density.
- Screen greenhouse openings with fine mesh screening to prevent adult thrips from entering.
- Avoid growing garden vegetables and ornamental plants in the same greenhouse.
- Don’t propagate plants infected with the virus even if that portion of the plant looks healthy. (It can still harbor the virus.)
- Eliminate weeds that can serve as host plants.
- Promptly dispose of plants infected with dahlia wilt disease.