Dahlia Verticillium Control: How To Treat Wilting Dahlia Plants

Dahlias are prized for their array of colors, flower size, and long-lasting blooms. So naturally when gardeners discover wilting dahlia plants in their gardens, concern is warranted. If watering doesn’t rejuvenate the affected plants, gardeners should consider dahlia verticillium wilt as the causative agent.

What is Dahlia Verticillium Wilt?

Verticillium wilt is an opportunistic, soil-borne fungal disease that infects many types of plants, including species of flowers, garden vegetables, and trees. It exists in the soil as mycelia, which is the vegetative part of the fungus comprised of branching, thread-like white filaments.

The fungus, Verticillium
dahliae
, infects the roots of plants where it plugs the water conducting
tissue. Even though the soil is moist, water can’t reach the leaves and the
plant exhibits signs of wilting. Dahlia plants affected by this fungus often
begin wilting on a single branch rather than the entire plant. The leaves on
that branch may turn yellow.

Eventually, the entire plant will be impacted. Upon closer
inspection, the vascular tissue in infected plant stems will appear dark brown
or black. Outbreaks are more common when warm temperatures follow cooler
weather

Dahlia Verticillium Control

Unfortunately, there is no cure once gardeners find
verticillium on dahlias. It’s best to remove and destroy plants infected with
dahlia verticillium wilt to prevent it from spreading.

A laboratory culture can confirm the diagnosis of
verticillium and there are methods for treating dahlia verticillium infected
soil. These include soil
fumigation
with chloropicrin-methyl bromide or metham-sodium. In sunny
locations, soil
solarization
has also been shown to be effective for treating dahlia
verticillium living in the soil.

Home gardeners may find agricultural management techniques a
suitable alternative for dahlia verticillium control. These include:

  • Whenever possible, select flower species that are resistant to the fungus. Plant dahlias in mixed beds with English daisies, cleome, or ageratum.
  • Plant dahlias under trees that are naturally resistant to verticillium. These include oak, dogwood, and willows.
  • Cut down infected shrubs or trees or prune branches exhibiting signs of dahlia verticillium wilt. Ash, maple, and elm are just a few species of trees that are susceptible to the fungus.

Lastly, consider growing
dahlias in pots
using pathogen-free or sterilized
potting soil
. Most varieties of dahlias are well suited for containers and
make a beautiful addition to patios and porches.

This article was last updated on 10/27/21
Read more about Dahlia Flowers

Dahlias are prized for their array of colors, flower size, and long-lasting blooms. So naturally when gardeners discover wilting dahlia plants in their gardens, concern is warranted. If watering doesn’t rejuvenate the affected plants, gardeners should consider dahlia verticillium wilt as the causative agent.

What is Dahlia Verticillium Wilt?

Verticillium wilt is an opportunistic, soil-borne fungal disease that infects many types of plants, including species of flowers, garden vegetables, and trees. It exists in the soil as mycelia, which is the vegetative part of the fungus comprised of branching, thread-like white filaments.

The fungus, Verticillium
dahliae
, infects the roots of plants where it plugs the water conducting
tissue. Even though the soil is moist, water can’t reach the leaves and the
plant exhibits signs of wilting. Dahlia plants affected by this fungus often
begin wilting on a single branch rather than the entire plant. The leaves on
that branch may turn yellow.

Eventually, the entire plant will be impacted. Upon closer
inspection, the vascular tissue in infected plant stems will appear dark brown
or black. Outbreaks are more common when warm temperatures follow cooler
weather

Dahlia Verticillium Control

Unfortunately, there is no cure once gardeners find
verticillium on dahlias. It’s best to remove and destroy plants infected with
dahlia verticillium wilt to prevent it from spreading.

A laboratory culture can confirm the diagnosis of
verticillium and there are methods for treating dahlia verticillium infected
soil. These include soil
fumigation
with chloropicrin-methyl bromide or metham-sodium. In sunny
locations, soil
solarization
has also been shown to be effective for treating dahlia
verticillium living in the soil.

Home gardeners may find agricultural management techniques a
suitable alternative for dahlia verticillium control. These include:

  • Whenever possible, select flower species that are resistant to the fungus. Plant dahlias in mixed beds with English daisies, cleome, or ageratum.
  • Plant dahlias under trees that are naturally resistant to verticillium. These include oak, dogwood, and willows.
  • Cut down infected shrubs or trees or prune branches exhibiting signs of dahlia verticillium wilt. Ash, maple, and elm are just a few species of trees that are susceptible to the fungus.

Lastly, consider growing
dahlias in pots
using pathogen-free or sterilized
potting soil
. Most varieties of dahlias are well suited for containers and
make a beautiful addition to patios and porches.

This article was last updated on 10/27/21
Read more about Dahlia Flowers
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