What Is Aster Yellows Virus?

By: Gary Antosh

Aster yellows is a plant disease caused by phytoplasm. It manifests like a virus, and sap-sucking insects spread it. 

The main vector of the disease is the Aster leafhopper. 

Plants with the Aster yellow virusPin
image by: Missouri Botanical Garden

These insects typically overwinter along the Gulf of Mexico and then migrate to the north during the spring and summer growing season.

More than two hundred different species of plants are affected by Aster yellows. 


Among them are:

This disease can affect some edible plants, such as:

There are also many types of weeds, grains, and grasses affected by the disease. 

Some of the main weeds to harbor Aster leafhoppers are dandelions and plantain, but many other broad-leafed weeds provide homes for these pests.

How Are Aster Yellows Spread?

Leafhoppers feed on a wide variety of plants, and when they feed on a plant already infected with Aster yellows, they carry the disease along to the next host. 

Environmental conditions somewhat mitigate the spread of the disease. 

During hot, dry weather, the phytoplasm is not spread much. 

It is uncertain whether these weather conditions are less conducive to the leafhoppers or the phytoplasm. 

Either way, the disease is more likely to be spread during cool, wet weather in the summer.

Apply food grade diatomaceous earth to the plants leaf surface or use a Neem oil spray.

What Damage Does Aster Yellows Cause?

There is no recovery from this disease. Once the plant is infected, it’s a goner! 

Symptoms will manifest within 10 to 40 days, and although the infected plant may continue to struggle along, it will never mature properly or produce seed.

One of the best ways to combat Aster yellows is to know how to diagnose the problem. 

Here are the types of damage you should look for in your plants:

  • Chlorosis: If the leaves of your plants turn yellow, but the veins stay green, this is a sign your plant has been infected with Aster yellows.
  • Stunted Growth: If the growth of your plant slows down and/or the leaves are smaller than they should be, suspect Aster yellows.
  • Deformed Leaves: If your plants’ leaves are curled, Aster yellows may be the culprit.
  • Deformed Flowers: The plants’ flowers may also be deformed, and you may find leaves growing where petals should be.
  • No Seeds: Your flowers may look fine, but they may not develop seeds.

If Aster yellows invade your vegetable garden, you’ll see different symptoms. 

For example, carrots may be bitter and have a hairy appearance. 

Lettuces may develop tan or pink spots on the leaves. 

They may also develop twisted leaves on the inside of the heads.

No matter what type of garden Aster yellows hits, the disease means failure for any plant. 

Even though individual plants may survive with the disease, they cannot develop fully, reach maturity, or attain their intended purpose. 

Every moment an infected plant is left standing presents an opportunity for other plants to become infected.

How To Control the Pest or Condition?

As with many types of plant pests and diseases, an Integrated Pest Management (IPM) strategy is your best bet for keeping Aster yellows under control. 

Here’s how:

Be Ruthless About Removing Diseased Plants 

There is absolutely no point in attempting to save a plant affected by Aster yellows. 

There is no cure for this disease, so it’s best to remove infected plants the moment you notice them. 

This can help reduce the spread of this incurable disease.

Choose Plants Less Susceptible to Aster Yellows 

It is very hard to get rid of Aster yellows, but there are some types of plants which naturally resist the disease. 

Among them are:

Keep Insects Under Control 

If there are leafhoppers in your garden, expect your plants to be infected by Aster yellows. 

Keep these pests away from your plants through several natural strategies, including:

  • Cover your vegetable crops with mesh fabric to keep the leafhoppers out.
  • Lay strips of aluminum between your rows of plants as it is believed leafhoppers are confused by shiny objects.

Keep Weeds Under Control 

Because Aster yellows negatively impact so many types of plants, chances are any weeds you have in your yard may harbor the leafhoppers which carry it. 

Be especially careful to remove dandelions and plantain.