Aster Yellows Returns

Several years ago I posted about our plants on our hill. In my little description of the coneflower (Echinacea purpurea) we have I mentioned that they got Aster Yellows that first year. I finally realized that I didn't have any pictures of a coneflower infested with the disease, which was a great over-sight on my part. Well, Aster Yellows has again raised its ugly head on our hill, and this time I have pictures.

As a recap, Aster Yellows is a virus that affects plants in the Asteracea family. The disease causes bizarre distortions in the flowers, sometimes preventing the petals from expanding, and the foliage to turn a funny yellowish color. It is spread by leaf hoppers and is untreatable. Infected plants aid in spreading the disease and will become worse in ensuing years. The only way to treat Aster Yellows is to remove the infected plants - even if that means all of them.

The Asteracea family is a very large family and includes both annuals and perennials. I wouldn't fret too much if an annual got Aster Yellows in Minnesota since it would be dead by October anyway; our greater concern is for our perennials. The more popular perennials in the Aster Family include:

Achillea (Yarrow)
Artemisia
Aster
Centaurea
Chrysanthemum
Coreopsis
Echinacea (coneflower)
Eupatorium (joe pye weed)
Gaillardia
Helenium (sneezeweed)
Heliopsis (false sunflower)
Leucanthemum (shasta daisy)
Liatris
Ligularia
Rudbeckia (black-eyed susan; does not show symptoms but is a carrier)
Solidago (goldenrod)
Tanacetum (painted daisy, feverfew)
Veronica (spike speedwell)

I have seen Aster, Echinacea, Liatris and Veronica infested with Aster Yellows.

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We have a display garden at work and we just had to remove all of the Echinacea. That prompted me to check on ours on the hill. Most of them still look good, but there was one volunteer that was terribly infected. The different stages and severity levels of the disease were showcased wonderfully.

Sometimes the cone is distorted and discolored. As you can see, the petals on the side most affected are also discolored and stunted.

Other times the flower doesn't bloom at all and is distorted until it hardly resembles a proper flower.

Then it progresses to something down-right alien.

After this plant's final photo op, it was promptly pulled up and thrown away. I've learned not to cry over removing the infected plants (but I will admit it was very hard to do so when we first planted the hill) now that I know the healthy plants will more than make up for the lost ones.