Aster Yellows - Plant Pest on the Plains: How you can get involved in this important research

Cluster of coneflowers with visible head and leaf distortion.

Aster yellows phytoplasma (AYP), best known as Aster Yellows disease or Onion Yellows disease, is commonly observed in purple coneflowers across South Dakota and other Great Plains states. Recent funding from the North Central IPM Center will allow South Dakota State University Extension Specialists to monitor and better model distribution of AYP in specialty and commodity crop production across the region.

Identification

Phytoplasmas are known for the distortion that they cause on most hosts. This can range from abnormal yellowing to proliferation of stems to underdevelopment of flowers and fruits. While coneflowers are the most reported host for AYP in South Dakota, the disease is also known to infect zinnias, blanket flowers, cosmos, lettuce, onions, potatoes, wheat, canola, and many other crops. AYP (and other phytoplasmas) are spread through leafhopper feeding which enable the pathogen to be spread long distances and introduced into many additional hosts.

Flowers and Vegetables

Figures 1 through 6 illustrate common Aster yellows phytoplasma symptoms in a variety of flowers and vegetables.

Figure 1. Distortion and underdevelopment of flowers, which is a typical symptom of Aster yellows phytoplasma in coneflowers. (Courtesy: Whitney Cranshaw, Colorado State University, Bugwood.org)

Blanket flowers with visible greening and distortion. — Figure 2. Greening and distortion of flowers and buds due to Aster yellows phytoplasma. (Courtesy: Whitney Cranshaw, Colorado State University, Bugwood.org)

Flowers with clustering of stems and excessive growth from nodes. — Figure 3. Witches broom (clustering of stems and excessive growth from nodes) that can be associated with phytoplasma symptoms. (Courtesy: Whitney Cranshaw, Colorado State University, Bugwood.org)

An infected onion and a healthy onion. — Figure 4. An infected onion (left) versus a healthy onion (right). It can be observed that the bloom head is distorted. (Courtesy: Lindsey du Toit, Washington State University, Bugwood.org)

Distorted lettuce head-with twisted leaves, poor vigor, and distorted stems. — Figure 5. A distorted lettuce head- it has twisted leaves, poor vigor, and distorted stems. (Courtesy: Whitney Cranshaw, Colorado State University, Bugwood.org)

Infected carrot and healthy carrots arranged to illustrate disease symptoms. — Figure 6. An infected carrot (far left) versus healthy carrots. (Courtesy: Whitney Cranshaw, Colorado State University, Bugwood.org)

Row Crops and Weeds

Figure 7 illustrates the progression of Aster yellows phytoplasma symptoms in a variety common row crops and weeds.

Chart illustrating symptom progression for Aster yellows phytoplasma in a. thaliana, barley, canola, dandelion, sow thistle, and wheat. For a detailed description, please call SDSU Extension at 605-688-4792.

Figure 7. Aster yellows phytoplasma in a variety of other row crops and common weeds. (Courtesy: Development of Aster Yellows on Crop and Noncrop Species from the Canadian Prairies; Berenice Romero et al.; CC BY-NC-ND 4.0)

How you can participate in this project!

Scouting of flowers and vegetables in your garden may show that you have aster yellows active in the landscape. We are on the hunt for these samples, especially those that are not in coneflowers! If you are unsure about symptoms, those can be sent to SDSU Extension staff (below) for identification.

Two coneflowers with distorted heads due to Aster yellows phytoplasma.

Sample Submission

How can you submit samples for AYP confirmation? If you suspect that you have AYP in your horticultural crops, field crops, or weeds in your yard, reach out to Maddi Shires, Cody Molnar, Nick Volesky, or the Plant Diagnostic Clinic. To access the free testing program, you must mention that you are submitting samples for the AYP in the Plains Grant.

Sample Collection

How do you collect samples? Submit stems and leaves from suspect plants. It is important to keep the samples cold before sending. The best way to store samples is by placing them in a large plastic bag with DRY paper towels. The bag can then be stored in a fridge until shipping. When shipping samples, use caution when utilizing USPS due to recent delays and risk of sample deterioration. Please avoid sending samples on Friday or just before holidays.

For more information on the AYP disease system, check out our in-depth article, Aster Yellows Phytoplasma.

Aster Yellows - Plant Pest on the Plains: How you can get involved in this important research

Identification

Flowers and Vegetables

Row Crops and Weeds

How you can participate in this project!

Sample Submission

Sample Collection

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