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Stunted growth on Cup plants in Community native and rain gardens #876170

Asked July 07, 2024, 7:45 AM EDT

Please help in identifying the cause of stunted growth and deformed leaves of cup plants in a large rain garden and native garden in Rust Park in Grand Blanc, Michigan. Possible virus or fungus? Also need assistance in identifying how to treat. Other native plants in the garden (ironweed, Japanese anemone and spiderwort) do not appear to be affected. I have been taking care of this garden for the last 10 years with cleanup of old plant stalks and debris each spring, monitoring in the summer months with occasional weed removal and cut back of some plants on the edge of the garden where turf is mowed by city maintenance workers. I also cut back most of plants (leaving some in the center uncut) in the fall to 3-4 ft height for overwintering. This oval shaped garden is located in a “depression” in the park that is sometimes flooded from large rainfall runoff usually in the spring. No herbicides are used in the garden.

Genesee County Michigan

Expert Response


Hello,

Stunted growth and deformed leaves in Cup Plants (Silphium perfoliatum) can result from various factors. The lower leaves can drop during periods of drought. The leaves and buds can turn brown, grow stunted and flowers may fall off in response to drought or disease. More information at this link:

Silphium perfoliatum (Common Cup-plant, Compass-plant, Cup-plant, Indian Cup) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)

Let’s explore some possibilities:

Pests: 

Aphids: These small, soft-bodied insects suck sap from leaves, causing curling, yellowing, and stunted growth. Red aphids are occasionally found on the underside of the leaves.

Treat with insecticidal soap or neem oil.

Spider Mites: Tiny arachnids that feed on sap, leading to yellow or brown spots on leaves. Use miticide or insecticidal soap.

Whiteflies: Flying insects that cause yellowing, stunted growth, and leaf drop. Treated similarly to aphids.

Diseases:

Root Rot: Fungal disease due to overwatering or poor drainage. Symptoms include yellowing leaves, wilting, and stunted growth.

Viral Infections or Aster Yellows: Entire plant removal may be necessary for control. More information at this link:

2101 – Abnormal & Distorted Plant Growth – PlantTalk Colorado (colostate.edu)

Remember to inspect your plants regularly, remove dead material, and consider natural predators like ladybugs or lacewings. opt for natural treatments when possible and treat every 7-10 days until pests are under control.

For a confirmed and precise identification of the problem, I recommend you send all your images by e-mail to the MSU Plant & Pest Diagnostics Lab. The experts there can also provide you with the best treatment options. Their email is <personal data hidden>. Please include your name. The lab will let you know if they need a sample sent. FYI, the lab may also ask for additional images.

Their website is at this link:

Plant & Pest Diagnostics (msu.edu)

Their Contact Information is at this link:

Contact Us - Plant & Pest Diagnostics (msu.edu)

This link will explain the details of submitting a sample to MSU Plant & Pest Diagnostics Lab:

Submit Samples - Plant & Pest Diagnostics (msu.edu)

I hope this helps!



An Ask Extension Expert Replied July 08, 2024, 9:15 AM EDT

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