Have you noticed strange growths or damage on your coneflowers? Mine are looking very strange, so I did some research. It could be a sign of Aster Yellow Disease or an infestation of Eriophyid Mites. Let's dive into how to differentiate between the two and what you can do to protect your beloved plants.
What is Aster Yellow Disease?
I've been gardening for a long time and, I have to admit, I didn't know this was a thing. Aster Yellows is a plant disease caused by a phytoplasma bacterium which is spread to the plant by aster leaf hoppers when they feed on the plants. It affects a wide range of plants, including asters, marigolds, and tomatoes, but most often noticed on coneflowers.
Symptoms include yellowing of leaves, spoon shaped petals, stunted growth, and abnormal flower development. The head of the coneflower may be distorted and show leafy green growth on the cone of the flower.
Are Eriophyid Mites the Culprit?
Bugs are always an issue in the garden-both good and bad. These guys are bad. Eriophyid Mites, or commonly called Rosette Mites, are tiny arachnids that can cause damage to plants by feeding on their sap. These mites are so small that they are often invisible to the naked eye. Symptoms of Eriophyid Mite infestation include distorted leaves, stunted growth, and a silver or bronze discoloration on the leaves.
How to Tell the Difference
One way to differentiate between Aster Yellow Disease and Eriophyid Mites is to closely examine the affected plant. If you notice tiny, spider-like creatures moving around, chances are you're dealing with Eriophyid Mites. With mites, the cone is misshaped with odd growth but not typically green. On the other hand, if you see no visible pests, there is green growth coming from the cone, and the plant shows signs of phytoplasma infection, it's likely Aster Yellow Disease.
Protecting Your Plants
To protect your plants from Aster Yellow Disease, remove and destroy any infected plants to prevent the spread of the disease. For Eriophyid Mites, clip off the infected flowers and/or consider using insecticidal soap or neem oil to control the infestation. Regularly inspecting your plants for any signs of disease or pests can help you catch the problem early and take action promptly.
Remember, a healthy garden starts with vigilant care and attention. By knowing how to spot the difference between Aster Yellow Disease and Eriophyid Mites, you can better protect your plants and keep your garden thriving.
There are several sites to reference to decide if your plants have mites or Aster Yellows. Here are a few for you to do a deeper dive:
Piedmont Master Gardeners: Aster Yellows