I believe I’m in zone 6 or 6a. I’m at spadina and st Clair in Toronto. The garden faces north and gets sun from ?? To ??
Clay soil that I had compost added at least once every spring and late summer. Stripped away pine mulch this spring. I have an irrigation system but the coneflowers are not getting a heavy spray. Last year they had a bad case of powdery mildew. Treated them with sulphur powder at the very end of the season. No sign of powdery mildew yet. Can I use sulphur as a prophylactic? But here is the problem now… I think some bug is nibbling on the leaves. Please see attached photo. Any idea what it might be? Do you have a treatment you would recommend? 40 parts water : 1 part soap spray? Please let me know your thoughts. Thanks! Suzanne
Coneflowers, Echinacea spp., are affected by a few insect pests, but in general not to a worrisome extent. Curled and yellowing leaves may be caused by aphids, whiteflies and leafhoppers. Insecticidal soaps can be used against these pests. Japanese beetles eat holes in the leaves, but leave the veins intact. It is worth knowing what Japanese beetles look like in case they have made their way into your garden. Here is a link that you may find useful: https://www.torontomastergardeners.ca/pest-alert-japanese-beetles/
Powdery mildew is a fungal disease affecting many ornamental plants. It is most prevalent when the humidity rises. Your best defense against it is to follow good cultural practices: make sure your coneflower gets enough sun and your plants are not overcrowded; water from overhead early in the day rather than in the afternoon or evening; tidy your garden of all plant residue in the autumn; look for newer plant varieties that are resistant to mildew. Your local large nursery could advise on the use of an appropriate commercial fungicide against powdery mildew. Sulfur can damage plant tissues if applied during conditions of high heat and humidity.