Knowledgebase
California poppy turning black #877095
Asked July 13, 2024, 2:10 PM EDT
Hi,
Someone whose native garden I help with in Phoenix, Oregon has California poppy that are turning dark purple or black. In the photos you can see a myriad of tiny black spots on the stems, with some of the leaves entirely black. The owner uses arborist wood chips on top of the soil and drip irrigation but doesn't directly irrigate the poppy, only her native plants. No other plants are affected except for maybe some lavender bushes which appear to show a similar problem. The photos are google's HEIC format. If you can't open them, I can try another format. Let me know what you think!
Jackson County Oregon
Expert Response
Black spots on California poppy leaves can be caused by several factors, including fungi, bacteria, and overwatering:
Downy mildew: A fungus that thrives in damp conditions and can leave a powdery residue on the leaf surface. Look for irregular black spots, especially on the undersides of leaves, that may be accompanied by a fuzzy or downy growth. If left unchecked, these small lesions can grow into larger blotches. To combat mildew, you can try increasing airflow or using a fungicide.
Bacterial leaf spot: A bacterium that prefers warm, wet conditions and can manifest as water-soaked spots that turn black over time and may have a slimy texture.
Overwatering: Yellow leaves and black spots can be signs of overwatering. The soil may also feel soggy.
