ROS under/overwatering or fungus?
Hi all, Hope someone can help. Have 3 ROS, all purple Althea(?)double flower, planted 20 ft away from each other. Had the same problem last yr. w/ same plant, so this yr gave all 3 a systemic insecticide a month ago. The problem has come back - no insects, but most leaves on one are developing black edges, and some are turning yellow. Other 2 are fine. Basically, all get equal treatment with regard to watering, sunlight, fertilization, and insect control. Two are fine, but I'm at my wits end, as I'm expecting early (yellowed) leaf drop and few if any flowers on this one (even though many buds). Any takers? Thanks! Kathy