Answer: It sounds like it may be some type of fungal disease. There is a fungus called Black Spot. Black spot thrives in humid, warm conditions. Sometimes it starts out with yellowing leaves. Check daily to see if more yellow leaves are appearing and if any have blackened areas. You can prevent black spot from returning by being very careful with watering practices, do not wet the foliage, but water the soil, do not water in the evening, water early in the day so no moisture accumulates long on the foliage. Also, to prevent fungal infections, make sure plants aren't crowded and have good air circulation and sunlight penetration. Clean up and destroy leaf drop and prunings, which causes reinfection. If you don't feel that these conditions exist, I suggest you take a sample of the problem to your County Cooperative Extension office for ID. They are at 209 S. St. Marie, Wautoma, 787-0416. Good luck!
Q&A Library Searching Tips