I have several varieties of zinnias growing. Several spots may run together, killing the entire leaf. But now, some of those plants have ugly leaf like this. Numerous yellow or tan spots can develop across the leaf forming irregular dead areas. As the fungus takes hold, the plant’s leaves will turn yellow and fall off. Do you grow your zinnias mainly for cutting flowers? Asked August 8, 2015, 12:11 AM EDT. Leaf loss in this manner will cause the plant stress, meaning that it will fail to flower or fruit. Name: Lily (Zone 11) cornflower Nov 6, 2016 8:39 AM CST. Alternaria brassicola: Also impacts brassicas, causing brassica dark leaf spot. These include fungal leaf spot, powdery mildew (which looks like someone sprinkled flour over your plants) and blight. Viruses: Many virus diseases affect zinnias. Views: 5699, Replies: 9 » Jump to the end. Spray with recommended fungicides two or three times during the season. Fungal leaf spot will infect aspen and poplar trees. Some started indoors and some direct seeded. Zinnias are prone to two leaf diseases in the Northeast: powdery mildew and leaf spot fungus. Most common zinnia cultivars and Z. haageana are susceptible. 1. Leaf spot will also cause problems for strawberry plants. The spots have grown with the leaves and gotten slightly worse. Brown spots on zinnia leaf. I am planting zinnia from seed. Leaf Spot (fungus – Cercospora zinniae): Small, roundish spots with gray or whitish centers. Zinnias are susceptible to a variety of fungal diseases. After reaching 5 feet tall, they developed small brown spots on the leafs. Symptoms Spots begin on lower leaves as dull gray water-soaked areas on the leaf. Pests and Diseases forum: Zinnia leaf problem. Hi all , I have not come here for a long time. All are easier to prevent than to cure. I have attached pictures to this email. The Crystal and Star series are highly resistant while the Profusion series are moderately resistant. They are difficult to impossible to prevent, but here are some ideas for you. If untreated, the small white spots will grow, forming a root-like structure. Alternaria alternata: Causes leaf spots, blights, and rots on over 380 plant types. It's nice to have new home, new domain. Bacterial leaf spot will also infect some annual and perennial flowering plants including geraniums, zinnias, purple cone flowers and black-eyed Susan. Zinnias seem to me to be more susceptible to powdery mildew than any other plant I grow and the method I use to control that is to spray either a mixture of 1 teaspoon baking soda mixed in 1 quart of water, or a 50/50 mixture of fat free milk and water, every 5 to 7 days as needed if the plants are infected or every 7 to 10 days if no PM is seen but the weather conditions indicate it could be. Alternaria brassicae: Common problem for brassica crops, causes damping off in young plants & leaf spot in older ones. Moisture remaining on foliage is one of the main reasons zinnias … Ok. This saps the plants leaves of nutrition and also prevents photosynthesis. Can also cause respiratory issues in humans. If so, just ignore the mildew; it doesn't kill the plant and we strip the leaves off when we use zinnias in bouquets anyway.