hi so I have a garden with zinnias. Powdery mildew affects the plant and takes away its nutrients. Know how to protect your watermelon plat from pests and diseases. Some may have distinct markings or blotches. Mosaic Virus. 4 / 10. deyanarobova/Getty Images. We can consult a local licensed professional for proper control of rice pests and diseases. Flowers are spotted and at times completely b Three major, widespread diseases occurring on zinnias are: Alternaria blight (Alternaria zinniae), powdery mildew (Golovinomyces cichoracearum, formerly Erysiphe cichoracearum), and bacterial leaf spot (Xanthomonas campestris pv. Flower colors vary and include white, orange, yellow, pink, red, purple, and gold. The zinnias have grown huge and have bloomed really well. Along with diseases, pests can also cause problems. Zinnia elegans. They are wonderful predator bugs. Zinnias are either annual or perennial plants with colorful round flowers. It is important to know our crop enemies and form an environmentally friendly approach in order to tackle them. There are two diseases to look for, too, in zinnias, which are powdery mildew and alternaria blotch. Alternatively, buy lady bugs and release them into your zinnia garden. Bacteria Wilt (bacterium – Pseudomonas solanacearum): This bacterium has been shown to cause a wilt of zinnias in Florida.. Blight (fungus – Alternaria zinniae): Small, reddish-brown spots with grayish centers are the first symptoms of this widespread and highly troublesome disease.Dark brown cankers also occur on the stems. Zinnia—Zinnia spp. I used miracle grow soil. However in the past few weeks a lot of the zinnias have gotten holes in the leaves, the leaves have turned brown and shriveled up, and … zinniae). These soft-bodied pests suck the plant juices from zinnias through holes they bore into the leaves and stems. More often than not, diseases and infections in zinnia plants happen mainly because of insects. Every year, more than one-third of rice crop production is lost to pests and diseases. Zinnia Flower: Pests and Diseases. The most common rice pests and diseases are listed below. Look for aphids on the underside of the leaves or on the stems just below the buds. Try washing them off with a powerful hose stream. Diseases often reduce the quantity and quality of zinnia flowers, causing their production to be unprofitable. Diseases are common and can prevent watermelon quality and supply. Problem: There are a number of mosaic viruses, but gardeners are most likely to encounter two: tomato mosaic virus and tobacco mosaic virus. Family Asteraceae (Sunflower family) Plant Identification.