As they feed, they inject the phytoplasma into the vascular system of the zinnia and cause the developing flowers to become deformed. Insect Pest Prevention & Control: Zinnias are excellent sources of pollen and nectar for many beneficial insects; therefore, it is not recommended that insecticides, other than insecticidal soap, be used to control damaging mite and insect pests. Bacterial Leaf Spot: Xanthomonas campestris pv. Minimize wetting of foliage and space plants properly to avoid disease. Seed from infected plants can spread this leaf spot disease. Alternaria leaf spot of zinnia (Alternaria zinniae) starts as small, dark reddish, circular spots that rapidly expand and become irregularly shaped with grayish-white centers.John Hartman, University of Kentucky, Bugwood.org. See Table 1 for examples of brands and products with these fungicides and follow label directions for mixing and use. When to sow outside:RECOMMENDED. Also, destroy the attacked plant to prevent the aphids from spreading. More often than not, diseases and infections in zinnia plants happen mainly because of insects. Zinnia or Zinnia, a beautiful flower. Mark unread; Skip to new; Mark unread Print Skip to new. Zinnias grow best in full sun all day; however, they may be more prone to leaf spot diseases in partial shade. smpatton Springdale, AR May 03, 2015. Earwigs are easily identifiable with their long reddish-brown bodies with two short and sharp forceps. Gardeners Yards is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com, 6 Pests That Could Be Eating Your Zinnias. Pests and Diseases forum: Zinnia leaf problem. Zinnias dying? Pick out slugs as soon as you notice them. Can anyone tell me what is wrong with my zinnias? There’s nothing more beautiful than having a garden of healthily groomed Zinnias with gorgeous blossoms and green leaves.eval(ez_write_tag([[336,280],'gardenersyards_com-medrectangle-3','ezslot_6',107,'0','0'])); The sight is simply mind-blowing and exceedingly rewarding for its owner. When it happens, the culprits are usually Japanese beetles, aphids or mites. Nevertheless, it becomes heartbreaking when pests start to eat the leaves. Mosaic Virus. Zinnias (Zinnia elegans) are one of the most popular summer- and autumn-flowering plants. Informational table showing disease name, symptoms, pathogen/cause, and management of Zinnia diseases. Spindly Shoots; Foliage Are Yellowed, Curled By Virus Diseases Various diseases caused by viruses occasionally attack zinnias. Use natural predators such as parasitic wasps to keep away aphids from your Zinnias. Also, you will find the damage done to your leaves in the morning because slugs mainly feed when it is dark. COVID-19 Extension Updates and Resources ... More Information », Factsheet | HGIC 2110 | Published: Nov 9, 2020 | Print, Zinnias are excellent sources of pollen and nectar for many beneficial insects; therefore, it is not recommended that insecticides, other than insecticidal soap, be used to control damaging mite and insect pests.Barbara H. Smith, ©2019 HGIC, Clemson University. Moreover, they often leave behind some of their droppings when they are done snacking on the leaves. Always spray flowering ornamentals in the late evening. Bacterial and fungal spots, powdery mildew, and bacterial wilt may affect zinnias. zinniae). ALTERNARIA LEAF SPOT OR BLIGHT Name: Lily (Zone 11) cornflower Nov 6, 2016 8:39 AM CST. Views: 5748, Replies: 9 » Jump to the end. Don’t be surprised when they start feeding on them. The best way to keep plants healthy is by taking preventative measures. Infections occur not only on foliage but also on ray flowers, which will wither and produce lesions on stems, which often become girdled and finally wilt. Three common leaf spot diseases mar the b eauty of this be dding pla nt. For more information about the use of insecticidal soap, see HGIC 2771, Insecticidal Soaps for Garden Pest Control. The interesting fact is: it’s not difficult to identify them as the culprit because they are very greedy. Space plants at the recommended distance so that they all have good airflow. Stem and Root Rot Stem and root rot diseases cause black, mushy growth, and often kill zinnias. This will lessen or delay the occurrence of diseases the following year. Practice good cultural methods. Monitor for pests and diseases. Zinnias are rarely attacked by insects. This is the source of next season’s inoculum. Aster Yellows: Aster yellows is caused by a phytoplasma and is similar to a bacterium. They are usually spread by insects. Did you notice the damage done to the leaves during spring or summer? Diatomaceous earth tears the slugs apart as they crawl on it. To prevent fungal diseases, wet your plant only in the morning so the leaves can dry before nightfall.eval(ez_write_tag([[580,400],'gardenersyards_com-leader-1','ezslot_5',115,'0','0'])); Always pay close attention to your Zinnias so that you can detect as soon as pests start to eat your Zinnias. These sap-sucking insects love to suck the juice from the Zinnias plant by boring holes into the leaves and stems. Disease? However, if fungicides are required, there are several that are very effective. Do not use thiophanate methyl fungicides, as these are ineffective. Among the most prevalent are curly top, caused by curly top virus; mosaic, caused by the cucumber mosaic virus; and spotted wilt, cause by the tomato spotted wilt virus. Cercospora leaf spot (Cercospora zinnia) has light gray to white circular spots with reddish-purple borders.Barbara H. Smith, ©2019 HGIC, Clemson University. 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. Whiteflies also excrete honeydew, and it causes the leaves of your zinnia plant to turn yellow and die. Also, use electric copper barriers around your Zinnias to keep them away from your plant. I bought them and planted them about a week ago and they looked healthy. Clemson University Cooperative Extension Service offers its programs to people of all ages, regardless of race, color, gender, religion, national origin, disability, political beliefs, sexual orientation, gender identity, marital or family status and is an equal opportunity employer. Zinnia—Zinnia spp. There is no control method once the flowers have been infected, and plants with symptoms should be promptly removed and discarded in the trash. The colourful flowers attract bees, hoverflies and butterflies and you can choose from a range of white, yellow and orange to pink, purple, red and multi-coloured flowers. See Table 1 for examples of brands and products containing copper. See Table 1 for examples of insecticidal soap products. The holes bores are usually visible enough to notice the damage done to the plant. You can apply powdered fox urine or blood meal around the foliage to repel rabbits from the plant. Finally, rotate where you plant your zinnias (and all plants) each year so pests and diseases specific to that plant don't have a good chance to buildup in the soil over time. See Table 1 for examples of brands and products. A plant owner that merely notices the hole can quickly conclude that the holes were bored by an insect. More. These spots may coalesce (run together), and heavily infected leaves usually die. Prompt removal of any highly pest-infested or disease-infected plants will reduce pest and disease spread. Spray neem oil in the evening to avoid leaf burns during the day. This is the best strategy for avoiding powdery mildew. Moreover, they often bore holes into the flowers of the Zinnias. Table 1. Aster leafhoppers (Macrosteles quadrilineatus), may carry and transmit aster yellows, which is a plant disease caused by a phytoplasma that causes flower deformities.Barbara H. Smith, ©2019 HGIC, Clemson University. Mildew likes cool, wet conditions, so water during the day instead of at night. They ravage the foliage, remaining only skeleton-like leaves. These spots become brown or dark gray and wither, leaving holes in the leaves. Spots may develop a yellow halo. If you find a metallic green insect with cooper brown wings, feeding on your Zinnias, that is most likely a Japanese Beetle. Plants are 12-18 inches in height and extremely disease resistant. Copyright © 2020 Clemson UniversityClemson Cooperative Extension | 103 Barre Hall Clemson, SC 29634864-986-4310 | Contact UsHGIC@clemson.edu. Fortunately, aster yellows is not extremely common. You can treat the infestation with insecticide, but be careful of chemicals that do more harm than good. Cause The fungus Alternaria zinniae has been reported on zinnia from Oregon and found many times on samples sent to the OSU Plant Clinic. Transplant outdoors after last frost. Zinnia Zinnia angustifolia Zinnias are a very bright and cheery bunch of flowers and they make an ace inclusion in the vegetable garden. If you have Zinnias planted in your garden, both the leaves and flowers are susceptible to attack from Earwigs. Follow label directions for mixing and use. Zinnias with the disease lose their bottom leaves, and their upper leaves are covered with gray powder, which is the mycelium of the fungi growing on the plant. Zinnias can be susceptible to fungal diseases, especially powdery mildew. The plants may show curled, distorted, mottled foliage, they may be stunted or deformed, wilting, turning yellow and then dying. A white film develops on the leaves. Insecticidal soap sprays must be directed at the lower leaf surfaces where many pests feed. If you see any of these signs, rabbits are definitely the ones feeding on your Zinnias. Disease Prevention & Control: Most diseases may be prevented when zinnias are watered and cared for properly. Zinnias make terrific cut flowers, and cutting the flowers encourages new blooms. Disease incidence is greater if plants are watered in the late afternoon or evening, thus causing the leaves to stay wet longer. This method works because the female parasitic wasps use Aphids as hosts to lay their eggs. Finally, always use less toxic pesticides to minimize the harm done to your Zinnias and insects beneficial to your plant. Powdery Mildew: Powdery mildew is a fungal disease (Golovinomyces cichoracearum) that appears primarily on plant foliage but may also infect flowers and stems. Spray plants following rainy periods, as rainy conditions increase disease occurrence and spread. of Plant Pathology & Environmental Microbiology Archives, Bugwood.org. The ideal soil temperature for zinnia seed germination is 70°â€“80°F. All three di seases a re favo red by warm, wet or very humid weather, overhead sprinkling, excess shade, and crowding of plants. Some may have distinct markings or blotches. That way, it won’t be difficult to identify the pest eating your Zinnias. Hope this helps--I love zinnias also! Barbara H. Smith, HGIC Horticulture Extension Agent, Clemson UniversityJoey Williamson, PhD, HGIC Horticulture Extension Agent, Clemson University. Caterpillars, mealybugs, and spider mites also cause problems. Prune out diseased tissue and destroy it. Pests & Disease: The biggest pests of zinnias are powdery mildew disease and Japanese beetles. Pests and diseases on Zinnias Old zinnia plants are susceptible to fungal disease, although they will still bloom successfully if affected. Fungicide & Insecticide Products for Disease & Pest Control on Zinnias. Only two diseases are commonly troublesome on zinnias (Zinnia elegans), powdery mildew and Alternaria blight. The holes bores are usually visible enough to notice the damage done to the plant. Pests and Diseases Botrytis lesion on a begonia leaf. Plant owners that are not familiar with insect pests may be unable to identify the Japanese Beetle as the culprit. Try not to get the foliage wet when you water plants and make sure they are in full sun. However, zinnias often carry powdery mildew and other diseases. Alternaria blight is the most common and conspicuous. Pour diatomaceous earth on the soil near the Zinnias plant. Use pesticides only according to the directions on the label. 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