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. Hereâs the interesting part: the symptoms of plant eaten by pests is similar to symptoms of plants attacked by pathogens. 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. Practice good cultural methods. To prevent it, be sure there is good air circulation around the plants, and that they are not too close together. 3. 1 to 2 weeks after your average last frost date. Join our mailing list to receive the latest updates from HGIC. The ideal soil temperature for zinnia seed germination is 70°â80°F. Therefore, it is best to always water near the base of the plants. Spray plants weekly with a copper fungicide following periods of leaf wetness to reduce disease incidence. Pick out slugs as soon as you notice them. As the spots become larger, they may develop dark concentric rings in the centers. Although most research proves that rabbits donât like Zinnias, they may still munch on the plant for the fun of it. Fungus grows best on damp foliage, so either water the plants with a dripper system or soaker hose, or if youâve installed an overhead sprinkler system, water in the morning. These spots become brown or dark gray and wither, leaving holes in the leaves. The best way to keep plants healthy is by taking preventative measures. If you see any of these signs, rabbits are definitely the ones feeding on your Zinnias. Copyright © 2020 Clemson UniversityClemson Cooperative Extension | 103 Barre Hall Clemson, SC 29634864-986-4310 | Contact UsHGIC@clemson.edu. Rather than depending exclusively on pesticides, proper culture (soil preparation, fertilizers, irrigation, mulch, optimum plant spacing, and adequate sunlight) is the better method for preventing insect and disease problems. About 20 species. You can also use the all-natural method that has proven effective for thousands of years. You can set traps for earwigs by placing shallow bowls of vegetable oil under the infested plant. If this document didn’t answer your questions, please contact HGIC at email@example.com or 1-888-656-9988. Check with your local Cooperative Extension Service for pest controls recommended for your area. That means you may wake up one day and discover that only the stem of your plant is left behind. Spray plants following rainy periods, as rainy conditions increase disease occurrence and spread. Moreover, they often leave behind some of their droppings when they are done snacking on the leaves. 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. Hi all , I have not come here for a long time. More. Zinnia Pests & Diseases. Bacterial Leaf Spot: Xanthomonas campestris pv. The fungus may persist in seeds for up to 7 years but for only 2 years in plant debris. More often than not, diseases and infections in zinnia plants happen mainly because of insects. Disease Prevention & Control: Most diseases may be prevented when zinnias are watered and cared for properly. Whiteflies are a common and destructive greenhouse pest. Japanese Beetles could be the insect that eats your Zinnias. Usually, they bore tiny holes into the Zinnias leaves and flowers. Additionally, they feed mostly at night. Spray with insecticides every few weeks to control sucking insects which spread the viruses. If you find a metallic green insect with cooper brown wings, feeding on your Zinnias, that is most likely a Japanese Beetle. Pour alcohol or soapy water over trapped earwigs to kill them. It is also possible to find two-colored and mottled varieties. zinniae). Powdery mildew, caterpillars (which some gardeners plant Zinnias to attract). When to start inside:4 to 6 weeks before your average last frost date. Integrated Pest Management Strategies. Alternaria blight is the most common and conspicuous. Follow label directions for mixing and use. Zinnias can be susceptible to fungal diseases, especially powdery mildew. 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. 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. Spray neem oil in the evening to avoid leaf burns during the day. Species . Nevertheless, it becomes heartbreaking when pests start to eat the leaves. This is crucial because it is necessary to identify what is attacking your Zinnias before trying to control it. smpatton Springdale, AR May 03, 2015. These plants make up dense, upright, branched bushes with oval, dark green leaves and large, single and double daisy-shaped solitary flowers. Table 1. Zinnia or Zinnia, a beautiful flower. 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. Always spray flowering ornamentals in the late evening. zinniae is the causal agent of bacterial leaf spot of zinnias, and the symptoms of infection are purplish spots that usually remain small, but they become angular in shape. Zinnias have few insect pests, but aphids, spider mites, and whiteflies may damage plants, especially during hot, dry weather. Space plants at the recommended distance so that they all have good airflow. Fungicide & Insecticide Products for Disease & Pest Control on Zinnias. Spindly Shoots; Foliage Are Yellowed, Curled By Virus Diseases Various diseases caused by viruses occasionally attack zinnias. Always spray flowering ornamentals in the late evening. Deer scat is different from rabbit droppings, so look for paw prints and scat to identify the pest. Cercospora leaf spots on foliage are typically reddish-purple, small, and round with light gray to almost white centers. As they feed, they inject the phytoplasma into the vascular system of the zinnia and cause the developing flowers to become deformed. See Table 1 for examples of brands and products. These include copper-based fungicides, horticultural oil with baking soda, sulfur, myclobutanil, propiconazole, tebuconazole, and thiophanate methyl. Transplant outdoors after last frost. Pests and diseases. Cause The fungus Alternaria zinniae has been reported on zinnia from Oregon and found many times on samples sent to the OSU Plant Clinic. Also, use electric copper barriers around your Zinnias to keep them away from your plant. Always spray plants in bloom during the late evening. Barbara H. Smith, HGIC Horticulture Extension Agent, Clemson UniversityJoey Williamson, PhD, HGIC Horticulture Extension Agent, Clemson University. Sometimes the spots are rectangular with a reddish-brown or purple color. Informational table showing disease name, symptoms, pathogen/cause, and management of Zinnia diseases. Caterpillars, mealybugs, and spider mites also cause problems. If overhead watering is used, irrigate during the early morning hours to allow the leaves to dry quickly in the morning sunlight. Zinnias dying? That way, it wonât be difficult to identify the pest eating your Zinnias. The center of these leaf spots may eventually tear, fall out, and leave behind holes in the leaves. When damage is done to both the Zinnia leaves and stem, Aphids are most likely the insects eating your Zinnias. Stem and Root Rot Stem and root rot diseases cause black, mushy growth, and often kill zinnias. Aphids and spider mites can be hosed off the plants with a strong stream of water. The flowers of zinnia they exist in all colors except blue. 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. Make sure not to compost them; otherwise, you run at a risk of infecting other susceptible plants with the pathogens. Zinnias grow best in full sun all day; however, they may be more prone to leaf spot diseases in partial shade. Name: Lily (Zone 11) cornflower Nov 6, 2016 8:39 AM CST. Serious infections cause the leaves to turn brown quickly and shrivel. Disease incidence is greater if plants are watered in the late afternoon or evening, thus causing the leaves to stay wet longer. The holes bores are usually visible enough to notice the damage done to the plant. Some may have distinct markings or blotches. The better fungicides to control Alternaria leaf spot are chlorothalonil, copper fungicides, and mancozeb. Also, destroy the attacked plant to prevent the aphids from spreading. Zinnias do not benefit from being planted early; wait for warmer weather. For example, an attack by bacteria is manifested by wet spots with yellow borders on the stem, blooms, and leaves of the Zinnias. Mosaic Virus. All recommendations are for South Carolina conditions and may not apply to other areas. Use natural predators such as parasitic wasps to keep away aphids from your Zinnias. However, if fungicides are required, there are several that are very effective. Thereâs 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. Zinnias make terrific cut flowers, and cutting the flowers encourages new blooms. Wild or domestic rabbits can also eat zinnia leaves, and like with deer, the damage occurs suddenly, often overnight. These zinnias have become infected with powdery mildew (Golovinomyces cichoracearum).Mary Ann Hansen, Virginia Polytechnic Institute & State University, Bugwood.org. All three di seases a re favo red by warm, wet or very humid weather, overhead sprinkling, excess shade, and crowding of plants. Bacterial leaf spot of zinnia (Xanthomonas campestris pv. The interesting fact is: itâs not difficult to identify them as the culprit because they are very greedy. Bacterial and fungal spots, powdery mildew, and bacterial wilt may affect zinnias. Can anyone tell me what is wrong with my zinnias? For centuries, zinnias have graced gardens and spread their glorious colors throughout flower beds and â¦ Follow label directions for mixing and use. Mark unread; Skip to new; Mark unread Print Skip to new. At the end of the growing season, remove all plant debris to reduce the carry-over of fungal disease inoculum (the pathogen responsible for the infection). How can you identify them? Stems of these annuals will deteriorate over the winter, and we do not have research weighing their value for insects over the winter. Destroy infected plant. 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