Persian powder is an example of industrial product of chrysanthemum insecticide. Apply a foliar spray of chlorothalonil or thiophanate methyl. These fungi overwinter as spores in such debris. At 20 krad, no damage was noted and blossoming was prolonged. They need regular watering because their roots are very shallow. Be sure to apply the spray to all leaf surfaces. They tend to be more of a problem during hot, dry periods. Early damage is often overlooked until damage is more severe. The adult female lays eggs on the undersurfaces of leaves. If you want to check for these insects that can distort and damage foliage and plant vigor, place a piece of white paper under the plant. Early infection may cause blasting of the buds. Nematodes are slender, unsegmented roundworms that are barely visible to the unaided eye. Destroying any infected plant material may be necessary to prevent the spread of these diseases such as in the case of rust, wilt, and leaf spot diseases. Set new plants farther apart and provide better ventilation. Find more gardening information on Gardening Know How: Keep up to date with all that's happening in and around the garden. See Table 1 for examples of brands and products. This disease may be confused with Ray Blight disease. Earwigs shred foliage and leaf miners leave their characteristic trails under the foliage. These cheery flowers are rugged rays of sunshine, bestowing happiness just as winter’s icy fingers begin to chase away the summer. They can also spread viruses. One of the most beloved fall classics are chrysanthemums. These fungi cause brown or white necrotic specks surrounded by colored halos on the fully expanded ray florets when humidity and temperatures are high. This disease is caused by the fungus Mycosphaerella ligulicola. Gamma radiation was tested in Taiwan for the control of major insect pests on cut chrysanthemum flowers for export. Infected plants are stunted, form dense “rosettes”, and have small flowers. Issues affecting chrysanthemums can be diminished by proper cultivation, site location, and choosing disease resistant specimens. Follow all directions, precautions and restrictions that are listed. The leaves are covered with a whitish, ash-gray powdery growth. Leaves show brown water-soaked spots. Prevention & Treatment: Hand pick and destroy the infected leaves. Buy rooted cuttings, which are certified to be disease-free. Leaves may wither prematurely. Symptoms consist of spots on the leaves. Chrysanthemum aphids (Macrosiphoniella sanborni) and other aphid species are pests on chrysanthemums. They have piercing mouthparts with which they puncture plant tissue and suck plant sap. Sign up to get all the latest gardening tips! The fungus is soil-borne, and enters the plant through the roots, later invading the vessels of the stem and cutting off the water supply. Rust infection causes pale areas to appear on upper leaf surfaces, with powdery orange pustules or spots directly beneath on the undersides of the leaves. The following diseases all leave the evidentiary signs on foliage, stems, and blooms: There are numerous anti-fungal sprays that are effective among these diseases, with cultural controls such as ceasing overhead watering and changing the soil being additional safeguards. By: Bonnie L. Grant, Certified Urban Agriculturist. Infected parts become covered with a grayish-brown, powdery mass of spores. See Table 1 for examples of brands and products. Control: Prune off and destroy infested leaves. However, the mum plant diseases can encompass both bacterial and fungal and are more rampant problems. Disease, Insect Pest & Mite Control on Chrysanthemums. Dots of black waste products are visible in some of the trails. It is best to use resistant varieties. If this document didn’t answer your questions, please contact HGIC at or 1-888-656-9988. Feed these bloomers in spring and they will reward you with a fall display of color. Two-Spotted Spider Mites (Tetranychus urtica) and other mite species are pests of chrysanthemums. Table 1. Also, regularly clean up and destroy dead plant debris in the garden to reduce spore populations. Small black fruiting bodies may be seen in the lesions of some leaf spot fungi. See Table 1 for examples of brands and products. Water the soil without wetting the plants. The most pronounced symptom is a rot of the upper part of the stem, resulting in wilt and collapse of the distal portion. Nematodes can become dormant and survive for over a year in fallen leaves. This disease is caused by the fungus Botrytis cinerea. Pyrethrum was a genus of several Old World plants now classified as Chrysanthemum or Tanacetum (e.g., C. coccineum) which are cultivated as ornamentals for their showy flower heads. Most mums are extremely vigorous and have few pests and disease problems but there are a few issues affecting chrysanthemums of which growers should be aware. Remove and destroy them. Use pesticides only according to the directions on the label. Mites are extremely small and can barely be seen without a magnifying lens. A layer of helps prevent spores from splashing from the soil onto plants. This disease is caused by Erwinia chrysanthemi. Aphids are soft bodied, sucking insects that daub their sticky honeydew secretion across leaves and flowers. In addition to damage caused by their feeding, chrysanthemum aphids can transmit various plant viruses. Foliar sprays with insecticidal soap may help reduce nematode populations. Repeat as needed, but at least 3 times. Symptoms first appear as yellow spots which turn brown to black. Remove and destroy all infected plant material. Join our mailing list to receive the latest updates from HGIC. Remove and destroy any plant remains in the fall. Virus diseases are spread by sucking insects such as aphids and leafhoppers. They additionally infest hosta and ferns. Excess moisture is one of the main threats but so, too, are insects on mums who chew and suck, diminishing plant vitality. If natural predators do not keep aphids under control and serious damage is occurring, spray with one of the following materials: insecticidal soap, horticultural oil, acephate, malathion, cyfluthrin, permethrin, or bifenthrin. Infected cuttings may show a brown to black decay at their bases. Do not wound the stems. All recommendations are for South Carolina conditions and may not apply to other areas. All mums contain this substance, but the highest concentration level is found in Chrysanthemum coccineum, or painted daisies. At doses of >100 krad, treatment caused the leaves to blight after a week. With a hand lens white masses of spores may be seen on the leaf spots. Signs are usually stunted growth and yellowed foliage. These spots are at first yellowish, and then become dark brown and black, increasing from ⅛ to 1 inch or more in diameter.