Common diseases and prevention methods of Coreopsis grandiflora

Common diseases of Coreopsis grandiflora: powdery mildew

Symptoms

Coreopsis is particularly susceptible to powdery mildew if it is exposed to rain in summer or if the soil contains bacteria. Powdery mildew is also the most common disease of Coreopsis macrophylla, with the highest occurrence frequency. It mostly harms leaves and petioles.

Prevention and treatment methods

Attention should be paid to ventilation and light transmission. Severely infested leaves can be cut off and burned. Apply more phosphorus and potassium fertilizers, and nitrogen fertilizers should be appropriate. 70% methyl thiophanate wettable powder 700-800 times diluted, 50% mancozeb 800-1000 times diluted, or 50% carbendazim wettable powder 500-1000 times diluted can be used for spraying.

Common diseases of Coreopsis large-flowered: black spot

Symptoms

Black spot disease is also known as brown spot disease. It happens all over the country. The leaves of infected plants turn brown and dry, the petals shrink, and the leaves, stems, and flowers can all be harmed by this disease. Small dark brown spots initially appear on the leaves, which soon expand into large regular spots with a diameter of 2 mm to 10 mm and a reddish brown color.

As the spots expand and increase in number, the entire leaf turns brown and dries up. The disease starts at the base of the petiole on the stem and develops longitudinally, becoming dark brown stripes. The symptoms of floral damage are similar to those of leaves, and the petals soon shrink and dry up. During the seedling stage, when the base of the stem is affected, dark brown ulcers with sunken centers are formed. The spots gradually surround the stem, causing the seedlings to show symptoms of damping-off disease.

Prevention and treatment methods

Seeds must be disinfected before sowing (use 1000 times diluted 50% carbendazim wettable powder to soak the seeds for 10 minutes). After autumn, diseased leaves, diseased stems, etc. are destroyed in batches to eliminate the source of infection for the next year. Save seeds from healthy, disease-free mother plants. Spray with 50% Zineb or 5000 times diluted Mancozeb. When spraying, pay special attention to spraying evenly on the back of the leaves.

Common diseases of Coreopsis grandiflora: rust

Symptoms

Rust disease harms leaves and stems, with leaves being the most serious. The leaves are covered with rust, which hinders the normal growth of the plant.

Prevention and treatment methods

You can spray with 2000 times diluted 50% carboxin emulsifiable concentrate. High temperature, high humidity and poor ventilation are prone to aphid pests, which harm leaves, tender stems, corollas, etc. You can spray 1000~1500 times diluted 40% Dimethoate Emulsifiable Concentrate.