Hongye is famous for its ornamental value. In Beijing, Henan, Hebei and other regions, powdery mildew seriously affects the benign development of red leaves. It is necessary to use pesticides even if it is controlled, understand the symptoms of the symptoms and the disease, and better control method: Outdoor Red-crowned Crane Landscape Lights,Outdoor Red-crowned Crane Lawn Lights,Red-crowned Crane Landscape Lights,Simulation Red-crowned Crane Lights Sichuan Kangruntengpu Photoelectric Technology Co., Ltd. , https://www.tengpulighting.com
Symptoms Powdery mildew mainly harms the leaves. In the early stage of the disease, white needle-like spots are produced on the susceptible leaves, which gradually enlarge to form near-round spots. The lesions are radially surrounding, and the lesions are connected into pieces in the late stage, and the leaves are covered with white powder. The leaf tissue damaged by powdery mildew is chlorotic, affecting the photosynthesis of the leaves, causing the leaves to dry up and down. On the autumn leaves, yellow to yellowish brown gradually formed, and finally dark brown particles, which are closed capsules of pathogenic bacteria.
Pathogenesis of the pathogens overwintering on the leaves or on the branches of the closed capsules, and it is also possible to overwinter in the buds in the form of hyphae. In the early summer of the next year, the closed capsules are hydrolyzed and cracked to release ascospores. The mycelium directly produces conidia for initial infection, and the conidia are re-infected during the growing season. Generally, the rains in May and June are early, and the incidence is also early, and vice versa. The amount of rainfall in July and August determines the severity of the disease in the same year. The powdery mildew of Astragalus membranaceus begins to develop from the lower leaves of the plant and then gradually spreads upward. From the early stage of the disease to the beginning of August, the disease progressed slowly. From mid-August to mid-September, the disease developed rapidly.
Astragalus powdery mildew occurs from the bottom up. The lesion first appeared on the leaves of the branches below 1 m and then gradually spread to the canopy. The roots of Astragalus membranaceus tend to have many tillers, many young tissues, and the lower leaves are closest to the overwintering bacteria. The density of plants is high, and the incidence of poor ventilation is heavy; the trees growing on the top of the mountain are lighter than the trees growing in the valleys of the windy wind; the growth of jaundice is serious; the tree with more tillers is heavier.
Control measures 1 reduce the source of infection. In the autumn, combined with the Qingyuan, the diseased leaves were thoroughly removed, the dead branches were cut off and burned; the ground was sprayed with sulfur powder to eliminate the wintering pathogens. Strengthen water and fertilizer management to improve the tree potential and enhance disease resistance; in spring, cut off tillers in time to reduce the incidence of the disease.
2 chemical control: Astragalus sprayed Baume 5 degree stone sulfur mixture to kill the overwintering bacteria source. In the early stage of the disease, spraying 15% of the wettable powder rusting 800 times liquid can effectively control the occurrence of diseases , or use whitening, this agent is efficient, safe and does not produce resistance to pests.