What are the common diseases in Schisandra chinensis cultivation?
The common diseases in Schisandra chinensis cultivation are root rot, leaf blight, powdery mildew, etc. When using pesticides for disease control, you must select pesticide varieties that are formally registered by the Pesticide Inspection Institute of the Ministry of Agriculture and permitted for use by the state, in order to prevent the adverse effects of pesticide phytotoxicity on the growth of Schisandra chinensis and the residual hazards of highly toxic pesticides.
1. Root rot
Symptoms: This disease generally occurs from May to August. At the beginning of the disease, the epidermis at the junction of the root and the ground turns black, and further the cortex rots and falls off, forming a ring shape, the leaves wilt, and the whole plant dies after a few days.
Causes: The causes are relatively complex. In early spring and late autumn, the day-night temperature difference at the ground surface changes drastically, and the tissues at the rhizome are tender with low disease resistance; the cortex is frozen and infected by fungi, or mechanical damage at the rhizome can also cause rot and disease. Waterlogged and poorly drained land and relatively heavy clay soil have severe incidence, and plants that are not robustly developed and have poor cane maturity have severe incidence.
Control methods:
(1) Choose high, dry, non-low-lying loam or sandy loam plots to cultivate Schisandra chinensis.
(2) Strengthen field management, balance fertilization, enhance tree vigor, and pay attention to drainage during the rainy season. Before freezing in autumn, mound soil around the roots or cover with straw to prevent frost damage to the rhizome, and at the same time prevent frost heaving in early spring.
(3) Minimize damage to roots and plants during production operations.
(4) In the early stage of the disease, choose 50% carbendazim WP 500-fold solution, or 77% Duoning WP 500-fold solution, etc. for root irrigation; in the early stage of the disease, apply continuously 2-3 times with an interval of 7-10 days.
2. Leaf blight
Symptoms: The disease occurs from late May to early July each year. When the disease occurs, the leaf tips or edges first dry up, then gradually expand to the entire leaf surface; the leaves dry up and fall off, and then the fruit shrinks, causing early fruit drop.
Causes: Humid air and relatively heavy rainfall conditions make it prone to occur. It is more severe in orchards with insufficient fertilizer or excessive nitrogen fertilizer, low-lying terrain, and a dense trellis canopy. After leaf fall or before budding, thoroughly clean up diseased branches and leaves, burn or bury them deeply to reduce the density of overwintering pathogenic bacteria. Before budding, spray the whole orchard once with 5 Baume degree lime sulfur mixture. In management, pay attention to the reasonable distribution of canes, avoid a dense trellis canopy, and enhance ventilation and light transmission.
3. Powdery mildew
Symptoms: Infection generally starts from young leaves first. Needle-like spots appear on the back of the leaves, gradually covered with white powder, and in severe cases spread to the entire leaf. Diseased leaves turn from green to yellow, curl upward, wither, and fall off. When young leaves are affected, it first spreads from near the ear axis to the entire fruit cluster; diseased fruits wilt and fall off, and dark brown spots appear on the fruit stalks and new shoots.
Disease conditions: The pathogen spores can germinate at 4-7°C, and the optimum germination temperature is 25-28°C. Under high temperature and drought conditions, it is favorable for the disease. Generally, the early stage of the disease is from late May to early June, and the peak stage is reached in late June. From the incidence of the plants, environmental conditions such as overly dense canes, excessive vegetative growth, excessive nitrogen fertilizer application, and poor ventilation are favorable for the occurrence of this disease.
Control methods: In the early stage of the disease, spray 25% Fenxiuning WP 2000-fold solution, 45% Daconing WP 800-1000-fold solution, 47% Jiaruinong WP 800-fold solution, 70% thiophanate-methyl WP 1000-fold solution, etc., spraying once every 7-10 days, for a total of 2-3 times.