High-Efficiency New Technology for Cultivating Mulberry and Raising Silkworms

Author: He Shaoyu
Publisher:
Publish Date: 2001-04-01
Features: Chapter 4 Common Pests and Diseases of Mulberry and Their Control
There are dozens of pests and diseases that can harm mulberry trees, causing varying degrees of damage. They not only directly affect the yield and quality of mulberry leaves but also promote the spread of the four major silkworm diseases (viral, bacterial, fungal, and microsporidian diseases), impacting the growth and development of silkworms and directly or indirectly reducing the yield and quality of silk cocoons. Therefore, silkworm farmers have summarized: "Many pests and diseases on mulberry trees lead to many sick silkworms in the rearing house." This illustrates the importance of controlling pests and diseases on mulberry trees. Although the harm caused by pests and diseases on mulberry trees is significant, as long as we attach great importance to it and implement the principle of "prevention first, comprehensive control," based on their occurrence patterns, we can take corresponding control measures to prevent and control pests and diseases, ensuring high-quality and high-yield mulberry leaves.
Diseases of Mulberry Trees
1. Mulberry Shrinkage Disease
Mulberry shrinkage disease mainly includes three types: flower-and-leaf type shrinkage, shrinkage type shrinkage, and yellowing type shrinkage. The flower-and-leaf type is caused by a virus, while the shrinkage and yellowing types are caused by a combination of viruses and viroids. Mulberry shrinkage disease poses a significant threat to mulberry cultivation and directly affects silk production.
1. Symptoms
(1) Flower-and-leaf type: Leaves are wrinkled and rolled upwards, with mottled patterns between lateral veins. The fine veins in the discolored spots turn brown, and warty and spiny protrusions often appear on the main veins or lateral veins on the underside of the leaves. Diseased branches bear flower catkins.
(2) Shrinkage type: Leaves become smaller and slightly yellow. In split-leaf varieties, diseased leaves often turn round, sometimes with half of the leaf rounded while the other half remains normal. The fine veins are often entirely brown. Leaves harden early, and branches and leaves grow densely and become stunted. Leaves are not very wrinkled, and there are no warty protrusions on the underside of the leaves. Diseased branches do not bear flower catkins. In severe cases, roots turn black, and fine roots rot.
(3) Yellowing type: Leaves turn significantly yellow, and the tips curl downward. There are no warty protrusions on the underside of the leaves. Leaves are slightly wrinkled, branches and leaves grow densely, and stunting is particularly severe. Diseased plants, if summer-pruned, often produce very small lateral branches and leaves, clustering together and dying within 2–3 years. Diseased branches do not bear flower catkins.
2. Disease Occurrence Patterns
All three types of shrinkage diseases overwinter in diseased plants as viruses. The shrinkage and yellowing types are transmitted through the jassidae and diseased shoot grafting, while the flower-and-leaf type is transmitted through diseased shoot grafting. The occurrence of the disease is closely related to climate, variety, fertilization, and management. The symptoms of the flower-and-leaf type shrinkage disease often do not appear when temperatures reach above 30°C, resulting in segments of diseased and healthy leaves on the same branch. The symptoms of the shrinkage type shrinkage disease become more apparent during summer pruning and when temperatures are high.
3. Control Methods
(1) Strengthen quarantine. Conduct thorough inspections and tests on seedlings and scions from diseased areas to prevent the transport of diseased seedlings and scions to healthy areas. Healthy areas are best to rely on self-propagation and cultivation.
(2) Remove diseased plants. When a few diseased plants are found in new diseased areas, they should be promptly removed to eliminate the pathogen and prevent the spread of the disease.
(3) Choose high-yield and disease-resistant varieties. Mulberry No. 7 is highly resistant to all three types of shrinkage diseases; Lotus Leaf Mulberry, Tongxiang Qing, and Mulberry No. 197 are highly resistant to the shrinkage type shrinkage disease; and Mulberry No. 199 is highly resistant to the yellowing type shrinkage disease.
(4) Prune diseased branches in lightly affected mulberry plantations and implement spring pruning, along with enhanced fertilization and management.
(5) Control pests to prevent disease. The shrinkage and yellowing types of shrinkage diseases are transmitted by jassidae. Therefore, it is necessary to control pests based on the occurrence patterns of jassidae to prevent disease. Use 50%