Lemon Diseases and Their Prevention

Lemon scab

Symptoms and occurrence

The disease mainly harms new shoots, young leaves, young fruits and leaves. The symptoms include funnel-shaped protrusions on the back of the leaves and sunken leaf surfaces. In severe cases, the leaves become deformed, the treetops become shorter, and the fruits have many tumor-like protrusions. The disease is caused by fungi and is spread by wind, rain and insects. Rainy and humid weather is an important condition for the onset of the disease.

Prevention and treatment methods

①Prune regularly and remove diseased leaves and branches. ② Spray the medicine 2-3 times each time the shoot grows 1-2 cm and when the flowers fall. Usually use 600-800 times of 70% thiophanate or 600-800 times of 50% carbendazim.

Lemon canker

Symptoms and occurrence

This disease mainly harms branches, leaves and fruits. The diseased leaves initially develop yellow, oily pinhole-like spots, which gradually expand into circular spots. The spots on both sides of the leaves become raised, the middle part becomes sunken and cracked, and appears gray-brown and rotten, with a yellow halo around it. When infected with the disease, the leaves do not become deformed but often fall off early, and the lesions on the fruits and branches are similar to those on the leaves. The disease is caused by bacteria and spread by rain and insects. High temperature, humidity, typhoons and rainy days can easily lead to illness.

Prevention and treatment methods

① Pay attention to quarantine to prevent the introduction of diseased seedlings and fruits. ② Spray medicine. When the new shoots grow to 4-5 cm, spray with 600-800PPm of streptomycin, 1000-1200 times of Copper Master, and 1200-1500 times of Shigao, which can kill 600-800 times.

Lemon sooty mold

Symptoms and occurrence

Lemon sooty mold harms leaves, branches, and fruits. When the disease occurs, a thin layer of dark brown mildew appears on the surface at first, which then spreads and even connects to form hair-like protrusions and a black film-like mildew layer. The sooty layer on the diseased leaves is easy to peel off, and sometimes there are small black spots. The pathogen uses the honey dew secreted by whiteflies, scale insects, aphids, etc. as nutrients. In addition to affecting photosynthesis, it also secretes toxins that cause plant growth to weaken and fruit quality to decline.

Prevention and treatment methods

① Strengthen pest control. When pests occur, spray 800-1000 times of cypermethrin or 600-800 times of whitefly killer. ②At the beginning of the disease, use 2500-4000 times of Xinsheng. ③ Strengthen management and prune branches reasonably to facilitate ventilation.