Cypress trees, while aesthetically pleasing, can cause significant harm, especially when infected by cypress rust. This disease is common in China and directly affects the health and yield of various fruit trees, including pears, apples, and hawthorns. Understanding the life cycle, symptoms, and control measures of these fungal infections is essential for effective management.
The pear rust fungus primarily infects cypress species such as Chinese cypress, European cypress, and dragon cypress, with the latter being most susceptible. The main host plants include pears, hawthorns, and other fruit-bearing trees. On the other hand, Yamada rust affects cypress varieties like Xinjiang cypress, Greek cypress, and others, and it spreads to apple, sand fruit, and jellyfish trees.
When pear rust infects a cypress tree, initial symptoms appear as pale yellow spots on needles, leaf bracts, or twigs, followed by slight swelling. From February to March of the following year, conical, reddish-brown spore horns emerge from the affected areas. These spores become gelatinous after rain and turn into orange-yellow, pliable masses when dry. In severe cases, this infection can lead to the death of branchlets.
Yamada rust causes the formation of 3–5 cm tumors on branchlets, starting as yellow, flat areas. By spring, the center of the tumor lifts, revealing a brownish, coronal spore horn. When wet, the spores swell into petal-like structures, releasing basidiospores that spread through the air. If left unchecked, this infection can kill young branches and weaken the tree.
In terms of disease cycles, pear rust overwinters in infected cypress tissue. Symptoms appear between October and December, with yellow spots appearing on the foliage. By the following spring, teliospores become visible, and winter spores mature after late March. When temperatures exceed 5°C and moisture is present, these spores germinate, producing basidiospores that infect fruit trees like pears. However, they cannot return to cypress unless new infections occur.
Yamada rust also overwinters on cypress, forming brown spore horns in late spring. These spores germinate during rainy periods, spreading via wind to host trees such as apple and pear. Once established, the fungus produces spores that return to cypress, continuing the infection cycle.
To manage these diseases, several strategies are recommended. First, proper cultivation practices should be maintained, including adequate watering and pruning. Second, infected branches should be removed and burned during winter to eliminate the source of infection. Third, fruit trees near cypress should be sprayed with protective fungicides during critical periods—such as bud break and early fruit development—to prevent spore spread. Options include Bordeaux mixture (160–200 times dilution) or 25% triadimefon at 1500 times dilution.
Additionally, spraying cypress trees with 0.3% sodium pentachlorophenol in mid-October to November helps reduce spore transmission. A mix of 0.3% pentachlorophenol sodium and lime sulfur can be particularly effective. In mid-March, applying 3–5 degree lime sulfur or 25% triadimefon at 1000 times dilution can suppress spore production and reduce the risk of future infections.
By implementing these control measures, growers can significantly reduce the impact of cypress rust on both ornamental and fruit-bearing trees, ensuring healthier orchards and landscapes.
Dome Cameras
Dome Cameras,Bus Hd Internal Camera,Car Hd Surveillance Camera,Vehicle Hd Internal Camera
Vsstech Co.,Ltd. , https://www.vsstechcctv.com