What are the control methods for chrysanthemum foliar nematode disease?
Chrysanthemum foliar nematode disease is one of the important diseases of chrysanthemums. It is distributed all over the world, and occurs in Shanghai, Nanjing, Hefei, Guangzhou, Changsha, Kunming, Zhejiang and other places in China. It mainly damages chrysanthemum leaves, causing the leaves to turn yellow and drop early. Besides chrysanthemums, this nematode also harms China aster, black-eyed Susan, dahlia, ...
Chrysanthemum foliar nematode disease is one of the important diseases of chrysanthemums. It is distributed all over the world, and occurs in Shanghai, Nanjing, Hefei, Guangzhou, Changsha, Kunming, Zhejiang and other places in China. It mainly damages chrysanthemum leaves, causing the leaves to turn yellow and drop early. Besides chrysanthemums, this nematode also harms many plants of the Asteraceae family such as China aster, black-eyed Susan, dahlia and zinnia, as well as ornamental flowers such as Chloranthus, lily, calceolaria, larkspur and oleander.
Symptoms: This nematode mainly damages leaves, and can also infect flower buds and flowers. Generally, the lower leaves of the plant are affected first. On leaves infected by the nematode, the invasion point quickly turns brown. Afterwards, the brown spots gradually expand and, restricted by the leaf veins, form angular or irregular brown lesions. Finally, the leaves curl, wilt and droop, causing a large amount of leaf drop. After the floral organs are infected, the flowers do not develop, and even if they bloom, they grow small and deformed. Flower buds and flower buds dry up or degenerate, and some flower buds swell but fail to form buds. Severely affected plants wither and die before flowering.
Pathogen: The pathogen is the chrysanthemum foliar nematode (Apholonchoides ritsomabsi), belonging to the genus Aphelenchoides.
Disease pattern: The pathogenic nematode overwinters on diseased plants, diseased residues and wild hosts such as corn salad, chickweed and larkspur, and is generally spread through rainwater and irrigation water, penetrating into the tissue through leaf stomata to cause damage. The entire developmental cycle is completed within the damaged tissue. As long as temperature and humidity are suitable, the nematode can reproduce throughout the year.
Control: (1) Strengthen quarantine to prevent diseased seedlings, diseased plants and their propagation materials from entering disease-free areas. (2) Select healthy, disease-free cuttings as propagation material. Because the foliar nematode does not attack the terminal buds of the stem, terminal buds can be used as propagation material. (3) Gardening tools that have come into contact with diseased seedlings and diseased soil should be disinfected promptly. Soil and flower pots that have been used to grow diseased plants should be disinfected. (4) When cultivating in the open field, prevent water from splashing, and promptly pull up and burn diseased plants to reduce the chance of spread. (5) Apply 3% carbofuran granules in holes, 45-75 kg per hectare, which has a certain curative effect.