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Occurrence and control of black spot of Impatiens balsamina

Published: 2024-11-05 Author: mysheen
Last Updated: 2024/11/05, The black spot of Impatiens balsamina is an important disease in the production and cultivation of Impatiens balsamina. It occurs widely in China and causes serious damage. Symptoms of the disease damage leaves, especially in the lower part of the old leaves easy to infect the disease, the affected leaves appear round or oval spots, dark brown, 2 - 10 mm in diameter, with inconspicuous ring patterns, dark edge color. When the disease occurs seriously, the spots can be expanded to connect with patches, and there are light green or black mildew on the spots, that is, conidia and conidia of the pathogen. causing the diseased leaves to shrivel and die.

Black spot of Impatiens balsamina is an important disease in the production and cultivation of Impatiens balsamina. It is common and harmful in China, which should be paid attention to.

Symptoms of the disease damage leaves, especially the middle and lower parts of the old leaves are prone to infection, the damaged leaves appear round or oval disease spots, dark brown, 2Mel 10 mm in diameter, there are not obvious wheel lines, the edge is dark. In severe cases, the disease spot can expand and connect the plaque, and there are light green or olive-black mildew on the spot, that is, the conidiophores and conidia of the pathogen. It causes the diseased leaves to shrink and die.

Pathogen AlternariatenuisNees. It belongs to the subphylum of semi-knowns and Alternaria fungi. Conidiophores erect, brown, flexion, apical disease often enlarged with spore scars, size 5-125um × 3-6um. Beaked, dark brown, size 1-58.5um × 1.5-7.5 um, 1-9 transverse septum, 0-6 mediastinum.

The pathogen overwintered with mycelium on the remnant of the diseased plant and produced conidia for primary infection and re-infection when the conditions were suitable in the spring of the following year. Generally spread by airflow, like high humid environment, rainy, re-dew is conducive to the disease and epidemic. The peak period of the disease is from July to August in Northeast China, and it decreases gradually in the first and middle of September.

Prevention and cure method

The main results are as follows: (1) Agricultural control should strengthen cultivation management, fertilize and irrigate reasonably, maintain proper ventilation and improve plant disease resistance. Timely drainage after rain, removal of diseased bodies, removal of lower old leaves, diseased leaves. It is concentrated and buried or burned to reduce the amount of overwintering bacteria and improve the soil.

(2) to implement the rotation system.

(3) Chemical control is finally sprayed with 1% Bordeaux solution before the onset of the disease, and 50% carbendazim or 50% thiophanate wettable powder 800 times or 50% carbendazim 800 times can be sprayed after the attack.

Commonly used agents carbendazim, topiramine wettable powder, carbendazide.

 
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