Rhododendron gall disease
Symptoms: it can harm the twigs, shoots and leaves of rhododendron. After the injury of the leaf, the margin or the whole leaf was swollen and hypertrophic, showing tumor-like or hemispherical fleshy gall. After the twig was damaged, it also swelled and thickened into fleshy galls, affecting the shoot. After the flower is damaged, the white powdery mildew layer appears on the petal surface or depression, that is, the seed layer of the pathogen. In the later stage, the galls turned brown and withered and fell off.
Pathogen and morbidity status:
Pathogens: hemispherical exobasitic bacteria Exobasidiumhemisphaer-icumShirai, basidiomycetes subphylum, stromatomycetes, exobaromycetes.
The law of the disease: the mycelium overwintered on the remains, and the basidiospores began to be produced when the average temperature rose to about 10 degrees Celsius and the relative humidity reached more than 80% in the following year. Basidiospores spread with wind and rain, infecting young leaves, shoots or petals. Half a month later, the disease department began to change color and wither, and the diseased leaves withered and fell off completely in about 25 days. The peak period of the first incidence was from late March to the first and middle of April, and the second peak was in late September.
Prevention and control measures:
1. Disease-resistant varieties were selected.
2. The diseased tissue was removed and destroyed in spring and autumn, and the remains of the rhododendron garden were removed and destroyed in time in winter.
3. In the first ten days of March and the middle of September, spray 15% chlorpheniramine wettable powder 1500 times liquid, or 80% Dysen zinc wettable powder liquid, or 50% bacillus special wettable powder liquid.
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What are the common diseases of rhododendron? How to prevent and cure?
The main diseases of rhododendron are root rot, brown spot, black spot, leaf blight, iron deficiency chlorosis and so on. After the rhododendron suffered from root arm disease, the growth was weak, the leaves wilted and withered, the surface of the root system appeared water-stained brown fields, serious soft rot, gradually rotted and peeled, and the xylem blackened. The disease is most likely to occur in an environment with high temperature and high humidity. The prevention and control method is to strictly disinfect Pei 10 soil before turning the basin, and keep the soil condition sulfur loose, moist, make it have good permeability, and avoid stagnant water. If the plant is found to be sick, it should be dealt with in time.
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How should azaleas be fertilized?
Rhododendron is a kind of flower that does not need big fertilizer. If the fertilizer is applied too much or too thick, it will be harmful to its growth. But this does not mean that it should not be fertilized, but that it should bloom more and more, and that the sky should apply some fertilizer at the right time and in the right amount. Therefore, flower growers summed up eight words of experience in fertilization: "less dry fertilizer, less liquid fertilizer". This is very appropriate and worthy of reference by florists. In general, 1. 2-year-old seedlings do not need to apply fertilizer, because the fertility contained in humus soil is enough to meet the needs of seedling growth and development. two
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