The occurrence of diseases in garden seedlings not only affects the normal growth of garden seedlings, but also affects their ornamental value and economic benefits. The occurrence and prevention of common diseases in garden seedling cultivation and management are described below:
Rust
1.1 Symptoms Rust mainly affects the leaves, stems and buds of seedlings. The diseased leaves usually have small yellow projections on both sides. After ripening, they break up and give off orange-red summer spore powder; chestnut brown powder or rust-colored powder is scattered in late autumn and early winter.
1.2 Disease characteristics Rust is a fungal disease caused by rust, with a single host parasitic rust disease and rust disease transferred to the main parasitic. The pathogenic uredia spores can infect the plants repeatedly; the teliospores are lurking in the buds for winter and spring in the following year, producing basidiomycetes, spreading with the wind, and invading the leaves and other organs.
1.3 The control method can be sprayed with Ba 0.3-0.5 degree lime sulfur or 50% trehalose 500 times, and cut off the damaged leaves as soon as possible.
2 Powdery mildew
2.1 Symptoms Powdery mildew is a fungal disease. At the beginning of the disease, the diseased part had a layer of white powdery mildew, which was the conidia of the asexual generation of the pathogen; the mildew-like layer of the powdery mildew became gray at the later stage of disease, and black spots appeared at the affected part. The diseased leaves of the victim plant are not flat, the leaves curl toward the back of the leaves, the plants are short, the young leaves are twisted, deformed, withered, and the branches are deformed.
The whole plant died.
2.2 Characteristics of the disease Powdery mildew is a fungal disease caused by various powdery mildew species in Ascomycetes. The pathogenic bacteria use mycelia or conidia to overwinter on diseased shoots, diseased shoots or fallen leaves. In the spring of next year, germinate with white powder, which is heavier in the early summer and late autumn. Excessive application of nitrogen fertilizer, poor ventilation, are easy to induce powdery mildew.
2.3 Prevention methods
1) Combine pruning, cut sick leaves, and burn them together.
2) Strengthen cultivation and management, increase phosphorus and potash fertilizers, control nitrogen fertilizers, and pay attention to ventilation and light transmission.
3) Prior to germination in early spring, spraying Baume 3 to 4 degrees lime sulfur agent can eliminate overwintering germs; at the early stage of disease, spraying 50% carbendazim WP 800 to 1000 times or 25% Triadimefon 1000 to 1500 times liquid.
3 Blight
3.1 Symptoms The bacteria invade the roots and stem bases of the seedlings from the surface of the soil, causing the diseased parts to turn yellow and rot, and then turn dark brown. When the seedling tissue is not lignified, it is a tumbling phenomenon; when the seedlings have been semi-lignified or lignified, the symptoms of piling up appear.
3.2 Characteristics of the disease The pathogenic bacteria in the soil in the winter through the mycelium, mainly through soil and fertilizer spread, often occurs in high temperature and humidity environment, soil temperature is easy to occur when 15 ~ 20 °C
Disease.
3.3 control methods
1) Disinfect the soil and apply 40% formalin 50 ml water 8 to 12 liters per square meter and pour the soil surface.
2) Remove the diseased plant as soon as possible and concentrate on burning it.
3) Strengthen air and light transmission and strictly control watering.
4) After emergence of the seedlings, the seedbeds may be sprayed or poured with ferrous sulfate, Bordeaux or thiophanate.
4 Brown spot
4.1 Symptoms The disease is a fungal disease. Starting from the lower leaves of the plants, the upper leaves gradually spread, and the lesions were initially round or oval-shaped, purple-brown in the early stages, and black in the late stage.
4.2 Characteristics of the disease The pathogenic bacteria in the dead leaves or soil in the winter, with the spread of wind and rain, serious damage in the fall. High temperature and high humidity, over dense plants, lack of light, poor ventilation, and continuous cropping of the soil are prone to the disease.
4.3 Prevention methods
1) Pay attention to ventilation and strengthen management.
2) Spray 50% carbendazim WP 500 times or 0.5% to 1% Bordeaux mixture at the onset of the disease.
5 yellowing disease
5.1 Symptoms The diseased plants become yellowish, withered, and even fall off.
5.2 Disease characteristics Due to malnutrition, iron or magnesium deficiency causes morbidity; scale insects, spider mites and other pests can also cause yellowing disease.
5.3 Methods of Prevention and Control
1) Improve the cultivation environment and eliminate harmful diseases.
2) Yellowing disease caused by pests, pest control and disease prevention, can be sprayed with 70% trichlorfon 1000 times to prevent and control.
6 White rash
6.1 Symptoms The disease is also known as root rot. At the beginning of the disease, brownish irregular lesions were formed on the base of the stem, followed by white hyphae and gradually changed to the sclerotia of the rapeseed sclerotia. The sclerotia turned brown from white to yellow. The base of the stem rots and necroses, and the plants wither and die.
6.2 Onset characteristics Sclerotia is overwintering in the sick or in the soil. The mycelium invades the host after germination, and has a severe onset in the high-temperature and high-humidity seasons. Its optimal growth temperature is 30 to 35 °C.
6.3 Prevention Methods
1) Strengthen management, pay attention to ventilation and light transmission.
2) Remove the diseased plants and disinfect the soil.
3) Water the plant base and surrounding soil with 50% carbendazim wettable powder 500 times.
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