Comprehensive prevention and control of spruce sowing seedlings in greenhouse

In order to shorten the cultivation years of spruce seedlings in high and cold mountain areas, greenhouse is usually used to raise seedlings. The special environment of the greenhouse creates conditions for the breeding and spread of all kinds of diseases that cause the quenching of spruce seedlings. Improper prevention and control will lead to seedling failure. In order to prevent the collapse of newly sown spruce seedlings in greenhouse, we should adhere to the principle of "prevention first and comprehensive control".

1 symptoms of sudden collapse

The symptoms of stunting can be divided into four types: (1) the seeds and ununearthed buds rot and die in the soil after sowing, and there are often arachnoid hyphae around the seeds; (2) within 30 days after the seedlings are unearthed, the stems of the seedlings are waterlogged, rotten and constricted, and the seedlings lodge and die; (3) the young leaves and stems of the seedlings rot, sometimes produce white filaments, and the stems and leaves wilt and rot. (4) after the Lignification of the stem base of the seedling, the root rotted and the seedling died upright.

2 sudden collapse of pathogen

Suddenly, it is the enemy of spruce newly sown seedlings. The quenching of greenhouse spruce is caused by fungi (mainly Rhizoctonia, Fusarium, Pythium), bacteria, mycoplastids, viruses and other pathogens; the other is caused by nutritional conditions, temperature, humidity, toxic substances, light, gases and other unsuitable for the growth of spruce seedlings.

3 prevention and control technology

3.1 seed treatment

When purchasing seeds, the origin of spruce seeds should be strictly checked, without unquarantined and unmarked seeds. It is best to use excellent full seeds picked in the autumn of that year or the year before. The seeds were disinfected with dimethicone and potassium permanganate, and then the seeds were soaked in snow or warm water to keep the soil moist before emergence.

3.2 soil treatment

The greenhouse seedbed shall not use sticky weight and former soil as crop soil. Where there are conditions, it is best to improve the nursery soil with loose and fertile forest humus soil with a thickness of 20-30cm, and then disinfect the soil with 2g dimethicone per square meter + 3G pentachloronitrobenzene, or apply ferrous sulfate powder plus 20g per square meter, apply potassium phosphate fertilizer 50kg at 3:1 per 667m2, and increase the application of plant ash, which can promote seedling growth and improve seedling lodging resistance.

3.3 sowing date

In high and cold mountain areas, seedlings are raised in greenhouse and can be sown all the year round. In the middle and low altitude areas, it is proved by practice that the newly sown spruce seedlings have the strongest lodging resistance when they are sown from early February to mid-March in spring and from early September to early October in autumn.

3.4 Management methods at seedling stage

The main results are as follows: (1) after years of production practice, the lodging resistance of newly sown seedlings in chemical herbicide area is stronger than that in artificial herbicide area. The specific method is to suppress the bed surface after sowing and covering the soil, and then use the net effective amount of 60g/667m2, 40kg with water, and spray evenly on the bed surface with a sprayer, and the weeding effect is more than 90%. After the seedlings were unearthed, the seedlings grew stronger and the lodging resistance was much stronger than that in the untreated area.

(2) cover the soil with yellow core soil after sowing, and the thickness should be 2cm. After emergence, the seedlings were evenly sprayed with 0.5% Ru 1% Bordeaux solution for 2-3 times every 10 days, and the dosage of 60kg/667m2 was used each time.

(3) when it is found that there is lodging in the seedlings, pull out immediately, sprinkle 0.1% Mel 0.2% solution of dimethopone, and sprinkle plant ash between the rows of seedlings, which can effectively control the quenching of seedlings. Within 1-2 months of seedling emergence, high temperature and humidity, low temperature and high humidity, and hot and dry indoor air are the main causes of seedling lodging, so we can artificially control indoor environmental factors such as light, heat, water and air, and strengthen ventilation to prevent and control seedling lodging.

The key to prevent the quenching of newly sown spruce seedlings in greenhouse is to improve the technical level of raising seedlings, manage greenhouse scientifically, strictly control all links, and always adhere to the guiding ideology of "prevention first, comprehensive control", so as to effectively control the quenching of newly sown spruce seedlings. (Xie Yun, Zhao Bo, Xia Jinchun)