Sand seedling cultivation: soak the selected seeds in hot water at 50℃ for 4 hours, take them out, put them in a dish filled with coarse sand, accelerate germination at 25℃ and 75% humidity, and plant them after 1 ~ 2 true leaves and 1 cm roots grow.
Cutting seedlings: Use stems and roots that are not lignified before budding as cuttings. The seedbed should be made of sand, and some pond mud can also be mixed. Cut the branches into 2 ~ 3 sections, insert them into the holes tamped with wooden sticks and compact them, leaving bud sections. The density is about 3×5 cm. The seedbed should be shaded and take root in about 7 days. The harvest time of chrysanthemum leaves should be determined according to the climatic conditions and cultivation techniques in the cultivation areas. When plants sprout, the content of inulin in leaves is the highest, so it should be harvested in time. When harvesting, cut 20 cm off the ground. If it overwinters naturally, leave some leaves for protection.
Plants that need to collect seeds can be treated with short light, that is, stevia rebaudiana is shaded at the peak growth period (90 days after emergence), that is, shaded at 6 o'clock in the evening, uncovered at 8 o'clock in the morning the next day, and blooms and bears fruit after continuous shading for 20-25 days. The seeds are very light, so you can cover the plants with plastic bags and pat them for harvesting.
Harvest and processing usually have the highest glycoside content in the whole bud stage. South of the Yangtze River 1 year can be harvested three times, along the Yellow River twice, and in the north 1 year. When harvesting, cut off the branches and leaves, take off the leaves and dry them in the sun or oven. Large-scale planting should be processed and dried by a dryer. 667m2 can produce dry leaves 150~200kg, and the highest can reach 500kg. (1) Rice sheath blight is a seedling disease. Prevention and control methods: ① You can choose plots with good drainage and loose soil to raise seedlings; ② Before sowing, treat the soil with 50% carbendazim 2kg/mu; ③ At the initial stage of the disease, spray with 1000- 1500 carbendazim or irrigate with 500 times solution; ④ Pull out the diseased plants in time, and treat the diseased spots with 3 ∶/kloc-0 ∶ mixed powder of plant ash and quicklime.
(2) July-10 is prone to leaf spot, which is harmful to stems and leaves. Control methods: ① pay attention to drainage to reduce soil moisture from May to June, and apply more potassium fertilizer to improve plant disease resistance; ② Spraying 50% carbendazim l000 times solution at the initial stage of onset; (3) Clean up the garden after harvest, dispose of the remaining plants and burn them centrally.
(3) There is more rainfall in April-May, and the soil moisture is too high, which is easy to cause diseases and damage the roots. Prevention and control methods: ① reasonable close planting, pay attention to ventilation and light transmission in the field; (2) Increase the application amount of phosphorus and potassium fertilizer to prevent the seedlings from growing in vain; (3) Once the diseased plant is found, it should be pulled out immediately, and lime should be sprinkled around the diseased site for disinfection; ④ At the initial stage of the disease, 50% carbendazim can be used to flush the ward with 1000 times to control the spread of the disease.
(4) Prevention and control methods of inchworm (inchworm, bridge builder): the natural enemies of inchworm can be protected, or sprayed with 40% omethoate l000 times dilution, which is forbidden 20 days before harvesting.