What are the key techniques for cultivating and planting yellow chrysanthemums?
1. Site selection: Chrysanthemums like moisture but fear drying out, and are intolerant of waterlogging. If they are submerged by heavy rain for 48 hours after planting, they will all die. Therefore, choose land that is fertile, easy to drain and irrigate, and has sufficient light.
2. Raising seedlings: (1) Fresh cut flowers for the Spring Festival market: raise seedlings in July-August. Transplant in mid-August to early September. Begin artificial lighting 7-15 days after transplanting, for 2-3 hours each night, and stop the lighting 75-85 days before the Spring Festival. (2) Potted chrysanthemums for the Spring Festival: raise seedlings in August-September, transplant in early October, with the rest the same as for fresh cut flowers. (3) Fresh cut flowers for the Qingming market: raise seedlings from mid-October to early November, transplant from late October to early November, and give artificial lighting 3?/FONT>7 days after transplanting, stopping the lighting 75 to 85 days before Qingming.
3. Transplanting: Generally, make beds with a total width including the furrow of 110-120 cm, a bed surface width of 40-50 cm, a working row of 60-70 cm, and a bed height of 13-15 cm, later hilling up to a height of 18-20 cm; land converted from rice fields can be hilled even higher. The planting spacing depends on the variety, the customer and the market. Generally, for single-head chrysanthemums with thick stems and tall plants grown as New Year flowers, the row spacing is 8-9 cun and the plant spacing is 5-6 cun, with 2 rows per bed; others can be planted more densely, with 3-4 rows per bed, at a spacing of 5x5 or 6x6. About 6,000 to 10,000 plants are planted per mu.
4. Fertilisation: (1) Base fertiliser: apply 1,500 jin of human and livestock manure per mu. (2) Top dressing: after the chrysanthemums are transplanted, apply chemical fertiliser once every 10 days. For each crop of chrysanthemums, a total of about 200 jin of imported compound fertiliser, 100 jin of urea and 50 jin of potassium chloride is applied. For potted flowers, this can be reduced appropriately.
5. Bud pinching: after planting, when the chrysanthemum seedlings are 10 cm tall, pinch the buds, keeping 3 side buds. This leaves about 18,000 to 20,000 flowering stems per mu. For single-head chrysanthemums, all side buds that grow later are removed, leaving only the terminal bud to flower. For multi-flowered chrysanthemums, when the plant grows to 70 cm tall, pinch the terminal bud once more, so that the flower buds at the top grow evenly and attractively. If the flowering period is early, more side buds can be kept, which can delay flowering. If the flowering period is late, fewer flower buds can be kept, to make it flower earlier.
6. Loosening the soil, hilling up, and netting management: (1) Loosening the soil and weeding: if the soil becomes compacted after rain following planting, loosen the soil while weeding, and remove the lower basal leaves. (2) Hilling up. About 60 days after planting, after applying compound fertiliser heavily once more, hill up the soil high, piling the mud from the walking paths onto the flower heads. This helps the chrysanthemums root and prevents lodging. (3) Netting: put up the net immediately after hilling up, and thereafter raise it appropriately according to the growth height of the chrysanthemums. Generally, bamboo poles 1.5 m tall are used, driven 50 cm into the ground, with one bamboo pole every 23 m on both sides of each bed, and pulled tight at both ends to prevent lodging.
7. Pest and disease control: (1) Aphids, thrips, leaf miners, stem borers, etc. Control pesticides include omethoate, permethrin, fenvalerate, fenpropathrin, methamidophos, imidacloprid and others. (2) Mites: red spider mites, rust mites, etc. Control pesticides include propargite, fenbutatin oxide, tetradifon, amitraz, chlorfenson, isocarbophos, dichlorvos and others. (3) Underground pests. Cutworms, scarab beetle larvae, etc. Control pesticides include carbofuran, aldicarb, dimehypo, isofenphos-methyl and others. (4) Leaf nematode disease. Control pesticides include carbofuran, aldicarb, mecarphon and others. (5) Sheath blight, leaf spot, rust. Control pesticides include: leaf spot spirit, chlorothalonil, baike emulsifiable concentrate, thiophanate, colloidal sulfur, miebingwei, zhibingling, carbendazim, haoshengling and others.