High-Quality Broccoli Field Management Techniques and Leaf Disease Control Methods

I. Management During the Seedling Recovery Period

The management during this period is mainly cooling and moisture retention, to promote early seedling recovery. In addition to using shade nets to build shelters for shading and cooling, water must be applied once each in the morning and evening. To prevent underground pests from biting off the seedlings, evenly spread Mirel on the soil surface when transplanting. About 7 days after transplanting, apply a light dressing of human manure and urine or a 2%-3% urea water solution to promote plant growth. To prevent and reduce the occurrence of diseases, about 10 days after transplanting, spray once with 75% chlorothalonil 600x solution or 50% carbendazim 600x solution.

II. Management During the Rosette Period

This period is the vigorous vegetative growth stage of broccoli, so sufficient fertilizer and water must be provided to allow the stems and leaves to grow quickly and lay a good nutritional foundation for achieving high yield. During this period, topdressing is needed twice. The first topdressing is when the plants begin rapid growth (about 15 days after transplanting), using a small hoe to open holes between the plants and apply urea, about 15 kg per mu; the second topdressing is carried out before the plants close the rows, when the heart leaves begin to show a twisting-heart shape (about 30 days after transplanting), combining weeding with opening shallow furrows between the rows, applying fertilizer and then hilling soil, applying 20-25 kg of compound fertilizer per mu, or 25 kg of peanut bran. Where conditions permit, it is best to apply human manure and urine once every 7-10 days during this period. In the early rosette period, watering should be sufficient to meet the needs of rapid plant growth and development; after the plants form a full rosette, watering should be appropriately controlled to promote underground root development. Side branches occurring during this period should be removed promptly to promote the formation of the main curd. At the same time, pay attention to pest and disease control, especially the damage from diamondback moth (commonly known as hanging-thread worm), cabbage white butterfly (commonly known as cabbage caterpillar), black rot, and soft rot. For diamondback moth, spray for control from the peak egg-hatching stage to the 2nd-instar larval stage with 5% fipronil 3000x solution or 1% insecticidal toxin 3000x solution, etc.; for cabbage white butterfly, spray for control with Bt emulsion 1000x solution, or fenvalerate 1500-4000x solution, etc.; for black rot and soft rot, in the early stage of disease, alternate spraying with 200 mg/L agricultural streptomycin, or 200 mg/L chloramphenicol, or 75% chlorothalonil 600x solution, or 77% copper hydroxide 500-800x solution, etc.

III. Management During the Curd Formation Period

To promote the transformation from vegetative growth to reproductive growth and favor curd formation, nitrogen fertilizer should be appropriately controlled during this period, with combined application of phosphorus and potassium fertilizers and boron, molybdenum, and other fertilizers. At the beginning of curd formation (40-50 days after transplanting), apply a heavy fertilization once, with 15 kg of potassium chloride and 15 kg of compound fertilizer per mu. To reduce yellowing of the curd surface and hollow stems, and delay plant senescence, during the curd formation period spray the leaf surface with 0.5% borax and 0.5% ammonium molybdate solution, about once every 1 week, for 2-3 consecutive sprays. Throughout the curd formation period, field soil should be kept moist, and diseased leaves and old leaves should be removed promptly, with pest and disease control carried out. For cultivation that also harvests side curds, keep 3-4 healthy side flower branches per plant, and the remaining side flower branches should preferably be removed.

IV. Management During the Peak Harvest Period

During this period, attention should be paid both to promptly removing diseased leaves and old leaves to facilitate ventilation and light penetration and promote nutrient accumulation in the curd, and to controlling moisture to prevent excessive humidity, which can cause disease and curd mold rot. In acid rain or heavy fog weather, water should be sprinkled promptly to wash away the fog water and acid rain, so as to reduce curd rot. The suitable harvest period for broccoli is relatively short. If harvested too late, the curd becomes loose, the flower buds turn yellow, and quality declines; but if harvested too early, the curd is small and yield is low. Generally, the suitable harvest time is when the flower bud particles feel slightly loose to the touch or the flower bud particles at the edge of the curd are slightly loose, and the curd surface is tight and flat without unevenness. Broccoli harvesting should preferably be carried out in the early morning or evening on a sunny day. When harvesting, cut off the curd together with about 10 cm of tender flower stalk, place it in a shaded and cool place, and package it for market as soon as possible. If it cannot be marketed in time, it must be quickly stored at low temperature. For cultivation that also harvests side curds, topdressing should also be applied once after the main curd is harvested, about 15 kg of compound fertilizer per mu, and the side curds should be harvested when they grow to about 5 cm in diameter.