Detailed Explanation of High-Yield Cultivation Techniques for Shuili Local Red Shallot

Shallots have a long history of cultivation in the Guangzhou area, and red-headed shallots (red shallots) are especially favored. Shuili local red shallot is a local variety from Shuili Village, Baiyun District, Guangzhou, with a plant height of 55-70cm and a spread of 30cm. Leaves are 35-50cm long, 0.9-1.2cm in transverse diameter, green, with little wax bloom. The white portion (pseudostem) is 15-20cm long, 1.5-2.0cm in transverse diameter. Small bulbs form at the base, spindle-shaped, with scale tunics ranging from purplish red to brownish red and white flesh. The plant has strong growth vigor and strong tillering ability. It takes 50-70 days from planting to first harvest, with a yield of 5000kg per 667 sq m. It is resistant to wind and rain, has strong cold resistance, and has a rich fragrance. Drawing on the cultivation experience of farmers growing red shallots, and through experimental research and production practice, a set of high-yield cultivation techniques for Shuili local red shallot has been summarized.

1 Preparations Before Sowing

(1) Site selection: Choose sandy loam soil with ample sunlight, convenient drainage and irrigation, deep and fertile plow layer, rich organic matter and loose texture, and strong water retention capacity. The previous crop should be a non-allium vegetable crop, preferably with paddy-upland rotation.

(2) Land preparation: First deep plow and sun-dry the soil clods, then break up and level the bed surface, forming deep furrows and wide beds. Generally the bed width is 2m (including furrows), with furrow width of 50cm and depth of 50-60cm. Apply sufficient base fertilizer before land preparation: per 667 sq m, apply 2000-2500kg of decomposed farmyard manure (such as pig manure), 50kg of peanut bran, and 75kg of superphosphate that have been mixed and composted together. During land preparation, ensure fine soil, straight furrows, level bed surface, and even fertilizer distribution. At the same time, spray herbicide pendimethalin at 100-150ml/667 sq m.

(3) Seed selection: Red shallots are propagated from bulbs. Select shallot heads that are large, firm, well-shaped, and undamaged as seed.

2 Sowing and Seedling Management

(1) Timely sowing: The suitable sowing period in the Guangzhou area is from mid-to-late July to the end of September, with the best sowing period being mid-to-late August. The seeding rate is 50-90kg per 667 sq m, generally with a plant spacing of 22cm and row spacing of 25cm, planting 1-2 bulbs per hole. To increase early yield, plant 1 additional row between rows (interplanted shallots), and harvest all plants at once at first harvest. Before sowing, soak seeds in 500 times diluted 50% carbendazim wettable powder solution for 5-10min, remove and air-dry before sowing.

(2) Seedling management: Plant shallowly, with the shallot head buried 2/3 to 3/4 into the soil. After sowing, water thoroughly once, until the bed surface is soaked through. Seedlings emerge in 7-15 days. When seedlings are about 10cm tall, apply a light liquid fertilizer once: per 667 sq m, use 500kg of decomposed human and animal manure water plus 3-5kg of urea applied as a liquid drench to promote root growth and seedling development. Thereafter, topdress every 10 days. The seedling stage occurs in early autumn when the weather is dry, so water every 1-2 days. If high temperature and drought occur at this time, take care to prevent bulb stagnation during the seedling stage.

3 Field Management

When shallot seedlings grow to about 20cm, combine intertillage and weeding with topdressing to promote growth and tillering. Generally apply 20-40kg of compound fertilizer (NPK) and 5-10kg of urea per 667 sq m, along with thorough watering. Watering should be adjusted according to weather conditions, aiming for the bed surface to be slightly white, and watering in the morning and evening. Excessive moisture causes shallot leaves to grow too rapidly, affects pseudostem growth, and makes plants prone to disease and lodging, with the shallot head color turning pale. Thereafter, topdress generally every 10 days. When temperatures begin to rise in spring, appropriately increase P and K fertilizer application, especially K fertilizer.

4 Pest and Disease Control

The main diseases in the Guangzhou area include purple blotch, rust, downy mildew, leaf blight, gray mold, and Phytophthora blight; the main pests include thrips, leafminers, onion flies, beet armyworm, and tobacco cutworm. Pest and disease control should focus primarily on agricultural measures such as crop rotation, removal of diseased leaves, maintaining field sanitation, and controlling water and fertilizer. At the same time, on the basis of physical control methods such as frequency-vibration insect-killing lamps, supplement with chemical control.

(1) Purple blotch: 200 times diluted 40% fosetyl-aluminum wettable powder, 500 times diluted 58% metalaxyl-mancozeb wettable powder, 500 times diluted 64% sandofan wettable powder.

(2) Rust: 1000 times diluted 15% triadimefon, 4000 times diluted 72% agricultural streptomycin, 1500 times diluted 58% cong-suan-bing-ke wettable powder, 600-800 times diluted 30% Nuoxi wettable powder.

(3) Downy mildew: Bordeaux mixture at 1:1:(200-300) dilution, 500-700 times diluted 65% zineb wettable powder, 600 times diluted 75% chlorothalonil for spray control, 200 times diluted 40% fosetyl-aluminum wettable powder, sprayed once every 7-10 days.

(4) Leaf blight: 800-1000 times diluted 70% Landun wettable powder, 500-800 times diluted Xishimei, 1500 times diluted 58% cong-suan-bing-ke wettable powder, 600-800 times diluted 30% Nuoxi wettable powder for spraying.

(5) Gray mold: 1500 times diluted 58% cong-suan-bing-ke wettable powder, 600-800 times diluted 30% Nuoxi wettable powder, 800 times diluted Kangkuling, 600 times diluted 64% sandofan wettable powder for control.

(6) Phytophthora blight: 800 times diluted Kangkuling, 600 times diluted 64% sandofan wettable powder, 600-800 times diluted 30% Nuoxi wettable powder for control.

(7) Tip blight: This disease is a physiological disorder, mainly characterized by chlorosis at leaf tips that rapidly turns yellow and dries up. The dried leaf tip length is 0.5-1.5cm, and can reach 2-3cm in severe cases. This disease mainly occurs at two times of the year: one is in early October when the north wind first arrives, and the other is in March-April when the weather warms and the south wind begins. October outbreaks are the most severe. Preventive measures should be taken in advance, strengthening fertilizer and water management, and spraying foliar fertilizers, amino acids, etc. in advance, which can effectively control the occurrence of the disease.

(8) Onion thrips: When the pest population reaches 50-100 insects per 100 plants in the field, chemical control should be applied immediately. Options include 2500 times diluted 10% imidacloprid, 1000 times diluted 40.7% chlorpyrifos, 1000 times diluted 40% Ji-Ya-Qing, 1000-2000 times diluted 20% Haoniandong, 1500 times diluted 5% fipronil. Spray once every 8-10 days; generally 2-3 consecutive sprays can provide effective control.

(9) Leafminers: Options include 2500 times diluted 10% imidacloprid, 1000 times diluted 40.7% chlorpyrifos, 4000 times diluted 5% Yitaibao, 4000 times diluted 5% Cascade, 3000 times diluted 1.8% abamectin EC for control.

(10) Onion flies: sugar:vinegar:water = 1:1:2.5 plus a small amount of trichlorfon; fermented glutinous rice dregs mixed with a small amount of trichlorfon; 800-1000 times diluted 40% dimethoate for root drenching.

In addition, for beet armyworm and tobacco cutworm, options include 1000 times diluted 20% Mimic suspension concentrate, 1000 times diluted 10% Chujin suspension concentrate, 4000 times diluted 5% Yitaibao, 4000 times diluted 5% Cascade, 500-1000 times diluted 25% diflubenzuron suspension concentrate, 1500-3000 times diluted 20% diflubenzuron suspension concentrate for control.

When applying chemical pesticides, it is best to add an equal amount of anti-resistance agent, such as neutral soap powder, neutral laundry detergent, dishwashing liquid, starch, etc., to enhance adhesion.

5 Timely Harvesting

When the interplanted shallots reach a suitable height, they should be pulled up whole and marketed promptly, to facilitate the healthy growth and tillering of the shallots at regular spacing.

When the shallots at regular spacing are suitable for market, they should be harvested by dividing clumps promptly, i.e., leaving 1-2 plants per hole as mother plants and pulling up all the rest. When pulling shallots, special care should be taken to protect the remaining mother plants, and use a small amount of soil to firm the exposed roots after pulling. When the pressed soil is slightly dry, water once. If pulling is not timely, shallot plants will grow leggy, tillering will accelerate, plants will become increasingly weak, pests and diseases will worsen, and the commercial quality of the shallots will be affected.

6 Seed Saving

In the Guangzhou area, seed saving of red shallots is generally done in the production field. At the end of March to early April, stop pulling shallots, or plant shallowly in high beds with strengthened management. By mid-to-late April, bulbs begin to form round shapes (i.e., bulbs start to become spherical and stop tillering). By May-June, when the pseudostem becomes soft and drooping, harvest the entire plant for seed, and after sun-drying (mainly the pseudostem and outer skin of the shallot heads), hang in a cool place until autumn for sowing again. If saving seed in large quantities, the shallot seed should not be piled up after harvest but spread out for storage; if stored in piles, turn the pile once every 1-3 days.