High-yield and high-quality cultivation techniques for garlic in the Hangzhou area

Garlic is a plant of the genus Allium in the family Amaryllidaceae (Liliaceae) and is an important pungent vegetable. At present, the garlic planting area in China is gradually expanding. In addition to the main producing areas of Shandong Province, Jiangsu Province and Henan Province, it is also widely cultivated in other regions, among which the Yangtze River basin is also an important garlic producing area. Due to differences in climatic conditions, garlic cultivation techniques in each region have their own characteristics, and the cultivation and management methods also differ from those in other regions. The high-quality and high-yield cultivation techniques for garlic in the Hangzhou area are introduced as follows.

1 Site selection and land preparation

Garlic likes fertilizer and water, and its root system has very weak water absorption capacity, so the soil should preferably be fertile, well-drained sandy loam. Garlic is not suitable for continuous cropping, and crops such as scallion, Chinese chive and onion should not be used as the previous crop. Early-maturing crops such as dwarf bean, cucumber, tomato, potato and corn can be chosen as the previous crop, and it can also be intercropped or relay-intercropped with grain crops. For autumn-sown garlic in the Yangtze River basin, the land is generally plowed and sun-dried in time after the previous crop is harvested. Before plowing, apply 4000-5000 kg of decomposed farmyard manure, 100-150 kg of cake fertilizer, 50 kg of standard nitrogen fertilizer, 30 kg of phosphate fertilizer and 30 kg of potassium fertilizer per 667 sq m, then carry out fine cultivation, level the land and make beds. The bed surface width is 1.5-2.0 m, and high beds with deep furrows are made to facilitate drainage.

2 Selection of improved varieties

Choose garlic varieties with large bulbs, high yield and strong disease resistance. The main cultivated varieties in this region include Jiading garlic, Xuzhou white garlic, Hangzhou white-skinned garlic and Sichuan Chengdu Ershuizao. Among them, Jiading garlic, Xuzhou white garlic and Hangzhou white-skinned garlic belong to the white-skinned type, with large bulbs and relatively mild pungency; Sichuan Chengdu Ershuizao belongs to the purple-skinned type, with bulbs of varying sizes, fewer cloves and relatively stronger pungency.

3 Timely sowing

3.1 Selection and treatment of garlic cloves

Garlic cloves used for sowing should have the typical characteristics of the variety, large bulbs, no damage and no deformity. Before sowing, grade the garlic cloves, and do not mix large and small seed garlic together, so as not to affect yield and quality. In production, in order to break dormancy and promote germination, the garlic skin can be removed before sowing, or the garlic cloves can be soaked in water for 1-2 days before sowing, or soaked in a 500-fold solution of 50% carbendazim for 10-12 h, then removed, air-dried and sown. In addition, placing garlic cloves at a low temperature of 0-4°C for 1 month can greatly advance germination.

3.2 Sowing time

Garlic is a cold-loving crop and is suitable for winter planting in the south. The optimum temperature for germination is about 22°C, the optimum temperature for stem and leaf growth is 15-20°C, and the optimum temperature for the late growth stage is about 25°C. In the Hangzhou area, autumn sowing is generally carried out after garlic dormancy. For cultivation mainly aimed at harvesting bulbs, the sowing period is somewhat later than in the north, mostly in mid-to-late September, with harvest in June of the following year.

3.3 Sowing density and sowing rate

Sow by grade, inserting the selected garlic cloves directly into the soil, not too deep, with the tips slightly exposed. When the main cultivation purpose is harvesting bulbs, the plant spacing and row spacing are (15-20) cm x (10-13) cm, and the sowing rate per 667 sq m is 66.7-133.3 kg. The larger the plant spacing and row spacing, the greater the single-bulb weight of the bulb, but deformed bulbs are more likely to occur. After sowing, cover with soil 2-3 cm deep and compact the covering soil so that it is firm on top and loose below. In dry weather, water immediately after sowing to keep the soil moist.

4 Field management

After emergence, carry out intertillage and loosening of the soil in time. During the growth period of green garlic, topdressing should be applied 2-3 times to promote aboveground growth. Intertillage and weed control are especially important after the garlic seedlings emerge. When the seedlings are 10-15 cm high, intertillage can be deeper; when the seedlings are more than 30 cm high, intertillage should be shallower. Generally, intertillage and watering are combined with fertilization. In addition, when the purpose is to produce garlic bulbs, apply 30-40 kg of bio-organic fertilizer per 667 sq m before overwintering, and water once in time after fertilization to ensure that the seedlings overwinter safely.

After the weather warms in the following spring, repair the water furrows so that drainage can be carried out in time. Spring is a vigorous growth period for garlic plants and also a vigorous elongation period for garlic scapes, and the plant's absorption of nitrogen, phosphorus and potassium rises rapidly. Apply fertilizer once in early March, with 20-25 kg of ammonium sulfate per 667 sq m, to promote bolting and accelerate the growth and development of garlic cloves. Apply a heavy fertilizer once at the end of March, with 20 kg of urea and 20 kg of compound fertilizer per 667 sq m, while paying attention to watering, mainly to keep the soil moist. In April-May of the following year, the bulbs have begun to expand, and there is a lot of rain, so attention should be paid to drainage; otherwise, the garlic cloves are likely to spread apart. The use of chemical herbicides such as pendimethalin and trifluralin, combined with colored film mulching, has a good weed control effect.

Try to water as little as possible 3-4 days before harvesting garlic scapes. After the garlic scapes are harvested, the garlic bulbs enter a vigorous expansion period. At this time, plant growth is slow, and generally no more topdressing is applied. If the soil is dry, water frequently in small amounts to keep the soil moist, so as to lower the soil temperature and promote expansion. Stop watering 5-7 days before harvesting the garlic bulbs to promote bulb maturity and enhance storability.

5 Pest and disease control

In the Yangtze River basin, the main garlic pests and diseases are leaf blight, soft rot and garlic maggot. The control principle is prevention first, with integrated control.

By strengthening field management, rational close planting, increasing the application of complete nitrogen, phosphorus and potassium fertilizers, adding bio-antibacterial fertilizer, cultivating strong seedlings, timely drainage after rain, and preventing waterlogging in the field, garlic pests and diseases can be effectively controlled. For leaf blight, in the early stage of the disease, spray 600-fold 75% chlorothalonil wettable powder, 1500-fold 50% iprodione wettable powder, 500-fold 64% oxadixyl wettable powder, 400-fold 25% mancozeb or 1000-fold 50% procymidone for control, once every 7-10 days, for 3-4 consecutive applications; for soft rot control, before the disease or in the early stage of the disease, use 3000-4000-fold 72% agricultural streptomycin, 1000-fold 50% amobam or 3000-4000-fold xinzhiromycin, spraying once every 5-7 days, for 2-3 consecutive applications depending on the disease situation; for pests such as onion thrips and aphids, spray 3000-fold 25% cyhalothrin emulsifiable concentrate, 1000-fold 24% methomyl aqueous solution or 1500-fold 505 menazon emulsifiable concentrate for control; for garlic maggot control, use 1000-1500-fold 50% phoxim or 800-fold 80% dichlorvos emulsifiable concentrate to spray-irrigate the affected garlic plants, once every 4-5 days, for 2-3 spray-irrigations depending on the pest situation. During the larval stage, 1200-fold 90% crystal trichlorfon can be used for root drenching.

6 Timely harvest

6.1 Harvesting garlic scapes

After differentiation, garlic scapes elongate quickly and need to be harvested in time; otherwise, the yield of garlic bulbs will be affected. In early May, when the garlic scapes emerge from the leaf sheath and the flower bud is slightly flat-hammer shaped, they can be harvested. Harvest on a sunny afternoon, generally picking below the third leaf from the lower part of the garlic scape. To bring them to market earlier, harvest when the garlic scape is about 7 cm above the mouth of the leaf sheath of the last leaf and the upper part has not yet bent; when the goal is to increase garlic scape yield, harvest when the garlic scape is about 15 cm above the mouth of the leaf sheath of the last leaf and the upper part bends downward.

6.2 Harvesting garlic bulbs

Garlic bulbs can begin to be harvested 20-30 days after the garlic scapes are harvested. At this time, most garlic leaves are withered, the upper leaves fade and then the leaf tips dry and droop, and the plant is in a soft state, so the garlic bulbs can be dug out. After harvest, dry them in the field for a few days, then bundle and braid them into bunches, and store them in piles or hang them in a cool place. During the drying process, it is necessary both to prevent the garlic bulbs from being damaged by the scorching sun and to pay attention to weather changes to prevent rain damage.