Key Technical Points for High-Yield and High-Quality Cultivation of Garlic with Plastic Mulching

Garlic is currently one of the main cultivated vegetables in the Laixi area, with a cultivation area of over 200,000 mu over the years. To increase the economic income of local garlic farmers, since 1998 we have conducted experimental research and extension of large-scale high-yield and high-quality garlic cultivation technology with plastic mulching. In the demonstration park, the average yield per mu is 1,000 kg of garlic scapes and 1,000 kg of garlic bulbs, with the highest yield per mu exceeding 1,250 kg. The garlic scapes produced are green and tender, and the garlic bulbs are plump, white, strongly pungent, and highly viscous, with strong market competitiveness. They are exported in large quantities, and the economic benefits are considerable. The main techniques are summarized below.

I. Selection of garlic seed. Choose Laixi Big Six-Clove or Cangshan garlic, which has high scape yield and white bulbs, as the seed garlic. Among these, the Laixi Big Six-Clove, which we have bred through systematic selection and optimization in recent years, has a plant height of 80-100 cm, dark green leaves, strong growth vigor and disease resistance, scapes about 70 cm long, green in color and tender in quality, with good floury texture, bulb transverse diameter of 3.5-5.0 cm, single bulb weight of about 40 g, white color and good appearance, with an average of 6-7 cloves per bulb, strong pungency, and good viscosity. Before sowing, select bulbs conforming to the characteristics of this variety as seed, choose plump outer cloves that are free of insect holes and disease spots, and remove the small cloves in the middle of the bulb, so as to facilitate uniform growth and easy management. Generally, about 200 kg of cloves are needed per mu.

II. Apply sufficient basal fertilizer and prepare the land finely. Choose plots with fertile soil, good water and fertilizer retention, and irrigation conditions, and level them carefully to prevent uneven irrigation. After leveling, evenly broadcast 2,500 kg of decomposed pig manure and 75-100 kg of potassium sulfate compound fertilizer with nitrogen, phosphorus, and potassium contents of 15% each per mu on average, then use a rotary tiller to till the soil finely, so that the soil is loose on top and firm below, with no visible or hidden clods.

III. Sow at the appropriate time and plant at a reasonable density. Garlic is divided into spring sowing and autumn sowing depending on the region, but spring sowing has low yield and poor quality, so it should not be adopted. Autumn sowing is generally suitable from the Autumn Equinox to Cold Dew, with 5-6 leaves grown before winter, a plant height of 20 cm, and a stem diameter of 0.8 cm being ideal. If sowing is too late, the seedlings have poor cold resistance and are prone to freezing injury and death.

The sowing method is as follows: after leveling the land, use a farmer's two-tooth hoe or a four-tooth garlic rake specially made according to the planting row spacing to draw shallow furrows 1 cm deep, sow the cloves at a plant spacing of 6 cm, inserting 4/5 of the clove, with 1/5 of the clove exposed so that it does not fall over. After inserting, immediately build soil from the large rows between the beds and the large rows on the beds into furrows to cover the garlic, with about 1.5 cm of soil cover. Then irrigate thoroughly through the furrows between the beds and the furrows on the beds. After 5-7 days, when the soil surface is slightly dry, use an iron rake to level the garlic ridges on the beds, taking care to rake lightly to avoid pulling out the cloves. After leveling, spray the bed surface carefully with a 500-fold dilution of 50% acetochlor emulsifiable concentrate, and finally cover with plastic film. The plastic film covers the furrows on the beds within the film, and subsequent irrigation is carried out simultaneously through the furrows on the beds inside the film and the furrows between the beds. This planting method not only provides uniform irrigation and keeps the soil loose without compaction, which is conducive to uniform garlic growth, early scape maturity, and high yield, but also facilitates garlic bulb harvest, makes it less likely to break seedlings, and improves bulb grade.

IV. Field management. After garlic sprouts, promptly break the film to release the seedlings. The method is to take advantage of the early morning when the sprout tips have just emerged from the ground and the cotyledons have not yet unfolded, and use a small broom used by farmers for sweeping the ground or a small mop made from corn husks to gently pat or lightly sweep the plastic film, and the sprout tips will break through the film and emerge. Releasing seedlings should be carried out continuously every morning for 5-6 days. If a small portion of sprouts are still trapped under the film, use a small wire hook to break the film and gently lift the seedlings out, so that every garlic seedling grows normally. If there is a long drought without rain after sowing, water once 30 days after emergence. In early winter there are fewer garlic seedlings and strong winds are common. If the film is lifted by wind, it must be re-covered promptly. After the Start of Winter, based on the weather and soil moisture, water once with overwintering water. After the Awakening of Insects the following year, promptly water with green-returning water, and apply 30 kg of urea per mu washed in with the water. After that, depending on growth, apply 20 kg of urea per mu washed in with the water before scape emergence. Garlic has a very high water requirement, and watering sufficiently is very important. Generally, from green returning to before scape harvest, it should be watered 4-5 times. Stop watering 4-6 days before scape harvest to facilitate harvest. After scape harvest, irrigate promptly and spray the leaves once with 0.3% urea or monopotassium phosphate or a 500-fold dilution of photosynthetic micro-fertilizer to improve leaf photosynthetic function and promote continued bulb enlargement and weight gain.

V. Disease and pest control. Garlic has relatively few diseases and pests, but when 70-80% of garlic seedlings have emerged and when garlic mothers rot in spring, it is prone to damage by root maggots, with spring damage being the most serious, often causing plant root rot. Leaves turn yellow, wither, and even die in patches. Because garlic maggots are attracted to decay, apply fully decomposed fertilizer, and avoid using raw manure or planting slightly rotten cloves. In spring, before the garlic mothers rot, pour a 800-fold dilution of 90% trichlorfon or a 800-fold dilution of 80% dichlorvos or a 600-fold dilution of 40% isofenphos-methyl at the garlic roots to kill the larvae. After that, pay attention to using a 600-fold dilution of 75% chlorothalonil or a 500-fold dilution of 64% oxadixyl plus mancozeb to control garlic leaf blight.

VI. Harvest at the appropriate time. The timing of scape harvesting has a great influence on the quality and yield of garlic scapes. Harvesting too early results in low yield and poor quality. Harvesting too late not only consumes too many plant nutrients and reduces bulb yield, but also causes the bulb tissues to become old and tough, reducing quality and edible value. The suitable harvest period for garlic scapes is when the scape has grown out of the leaf sheath and begun to curve its tail, and the spathe has bent above the plant and is about to coil. After the garlic scapes are harvested, 15-20 days later, when most of the garlic leaves have turned yellow and withered, the bulbs can be harvested. When harvesting bulbs, be careful not to break the garlic seedlings. Once the seedlings break, the bulbs will scatter their cloves and turn yellow, failing to meet export grade requirements. After the bulbs are dug out, they can be dried directly in the field for 5-6 days in good weather. Note that the bulbs should be placed under the garlic seedlings to prevent damage from excessively strong sunlight, and turn them once every 3-4 days. When the garlic seedlings are basically dry, take advantage of the early morning or evening when the seedlings absorb moisture and become soft, and tie the bulbs together with the seedlings into bundles, then stack them in a dry, cool, and ventilated place for storage. Once prices rise, the bulbs can be cut off and sold by size grade.