How to Control Abnormal Growth in Garlic? A Detailed Guide to Practical Techniques

Abnormal growth in garlic mainly includes two types: secondary growth of garlic and onion-type garlic. Secondary growth, also known as the regrowth of degenerate leaves in garlic and commonly called "horsetail garlic," refers to the phenomenon where, at the same time the garlic scape emerges, a ring of small garlic leaves grows around the scape. These small leaves grow around the scape, while the growth point of the new cloves shows no sign of sprouting. This abnormal phenomenon means the garlic can neither be kept for seed nor eaten, severely reducing its marketability and economic value.

The causes of secondary growth in garlic are mainly the following:

1) Choosing garlic varieties not suitable for planting in the local region; 2) Planting garlic too early or too late; 3) Unsuitable storage conditions for the seed garlic in the 30 days before planting; 4) Applying excessive nitrogen and phosphorus fertilizer during cultivation, with potassium fertilizer being relatively deficient.

Onion-type garlic, commonly called "bread garlic," shows very robust plant growth before harvest, but the bulb undergoes abnormal deformation. After harvest, when the bulb is peeled open, there are only layer upon layer of skins, with no cloves or only cloves the size of soybean grains. Once onion-type garlic appears in production, it has no market value or edible value whatsoever.

The causes of onion-type garlic are mainly the following:

1) Applying excessive base fertilizer such as nitrogen, phosphorus and potassium during cultivation; 2) Excessive soil moisture content; 3) Not watering in time;

The harm caused by abnormal growth in garlic is very serious. Once this phenomenon appears in production, there is no remedy. Therefore, full-process control must be carried out in garlic cultivation and management.

Site Selection and Land Preparation

Garlic should be planted on land with higher elevation and good drainage, preferably loam or light clay loam with fertile soil, strong water retention and drainage performance, and organic matter content of 1.71%. Garlic prefers cool conditions and is moisture-loving but afraid of drying out; a good soil tilth layer is beneficial to the growth and development of the garlic root system. When the soil is too sticky and heavy, to the point that a handful of soil easily forms a ball when squeezed, onion-type garlic can form. Experiments show that when the relative soil moisture content reaches 90%-100%, 26.06% of onion-type garlic can form. To control the occurrence of abnormal garlic, the plot for planting garlic should be plowed and the ridges sunned early to activate the soil, increase soil permeability, and promote garlic root development and bulb enlargement.

Before sowing, sufficient base fertilizer should be applied all at once in combination with land preparation. Garlic is a shallow-rooted crop, and only by applying sufficient base fertilizer all at once can the nutrient needs of garlic be fully met and the goal of controlling abnormal growth be achieved.

Base fertilizer should be applied using a formula fertilization method. For autumn planting, apply 5000 kg of high-quality barnyard manure, 20 kg of nitrogen fertilizer, 10 kg of phosphorus pentoxide, and 15 kg of potassium oxide per mu. It should be noted that during fertilization, if nitrogen, phosphorus and potassium fertilizers are applied excessively, onion-type garlic will occur. Experiments show that when the application rates of nitrogen fertilizer and phosphorus pentoxide both reach or exceed 40 kg per mu, a large amount of onion-type garlic can be induced.

After the base fertilizer is applied, the land should be deeply plowed to loosen the soil. In production, mechanical deep plowing is usually used, with a plowing depth generally of about 25 cm. The soil should be harrowed level and fine, flat, loose on top and firm below, with no obvious large clods, meeting the standard of "even, loose, fine, and clean."

The quality of land preparation is crucial, as it directly relates to the quality of film mulching and the effect of seedling preservation. If the land preparation quality is poor, with large clods and an uneven soil surface, the plastic film will not cover tightly and will leave large gaps. This not only promotes weed growth but also affects the moisture-retaining and heat-insulating effects of the film, leading to uneven emergence and triggering abnormal growth in garlic.

After plowing, determine the length of the beds according to the location of the water source, and make beds with a length of 40-50 m and a width of 1.5-2 m. Try to keep the width consistent, the bed surface flat, and the bed lines straight.

Careful Selection of Fine Seed

To ensure the yield and quality of garlic and avoid abnormal phenomena, seed cloves must be carefully selected before sowing. The selection of seed cloves should begin in the field after the garlic bulbs are harvested. From the harvested garlic plants, select large-diameter bulbs with single cloves weighing more than 5 g, leaves without disease spots, bulb outer skin of uniform color, plump and round, and outer cloves uniform in size, and keep these individual plants for storage as seed. Remove cloves with damage, disease spots, and those that are too small.

It should be especially noted here that garlic varieties suitable for planting in the local region must be chosen, because an important cause of secondary growth in garlic is heredity. If garlic varieties not suitable for planting in the local region are chosen, the occurrence of secondary growth will be greatly promoted.

After the seed garlic is selected, it should be stored in a cool, ventilated place. When sowing time approaches, the seed cloves must be treated.

Garlic is planted over a relatively wide area in China, and the varieties are fairly complete, with suitable planting varieties in every region. However, to ensure the yield and quality of garlic and avoid abnormal phenomena, seed cloves must be carefully selected before sowing.

Seed Clove Treatment

In production, the method of cold storage of seed garlic is generally used to treat the seed garlic. 10-15 days before sowing, put the seed garlic into a constant-temperature fresh-keeping warehouse, with the temperature inside maintained at about 0°C and the relative humidity kept at 60%-75%, in order to break the dormancy period of the seed garlic. If the seed garlic is cold-stored in an environment with relative air humidity exceeding 75%, the secondary growth phenomenon in garlic will increase markedly.

During cold storage, the warehouse should be kept ventilated and breathable, with no other toxic pollutants inside, to prevent the garlic cloves from becoming moldy and deteriorating. To avoid contamination caused by walking inside the warehouse, if conditions permit, a separate operation room can be set up outside the warehouse, using closed-circuit television to monitor and manage the warehouse.

After cold storage treatment, the seed garlic still needs to be separated into cloves shortly before sowing. The clove separation should not be done too early, to prevent drying and water loss that would affect emergence. The method is to peel off the stem plate of the garlic and remove the leathery skin outside the cloves. Once the garlic has been separated into cloves, it can be sown.

Sowing at the Appropriate Time

The best sowing period for garlic is between mid-to-late September and early October. In northern China, the best suitable sowing period for garlic is five days before and after National Day, that is, from September 25 to October 5. Even in southern China, the most suitable sowing period for garlic should not exceed October 20. Sowing after October 20 easily induces secondary growth in garlic.

When sowing garlic, use a furrow opener to open sowing furrows at a row spacing of 17 cm, with both furrow depth and furrow width kept at about 5 cm. The furrows should be opened to a consistent depth with straight furrow lines. After opening the furrows, evenly scatter the seed garlic on the furrow surface, then sow it into the furrows. This method saves both time and labor and allows flexible control of sowing progress.

It should be especially noted that furrow opening, sowing and covering with soil should be at a consistent depth, so as to benefit the normal growth and development of garlic seedlings and reduce the probability of abnormal phenomena in garlic.

When sowing garlic, special attention should be paid to the insertion orientation of the cloves. A normal garlic clove generally has 3 sides: the back is 1 curved side, and the two sides each have 2 sides that are basically equal in size. The direction in which the garlic leaf blades are attached is perpendicular to the dorsal-ventral line of the clove. Therefore, when placing the cloves, the line connecting the ventral and dorsal sides should be parallel to the row direction, and the cloves should be inserted into the soil according to the plant spacing with the tips slightly exposed. In this way, the curved sides of the cloves all face the same direction, which helps increase sunlight radiation, thereby speeding up garlic germination and reducing the probability of abnormal phenomena.

At sowing, keep the plant spacing at about 15-16 cm, generally maintaining about 25000 plants per mu. If sown too early, due to high temperatures, the cloves sprout slowly, the emergence period is long, the emergence rate is low, the seedlings grow too vigorously before winter, cold resistance decreases, the plants age prematurely, and photosynthesis and nutrient accumulation during the garlic bulb enlargement stage are weakened, making the bulbs smaller and causing secondary growth in garlic. If sown too late, the seedlings are small during overwintering, the vegetative growth period is short, the accumulated nutrients are relatively reduced, cold resistance decreases, and the plants are prone to freezing damage, resulting in small bulbs and a reduced number of cloves, which likewise induces secondary growth in garlic. After sowing, cover with soil 1.5-2 cm, then water. The plot should be watered thoroughly and sufficiently, without missing a single plant, applying 100 cubic meters of water per mu. This not only meets the needs of garlic planting but also controls the occurrence of abnormal phenomena in garlic.