How to prevent garlic clove degradation and leaf regrowth

When garlic grows to a certain stage, the scale buds begin to differentiate, the leaves degenerate, and the scale buds gradually form garlic cloves; the scales outside the degenerated scale buds form the outer skin of the garlic cloves. This is the general pattern of normal garlic growth.

At the same time the garlic scape emerges, a ring of small garlic leaves grows around the scape, with 5-7 small leaves growing around the scape. These small leaves are a long new leaf that the outer skin of the new garlic clove sends out along the scape, while the growing point of the new garlic clove has not sprouted. This is called the garlic degenerated leaf regrowth phenomenon, sometimes called the secondary growth phenomenon, also known as horsetail garlic. This phenomenon is the regrowth of degenerated garlic leaves when stimulated by external conditions - an atavism phenomenon. It does not belong to "secondary differentiation," because it is a leaf grown from the outer skin of the garlic clove, while the new garlic clove has not sprouted. This leaf emergence phenomenon has a relatively large impact on garlic scape yield, generally reducing it by 30-40%; it has a relatively small impact on garlic bulb yield, generally reducing it by 10-20%.

Causes:

Related to sowing date. In the northern marginal region, garlic sown before October 10 has a high leaf emergence rate, garlic sown after October 10 is less affected, and garlic sown at the end of October basically shows no leaf emergence phenomenon.

Related to plastic film mulching. Practice has proven that wherever plastic film mulching is used, the leaf emergence rate is high, and where there is no mulching, the leaf emergence rate is low or there is no leaf emergence. For garlic sown before October 10 and covered with plastic film, the leaf emergence rate is about 98%.

Related to the amount of nitrogen fertilizer applied. Where the base fertilizer applies 50 kg/mu or more of urea or 150 kg/mu or more of nitrogen, phosphorus, and potassium compound fertilizer, the leaf emergence rate is high, while where the base fertilizer applies less nitrogen, the leaf emergence rate is low.

Related to variety. Red-skin garlic has a high leaf emergence rate, white-skin garlic has a low leaf emergence rate, and early-scape garlic (Ershuizao) basically has no leaf emergence phenomenon (in individual plots it accounts for only 2-3%) leaf phenomenon.

Related to climate. For the same red-skin garlic, compared with 1996, with the same fertilization, sowing at the same time, and the same plastic film mulching, 1996 basically had no leaf emergence phenomenon, while 1997 commonly saw leaf emergence. The autumn and winter of 1997 were relatively warm. The current impression is that warm winters are the main cause of garlic degenerated leaf regrowth.

Preventive countermeasures:

The garlic degenerated leaf regrowth phenomenon is the result of the combined action of many complex causes. If 1-2 factors are absent, it is possible to avoid or reduce the occurrence of this phenomenon. Therefore, the following countermeasures should be adopted in cultivation:

Control the sowing date. In the Shandong region, open-field cultivation can be sown in early October, and plastic film mulching cultivation can be sown in mid-October. In general areas, sowing can be appropriately delayed by 5-7 days.

Balanced fertilization and loosening the soil. The base fertilizer should be mainly organic fertilizer, chemical fertilizers should be appropriate, and nitrogen, phosphorus, and potassium fertilizers should be applied in proportional combination. Before sowing, make the soil at a depth of 50 cm loose and permeable, to promote root development into deeper layers and absorb phosphorus and potassium nutrients from deep soil.