What control measures should be taken when pathological changes occur in garlic scapes during storage?

Abnormal changes of the scape tip

1. Browning of the scape tip

(1) Symptoms The scape tip changes from yellow-green to yellow-brown or dark brown, dehydrates and shrinks into a thin flake-like form, is prone to decay and easily infected by mold, and loses its toughness; dry-affected ones break easily, and wet-affected ones rot easily and are infected by mold.

(2) Causes The tissues of the scape tip undergo physiological aging and death, and lose water and shrink. High temperature and high oxygen promote browning, and high humidity aggravates the degree of browning.

(3) Control Harvest at the proper time, and strictly prevent high temperature, air-drying, or smothering during harvest and transport; maintain a suitable low temperature and long-term stability in the storage room; maintain sufficient carbon dioxide accumulation before storage; tie the bag opening tightly, prevent bag leakage, and shorten the time the bag opening is left open during oxygen supply.

2. Moldiness of the scape tip

(1) Symptoms The scape tip turns brown and damp, and irregular black downy spots and white cotton-like masses grow on the surface; as time passes, the mold spots expand and merge, and the scape tip rots.

(2) Causes Mold spores infect the surface tissues of the scape tip, producing black downy spots, and the mycelium grows and develops to form cotton-like masses. The mold secretes hydrolytic enzymes and toxins, causing the tissues of the scape tip to disintegrate and rot.

(3) Control Before storage, cut off the severely browned and rotten parts of the scape tip; maintain a suitable low temperature and long-term stability in the storage room; during storage, maintain sufficient carbon dioxide accumulation to inhibit the growth and development of mold; prevent high-oxygen environments caused by factors such as bag leakage, loose bag openings, or different loading amounts; eliminate as much as possible the transmission routes of mold through wind, water flow, and hands; adopt necessary disinfection measures to reduce sources of inoculum.

Abnormal changes of the scape bulb

1. Rust spots on the scape bulb

(1) Symptoms On the epidermis of the bracts there are irregular small raised reddish-brown spots with a central pimple-like point. These bracts are thicker and harder than normal bracts.

(2) Causes Disease spots from the field growth period.

(3) Control Strictly select and prevent garlic scapes with rust spots from entering storage; strengthen management of the storage environment to prevent deterioration of rust-spotted scape bulbs; store separately and take out of storage early.

2. Swelling of the scape bulb

(1) Symptoms The bracts of the garlic scape change from thick to thin, from fresh green to yellow-brown, and the whole swells into a garlic-head shape; in severe cases the bracts split, the aerial bulbils scatter, and after deterioration it becomes a water-rotted scape bulb.

(2) Causes High temperature and high oxygen strengthen the respiration of garlic scapes and accelerate physiological and biochemical processes. Swelling of the scape bulb is the result of nutrients and water in the scape stalk transferring to the scape bulb (aerial bulbils).

(3) Control Harvest at the proper time and shorten the harvest and transport time as much as possible; the work of selection, processing, precooling, and bagging should emphasize the word "fast"; maintain a suitable low temperature and long-term stability in the storage room; tie the bag opening tightly, prevent bag leakage, and shorten the time the bag opening is left open during oxygen supply; in the early storage period, pay attention to giving play to the role of carbon dioxide in inhibiting the physiological activities of garlic scapes.

3. Yellow wilt of the scape bulb

(1) Symptoms The aerial bulbils stop growing, and the bracts appear yellow or yellow-brown. The epidermis gradually forms dehydrated and shrunken patches from top to bottom, and the tissues of the scape bulb yellow-wilt and die.

(2) Causes Because the stalk and base parts of the garlic scape have already aged, the transport and supply of nutrients and water needed for the growth of the scape bulb are insufficient, causing the scape bulb to lose green and turn yellow, stop developing, and die naturally.

(3) Control Harvest at the proper time, shorten the time of harvest, transport, selection, and processing, and prevent early aging of garlic scapes; do not store seriously aged garlic scapes; for slightly aged garlic scapes, all aged parts must be cut off before storage, leaving no hidden trouble; maintain a suitable low temperature and long-term stability in the storage room; in the early storage period, oxygen supply should be appropriate and not too high, and especially prevent bag leakage and long-term high-oxygen environments easily caused by bag openings that are too loose.

4. Gray death of the scape bulb

(1) Symptoms The aerial bulbils of the garlic scape stop developing or the growing point dies. The bracts appear gray-green or gray-white, and there are flake-like dead spots with longitudinal veins extending from the scape tip; after deterioration they become boiled-looking.

(2) Causes High temperature plus oxygen deficiency, or the effect of long-term high carbon dioxide at suitable temperature, can cause disorders in the physiological and biochemical processes of the scape bulb, accumulate toxic substances in cells or increase cell permeability, and cause cell death. It is a typical physiological disease.

(3) Control Strictly prevent garlic scapes that have been smothered and heat-damaged from entering storage; the loading amount should be appropriate, and for garlic scapes from different producing areas and of different quality, the low-limit indicators for oxygen supply should be determined separately, and the range of upward adjustment time in the middle and later periods should be truly mastered; during oxygen supply, the restoration of oxygen should be sufficient and the residual amount of carbon dioxide should be small; great attention should be paid to the changing patterns of high carbon dioxide accumulation in each cycle to prevent harm caused by high carbon dioxide.

5. Mold rot of the scape bulb

(1) Symptoms Local or most tissues of the scape bulb become necrotic and grow white cotton-thread-like material; in severe cases the scape bulbs connect with one another, forming white cotton-like masses, the bracts rot, and they easily separate from the scape stalk at the stem disc.

(2) Causes After yellow wilt, gray death, or other damage occurs in the scape bulb, mold infects it and grows, develops, and spreads. The hydrolytic enzymes and toxins secreted by the mold cause tissue cell death and body rot.

(3) Control Strictly select and process, and do not let garlic scapes with dead scape bulbs and rotten scape tips enter storage; create a good storage environment and keep the whole garlic scape intact and healthy; maintain a suitable low temperature in the storage room and make full use of sufficient carbon dioxide accumulation to inhibit the growth and development of mold; prevent high-oxygen environments caused by reasons such as bag leakage and loose bag openings; strive to reduce the possibility of transmission by wind, water flow, and hands; adopt necessary disinfection and sterilization measures to reduce sources of inoculum.

Abnormal changes of the scape stalk