Garlic growers sometimes encounter a peculiar issue where the fifth leaf of garlic develops into a tubular, onion-like structure, rather than expanding normally. This condition occurs in approximately 20% of cases, and in severe fields, it can affect over 30% of plants. The so-called "onion tubular leaf" is characterized by the fifth leaf failing to open properly, forming a tight tube that encases the sixth and seventh leaves as well as the garlic sprout. As a result, the inner leaves and sprouts become trapped, making it difficult for them to emerge naturally.
Normal garlic leaves are flat and elongated with a V-shaped cross-section, while the affected leaves are tightly curled, leaving only a small opening at the top. This phenomenon has been observed for the past five to six years, but its occurrence has increased significantly in the last two years.
Several factors contribute to this problem. Early sowing tends to increase the likelihood of onion-like leaves, while later planting reduces it. Additionally, rotating garlic varieties—such as switching between different regions in Shandong—can help minimize the issue, though it cannot completely eliminate it. Soil deficiencies, particularly a lack of boron, and excessive nitrogen fertilizer application are also associated with this condition.
Currently, there is no effective treatment or rescue method available. The only practical solution is manual intervention. Growers can use a large sewing needle to carefully insert it from the bottom of the tubular leaf, ensuring not to damage the garlic sprout inside. The needle is then moved parallel along the leaf, helping to peel back the tube and allow the inner leaves and sprout to emerge. This process, although time-consuming, can reduce crop losses and improve plant development.
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