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Pest control program of late winter jujube
Late winter jujube trees are commonly affected by several diseases and pests. Among the main diseases are black spot disease, date rust disease, and jujube fruit shrinking disease. In terms of pests, the primary threats include hawthorn leafhoppers, green leafhoppers, and other similar insects.
Date rust, also known as jujube rust, mainly affects the leaves. Initially, small yellowish spots appear on the surface, which gradually become raised and irregular in shape. As the disease progresses, the spots break open and release yellow powder. On the upper side of the leaves, chlorotic spots develop, turning into tan-colored lesions. Eventually, the leaves dry up and fall prematurely. Severe cases can lead to early defoliation, causing the fruits to shrink, reducing sugar content, weakening the tree, and affecting both yield and quality. The disease typically begins in mid-July, peaks between August and September, and declines afterward. High humidity and heavy rainfall from July to August promote its spread, while drought years tend to see milder outbreaks. Trees in low-lying areas with dense foliage and damaged canopies are more prone to infection, whereas well-ventilated, high-lying orchards are less affected. To prevent it, proper drainage is essential during the rainy season to avoid excessive moisture. Spraying 25% Guanxin (a fungicide) at 5000–6000 times dilution mixed with soft water, two or three times in early July, is recommended. If there is frequent rain in August, another application of the same mixture should be made. This helps control the disease effectively.
Jujube fruit disease primarily affects the fruit, with symptoms progressing from halo formation, water-soaked spots, discoloration, to shriveling and falling. Infected fruits show yellowish, watery patches around the waist, with clear edges. These lesions later turn dark red and dull. Some fruits display light brown stripes along the stem, and the flesh becomes pale and spongy, eventually turning necrotic. The disease may be caused by fungi, bacteria, or a combination, and is often linked to pest damage or environmental stress like high temperatures and dry weather. Preventive measures include controlling pests such as green-legged ticks and using broad-spectrum fungicides that target both fungi and bacteria. Spraying 72% agricultural streptomycin at 2000–3000 times dilution, combined with nano-nano WP at 1000 times, every 10–15 days has shown good results. Recently, products like 80% Jinnai seawater dispersible granules have been introduced, offering cost-effective control when used at 800–1000 times dilution. Additionally, practices like rational fruit thinning, applying Galishi or calcium lactate during flowering, and managing weeds can help reduce mechanical injuries and improve overall tree health.
Black spot disease mainly affects the fruit, appearing when the jujubes are expanding and coloring. It starts with irregular yellow spots on the shoulders or base of the fruit, which gradually deepen into reddish-brown or dark brown areas. The flesh turns yellow, then brown, and eventually becomes gray or black, with a spongy, bitter texture. In humid conditions, black spots may develop on the surface. Prevention involves maintaining strong, healthy trees. When trees are weak or suffer from iron deficiency, the disease tends to be more severe. Applying imported green fertilizer at 6000 times dilution, or using Sterpool trace element fertilizer at 6000 times, along with amino acid mixtures at 200–300 times, can help restore tree vigor. During the fruit expansion period, spraying 65% Pud-Kin wettable powder at 600–800 times dilution mixed with soft water every 15–20 days is effective for prevention. At the onset of the disease, applications of 50% Dove-Have suspending agent at 800–1000 times, or 70% Nano-Sweet WP at 1000 times, can help manage the condition effectively.