The primary pests affecting leafy vegetables include the peach aphid, radish aphid, cabbage aphid, and lettuce aphid. Among these, the peach aphid is the most widespread, not only damaging cruciferous crops but also affecting spinach, peppers, and eggplants. Radish aphids tend to infest varieties with less waxy surfaces, such as radishes and cabbages. Bletilla esculenta, which affects smooth, waxy cabbages and broccoli, typically shows symptoms like partial leaf curling, especially on cool days. Lettuce aphids, often identified by their red tubular appearance, are easily distinguishable when they damage lettuce plants.
The occurrence of rapeseed aphids is most favorable under dry weather conditions between 16–25°C. In Jiangyan District, infestations are more severe in early autumn and late spring, while occurrences are lower during winter and summer. Under good nutrient conditions and low population density, wingless aphids dominate. However, when nutrition is poor, a large number of winged aphids are produced, leading to rapid spread. These pests reproduce very quickly, with over 40 generations possible per year. Under ideal conditions, they can complete a life cycle in just 4 to 5 days. If farmers fail to implement timely control measures, infestations can lead to crop losses and the spread of viral diseases.
Controlling aphids in large-scale vegetable production requires several key strategies. First, regular field monitoring is essential, with early intervention before peak infestation periods. Spraying should be thorough, covering both the upper and lower leaf surfaces. A spray schedule of once every 5–7 days, repeated 2–3 times with intervals of 5–7 days, is recommended. Second, select insecticides with strong systemic absorption and dual contact/fumigant effects, such as 25% imidacloprid diluted 2000–3000 times, 10% imidacloprid at 3000–4000 times, 15% imidaclothiz 2000 times, 3% Mobipro 3000 times, 19% Kebu 2000–2500 times, or 50% Piperonyl butoxide at 1500 times. Third, use silver-gray mesh or plastic mulch to repel winged aphids from entering the fields. Finally, remove weeds both within and around the fields to reduce potential pest sources.
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