Maize Genomics and Genetics 2025, Vol.16, No.3, 149-166 http://cropscipublisher.com/index.php/mgg 162 severe cases. This experimental field also monitored signs of corn borer larvae before and after tasseling, and timely applied pesticides in mid-May for prevention and control. However, corn borers overlap generations and are highly hidden, making prevention and control difficult, requiring multiple continuous medications and field management. The lack of prevention and control awareness and measures by some growers is a weak link in the current green prevention and control of corn borers. The residual insect sources in the field are prone to re-infection in the next season, posing a long-term threat to the production of fresh corn. In terms of diseases, corn leaf spot and small leaf spot are two leaf diseases that are prone to prevalence in local high temperature and high humidity seasons, and they also pose a threat to the yield and quality of fresh corn. Corn leaf spot generally occurs after corn leaf tasseling, and the environmental conditions suitable for the disease are a temperature of 20 ℃ to 25 ℃ and a relative humidity of more than 90%. When the disease occurs, large water-soaked gray-brown patches first appear on the middle and lower leaves of corn, and then spread upward. In severe cases, large areas of leaves of the entire plant die. Corn leaf spot prefers a warm and humid environment, and is very likely to break out in a rainy climate of 26 ℃~29 ℃. Corn leaf spot can occur throughout the growth period of corn, especially after the tassels emerge, and is most harmful. It manifests as small concentric rings with reddish-brown edges on the ears, leaves and sheaths. When the humidity is high, a black mold layer grows on the lesions (Bhat and Anwar, 2017). Large-scale outbreaks of these two leaf spot diseases will significantly reduce the functional leaf area of corn, premature plant decline, shorten the filling period and poor grain development. In the field, it is often seen that the female ears of infected plants are bald or the grains are shriveled, the ear shape becomes smaller, and the fruiting is poor, which ultimately leads to a decline in the quality of commercial ears and a loss of yield. In particular, small leaf spot can break out in the rainy summer season. If not prevented and controlled in time, it will seriously threaten the high and stable yield of corn (Rizzardi et al., 2022). Corn sheath blight and rough dwarf disease also occur sporadically in the test area. Once the environment is suitable, they may also break out, which will have a potential impact on corn growth and ear quality. The prevalence of diseases will reduce the fullness and edible quality of fresh corn kernels, increase the risk of mildew and toxins, and is not conducive to the commodity value of fresh corn and the taste experience of consumers. In terms of pest and disease control, the experiment also exposed some difficulties and weak links. First, fresh corn aims to put tender ears on the market, and has high requirements for pesticide residues, which limits the frequency and dosage of chemical pesticides and increases the difficulty of green pest and disease control. Pests such as corn borers need to be prevented as the main method, such as removing field stumps in winter to reduce overwintering insect sources and applying pesticides in time during the heart leaf stage. However, in actual promotion, it is often difficult for small farmers to take unified actions in a timely manner due to their scattered operations. Winter straw treatment and drug use during the critical period are sometimes not in place, making it difficult to completely reduce the insect population base. Secondly, for diseases such as large spot disease and small spot disease, it is required to select disease-resistant varieties, balance fertilization to improve disease resistance, and spray the right pesticides in time for continuous prevention and control 2 to 3 times at the early stage of the disease. However, grassroots growers are often constrained by costs and insufficient technical guidance, and often fail to implement multiple sprayings or completely remove diseased residues according to regulations, leaving room for the spread of diseases. Furthermore, some diseases such as corn dwarf disease currently lack specific pesticides, and can only be reduced by avoiding sowing during the peak period of virus-transmitting insects and controlling vector insects. Preventive measures such as these all show that in the large-scale demonstration and promotion of fresh corn, the high incidence of pests and diseases requires a more complete unified prevention and control mechanism and technical training support. The current prevention and control work still has weak links, which directly threatens the appearance quality and internal flavor safety of fresh corn products. 6.3 Limitations on demonstration and promotion due to issues in sowing and management timing Whether the planting rhythm and field management timing of fresh corn production are reasonable has an important impact on the effect of new variety demonstration and promotion. In the actual promotion process of this study, it was found that factors such as seasonal climate and labor resources led to certain problems in sowing
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