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Comprehensive prevention of corn rough dwarf
Maize rough dwarf disease is a viral infection caused by the Maize rough dwarf virus (MRDV). In recent years, the disease has shown a noticeable increase in certain regions of our province, becoming one of the most significant threats to corn production. This disease not only reduces yield but also affects the overall quality of the crop, making it a critical issue for farmers and agricultural authorities.
The symptoms of the disease typically appear after infection. Infected plants show curled and dark green leaves, which become thick, hard, and brittle. Clusters of leaves form, and waxy white stripes may appear along the back of the leaf veins. In severe cases, seedlings may die or grow weakly. During the 3–5 leaf stage, the upper part of the plant becomes stunted, with clustered, bluish-green leaves that often fail to tassel or produce ears, leading to significant yield loss. In later stages, such as 5–7 leaves, the plants are still stunted, with dark green leaves, but they may still tassel. However, their economic value is greatly reduced. In rare cases, infected plants may develop short tassels that cannot properly form ears, or female ears may lack silks, which is a sign of late infection.
The occurrence of this disease depends on three key factors: the presence of the virus, the vector (such as the Small Brown Planthopper), and the susceptibility of the maize variety. When these elements combine—especially when virus levels are high, vectors are abundant, and susceptible varieties are planted—the disease can spread rapidly. The population dynamics of the vector, climate conditions, and the growth stage of the host plant all play a role in determining the severity of the outbreak.
First, the amount of virus present in the environment is crucial. Grasses and weeds serve as primary hosts for the virus, so fields with poor weed management tend to have higher infection rates. For example, wheat fields with a high incidence of wheat dwarf virus often lead to increased MRDV transmission through the same vector, SBPH.
Second, the sowing date of corn and the presence of weeds significantly influence disease development. Early-sown corn fields, especially those adjacent to weedy areas, orchards, or roadsides, are more vulnerable. The early growth stages of corn, particularly from emergence to the 7-leaf stage, are the most susceptible to infection. The earlier the infection occurs, the more severe the damage tends to be.
Third, weather conditions also affect the disease cycle. Warmer autumns and winters have led to increased survival of insect vectors like Laodelphax striatellus, resulting in higher populations of the virus-carrying insects. This has contributed to the rising incidence of the disease in recent years.
Lastly, the resistance level of the maize varieties plays a vital role. Most currently cultivated varieties are highly susceptible, with very few resistant or highly resistant options available. This makes the crop more vulnerable to outbreaks once the vector population increases.
To manage this disease effectively, an integrated approach is necessary. This includes using resistant varieties, adjusting planting dates to avoid peak vector activity, removing weeds to reduce virus sources, and applying chemical controls when needed. Farmers should prioritize field hygiene, remove infected plants, and implement proper irrigation and fertilization practices to promote healthy growth and reduce disease risk.
Chemical control measures, such as seed treatments with insecticides or foliar sprays during the seedling stage, can help suppress vector populations and reduce virus transmission. Spraying with products like 10% imidacloprid or 20% virus A WP has proven effective in controlling the disease when applied correctly.
In summary, preventing and managing Maize rough dwarf disease requires a combination of cultural, biological, and chemical strategies. By understanding the disease's life cycle and adopting proactive measures, farmers can significantly reduce its impact on corn yields and ensure more sustainable production.