Corn is a vital food crop that plays a crucial role in global food security. Understanding the diseases that affect corn and implementing effective control measures are essential for ensuring high and stable yields. Proper disease management not only protects the crop but also supports sustainable agricultural practices.
One of the most common diseases affecting corn is **maize big spot disease**, which primarily targets the leaves. In severe cases, it can also damage the sheaths and husks. The infection typically starts from the lower leaves and progresses upward. Initially, small, oval-shaped yellow or grayish-blue water-soaked spots appear. Over time, these lesions expand along the leaf veins, forming stripe-like patterns. As the disease advances, the spots turn dark brown or yellow-brown. To manage this disease, farmers should choose resistant varieties, practice crop rotation, and promptly remove and destroy infected plant parts. Fungicides such as 50% carbendazim WP, 50% amidicarb WP, or 40% kresoxim-methyl EC diluted to 500 times can be applied at the early stage, with applications repeated every 10 days for 2–3 times. Each application requires about 75–100 kg of solution per mu (667 square meters).
Another common issue is **corn leaf spot**, which mainly affects the leaves, though it can occasionally occur on the stalks, husks, and ears. Lesions are usually oval, spindle-shaped, or rectangular, appearing gray-brown or tan. Control strategies include using resistant varieties, removing and destroying diseased leaves, and applying fungicides like 50% diuron 300–500 times dilution, 75% chlorothalonil 300–500 times, or 40% mancozeb 500–1000 times. Other options include 40% formamide, 907 zinc, or other 500 times solutions, along with 1500 times thiophanate methyl spray.
**Corn tumor smut** is another serious disease that causes nodules to form near the base of the plant. In severe cases, young seedlings may die. Infected tissues, including roots, leaves, stems, and ears, can develop clusters of bacterial masses after the plant has jointed. Control methods include selecting resistant varieties, removing and burning infected plants, and applying herbicides before the corn emerges.
**Corn smut**, also known as "common smut," causes stunted growth, shortened internodes, and dark green or yellow-white striped leaves. After tasseling, the ears are often destroyed and replaced by black, powdery spores. When mature, the infected ears open and release spores with long filaments. To prevent this disease, farmers should use resistant varieties, rotate crops, remove infected plants, and apply well-decomposed organic fertilizers. Seed treatment with 0.2–0.3% triazole fungicides or 25% triadimefon wettable powder mixed with an adhesive paste is also recommended before planting.
These disease management practices are critical for maintaining healthy corn production and minimizing yield losses. By combining cultural, biological, and chemical control methods, farmers can effectively protect their crops and ensure sustainable agricultural development.
Author: Agricultural Technology Station, Dongdu Town, Xindu City
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