Last week, I received a call from farmers in Xiaotan Township. They were worried because they noticed brown spots on the leaf sheaths of their wheat seedlings while sowing. They asked if it was a disease and how to treat it. After our station's technicians gathered more details, we quickly reached out to plant protection experts from the County Agriculture Bureau, including Senior Agronomist Miao Lianhe and Leader of the County Agricultural Station, Senior Agronomist Guo Peizong. Together, we visited the affected wheat fields to investigate the issue.
In Shilipu Village, one of the farmers, Mr. Li, was visibly anxious. As soon as we arrived, he led us to the middle of his field and bent down to pull up a few wheat seedlings. "Look, look! This is the problem," he said, clearly worried. After carefully examining the seedlings, we confirmed that the issue was wheat sheath blight.
According to Guo Peizong, the pathogen primarily infects the roots and base of the wheat stems, causing symptoms like rotting buds, dead seedlings, weak stalks, and even lodging. The disease can affect over 30% of the crop if left unchecked.
Miao Lianhe explained that infected seedlings show gray-brown spots on the leaf sheaths during the third or fourth leaf stage. These spots can spread across the entire sheath, making the leaves dark green and water-soaked. As the disease progresses, the base of the wheat stem develops oval, dark green, water-soaked lesions. Over time, these turn into grayish-brown centers with dark brown edges. When the lesions merge, the leaf sheaths appear mottled with streaks—this is known as "flower stalks," a classic sign of sheath blight. In severe cases, the plants may not produce ears properly, leading to dry booting or thin, dry white spikes. Even less severely affected plants are prone to lodging due to weakened stalks, which ultimately reduces yield.
Guo Peizong added that the timing of last year’s wheat planting and the unusually warm November weather created favorable conditions for the disease. Then, the rapid temperature rise in mid-February this year accelerated its development. A recent survey showed an average disease rate of 11.5% in Yanjin County, with some areas reaching 38%. With temperatures rising further in March, there is likely to be a peak in infections. Therefore, it’s crucial to take action before March 25 to control the disease effectively.
To manage wheat sheath blight, Miao Lianhe recommended two effective treatments: First, apply 100–150 ml of 5% Jinggangmycin per acre, mixed with 100–150 kg of water, and spray directly onto the base of the wheat plants. Second, use 25% Triadimefon WP at 20–25 grams per mu, or 12.5% propiconazole at 25–30 grams per mu, combined with 50 kg of water. Make sure to spray evenly over the wheat stems for best results.
By acting quickly and following these guidelines, farmers can significantly reduce the impact of wheat sheath blight and protect their harvest.
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