Recently, I received a call from farmers in Xiaotan Township. They mentioned that while sowing wheat, they noticed brown spots on the leaf sheaths near the surface of the young plants. Concerned about the health of their crops, they asked whether this was a disease and how to manage 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 Director Guo Peizong of the County Agricultural Station, to visit the affected wheat fields.
In Shilipu Village, located in Xiaotan Township, farmer Li was anxiously waiting by his field. As soon as we arrived, he led us to the center of the field and bent down to pull up a few wheat seedlings. He said with concern, "Look, look! This is the problem. The leaves have streaks! It’s really worrying!" After carefully examining the samples, we confirmed that the issue was wheat sheath blight.
According to Guo Peizong, the pathogen causing wheat sheath blight primarily infects the roots and lower stems of wheat plants. This leads to symptoms such as rotting buds, dead seedlings, hollow stalks, rotten stems, lodging, dry booting, and dry white ears. In severe cases, the infection rate can exceed 30%, which significantly impacts yield and crop quality.
Miao Lianhe explained that infected wheat seedlings typically show gray-brown spots on the leaf sheaths from the third to fourth leaf stage. These spots can spread across the entire sheath, causing the leaves to appear dark green and water-soaked. As the disease progresses, the base of the wheat plant develops oval, dark green, water-soaked lesions. Over time, these lesions turn grayish-brown in the center and dark brown at the edges, forming an irregular, mottled pattern. When the lesions merge, the sheaths take on a streaked appearance, commonly referred to as "flower stalks." This is a classic symptom of sheath blight. In heavily affected fields, the plants may fail to produce ears, resulting in dry booting. Even when ears do form, the number of grains is often reduced, and the ears may be thin and weak, leading to dry white spikes. Plants with milder infections may still head normally but are prone to lodging due to weakened stems, ultimately reducing overall yield.
Guo Peizong added that the timing of wheat planting last year, combined with unusually high temperatures in November, created favorable conditions for the disease. Additionally, the rapid temperature increase since mid-February this year has further accelerated the development of wheat sheath blight. According to recent surveys, the average disease incidence in Yanjin County is 11.5%, with some areas reaching up to 38%. With temperatures continuing to rise in March, there is expected to be a peak in infection. Therefore, it is crucial to act quickly before March 25 to implement control measures.
Finally, Miao Lianhe provided specific recommendations for managing wheat sheath blight:
1. 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.
2. Alternatively, use 25% Triadimefon WP at 20–25 grams per mu, or 12.5% Propiconazole at 25–30 grams per mu, mixed with 50 kg of water and evenly sprayed over the wheat stems.
These steps are essential to prevent the spread of the disease and protect the yield of the upcoming harvest.
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