人常说:“水是小麦的命,又是小麦的病。”小麦生长发育过程离不开水,但水分过多又会造成湿害。江汉平原和长江中下游其它麦区,开春后的3到5月正是多雨季节,常常有30～40多天降雨,最多达50天以上。过量的降雨,使土壤中水多气少,水、气失去平衡不仅使小麦根系活力衰退,呼吸困难,养分吸收受阻,甚至植株枯死,而且由于田间湿度增大,使田间小气候恶化,小麦白粉病、纹枯病、锈病暴发,赤霉病流行,致使小麦籽粒灌浆不饱,千粒重降低,产量下降,麦质差。湿害是南方麦区难以高产的重要原因。防御小麦湿害的主要措施: People often say: “Water is the life of wheat, but also wheat disease.” Wheat growth and development can not be separated from the water, but too much moisture can cause moisture damage. The Jianghan Plain and other wheat areas in the middle and lower reaches of the Yangtze River are rainy seasons from March to May after the spring and often have more than 30 to 40 days of rainfall up to 50 days or more. Excessive rainfall, soil less water and more gas, water and gas out of balance not only the root activity of wheat recession, breathing difficulties, nutrient absorption blocked, and even dead plants, but also due to increased field humidity, the field microclimate deterioration, wheat powdery mildew , Sheath blight, rust outbreak, the prevalence of Fusarium head blight, resulting in insufficient grain filling of wheat, reduced 1000-grain weight, decreased yield and poor quality of wheat. Wet damage is an important reason for the high yield of wheat in the south. The main measures to prevent wheat damaging: