春天来了，一些土传病害比较严重。因为冬天温度低，植物本身的代谢比较慢，那个时候，即使根系出现问题，表现也不会很突出，再加上冬季气温比较低，病菌发展速度较慢。但是春天到来后，随着气温升高，棚室地温也会升高，土传病害就会表现的严重起来。
Spring has come, and some soil-borne diseases are more serious. Because of the low temperature in winter, the metabolism of plant itself is relatively slow. At that time, even if there are root problems, the performance will not be very prominent, coupled with the low temperature in winter, the growth rate of pathogens is slower. But after the arrival of spring, with the increase of temperature, the ground temperature of shed will also rise, and soil-borne diseases will become serious.
比如，我们知道的枯萎病、根腐病，温度在20度以上时发展速度比较快。深冬期土壤温度达不到20度以上，即使有发病植株，表现也不明显。但是春季温度升高、光照增强，地上部生长加快，同时病菌发展速度也加快，造成大棚死棵出现反弹现象，死棵比冬天更严重。
For example, we know that Fusarium Wilt and root rot disease develop faster when the temperature is above 20 degrees. In deep winter, soil temperature is less than 20 degrees, even if there are diseased plants, the performance is not obvious. However, with the increase of temperature and illumination in spring, the growth of the above-ground parts is accelerated, and the development of pathogens is also accelerated, resulting in the rebound of dead trees in greenhouses, which is more serious than that in winter.