How to distinguish between element deficiency and pathological diseases in other places?

In production practice, element deficiency caused by lack of nutrition in plants is often confused with pathological diseases caused by pathogenic microorganisms, especially with symptoms caused by viruses and nematodes, because most of these symptoms are mosaic, yellowing and poor growth.

So, how to distinguish between element deficiency and pathogen infection? Generally speaking, we can start from three aspects: ① disease center. General pathological diseases have obvious centers, and pathogenic bacteria can be found. If you diagnose whether there is bacterial blight in rice, you can check whether there is "bacterial concentration" secretion at the leaf edge or tip of rice in the morning. If the "bacterial concentration" overflows and turns into caviar after drying, drugs such as "killing people" should be used to prevent it; Element deficiency has no heart disease, mostly sporadic; ② Soil type and nitrogen application level. Usually, pathological diseases have no obvious relationship with soil types, but are closely related to nitrogen application level, and most of them occur in fertile fields; Element deficiency is closely related to soil types, which can occur in soils with different fertility levels, but most of them occur in poor soils, such as calcareous soils lacking zinc, iron and manganese, and acidic soils lacking molybdenum; ③ Weather conditions. Pathological diseases mostly occur in rainy and humid weather, and rarely occur in drought. However, element deficiency often occurs in low temperature or long-term dry soil. For example, when early rice is transplanted at low temperature, it is easy to lack phosphorus and zinc, and when the soil is dry, it is easy to cause element deficiency such as boron deficiency in rapeseed and calcium deficiency in Chinese cabbage.