Rice physiological red blight can be controlled with raw gypsum powder

Rice physiological red blight often occurs in cold-waterlogged mountain valley fields and in paddy fields where organic green manure has not fully decomposed. This disease mostly occurs at the tillering stage of rice, showing as very little tillering, leaves turning yellow-brown, and tea-brown irregular spots on the first and second leaves from the base; some mistake it for leaf blast. When the rice hills are pulled up, the root system is yellow-brown, and in severe cases black; the seedlings do not grow, commonly called "fa qiu".

There are three main causes of physiological red blight: first, toxic substances such as hydrogen sulfide produced during the decomposition of green manure; second, the rust water in some cold-waterlogged fields contains toxic substances; third, the soil is too acidic, the soil is compacted, irrigation is too deep, and aeration is poor.

To control rice physiological red blight, in addition to rational fertilization and scientific water management, for mild cases broadcast 75-100 kg of burnt soil ash per mu, and for severe cases broadcast 10 kg of raw gypsum powder per mu; results can be seen after 8 days. This is because raw gypsum powder can decompose toxic substances in the soil, neutralize soil acidity, promote the formation of soil aggregates, and improve soil aeration, so the seedlings quickly grow new roots and resume normal growth.