Symptom Identification and Control Methods for Rice Phytotoxicity
Rice is the national staple food, and half of the country's population must eat rice every day. During cultivation, rice will inevitably encounter many pests and diseases, and when pests and diseases occur, pesticides must be sprayed for control. However, if pesticides are not used properly, they can cause phytotoxicity in rice, and the harm of phytotoxicity is no less than that of pests and diseases. So what are the symptoms of phytotoxicity? How should it be controlled? Let's take a look together below.
1. Disease Symptoms
Rice phytotoxicity generally has two types, chronic and acute. The characteristics of chronic phytotoxicity in the early stage are not very obvious, and the development speed is relatively slow. Rice generally shows slowed growth, reduced tillering and fewer grains, affecting rice yield. Acute phytotoxicity begins to develop within 1-2 days after spraying pesticides and produces a series of symptoms, as detailed below.
(1) Spots appear: When rice is affected by phytotoxicity, yellow or brown spots appear on the rice leaves, causing rice growth to be hindered.
(2) Rice wilting: When too much herbicide is used, the entire rice plant will wilt. No herbicide should be sprayed during the rice seedling stage.
(3) Growth stops: Rice affected by phytotoxicity will have its growth and development hindered, and its growth rate will decrease, usually appearing together with spots.
(4) Malformed growth: Phytotoxicity can also cause deformities in the leaves and roots of rice, with leaves forming curled leaves and roots swelling.
2. Causes of Onset
Many farmers, for the sake of convenience, mix all kinds of pesticides together when spraying, resulting in excessively high pesticide concentration. The rice growing period is also in summer, and high-temperature weather is extremely favorable to the occurrence of phytotoxicity. Or pesticides are used incorrectly, which is a mistake that many farmers are very prone to making. Many people do not look carefully when buying pesticides. Some pesticides are suitable for crops such as vegetables and fruits, but are used on rice, causing rice to be unable to adapt and resulting in phytotoxicity. There is also misjudgment: some farmers cannot accurately judge the diseases affecting rice and do not treat the root cause. Not only do they fail to solve the disease, but they also trigger phytotoxicity.
3. Control Methods
If it is found that many spots have appeared on the rice and it is close to turning yellow and withered, or the whole plant is close to withering, all the water in the field should be drained immediately, part of it replaced with fresh water, and some fertilizer added to supplement the nutrients lost due to pesticides and restore the normal growth of the rice. If herbicide was mistakenly sprayed, a large amount of clean water should be sprayed in the field immediately to wash off the herbicide on the rice, repeatedly changing the water to reduce the pesticide concentration in the field.
In fact, the occurrence rate of rice phytotoxicity is even higher than that of rice diseases, because many people frequently spray large amounts of pesticides to prevent rice from being invaded by pests and diseases. But they do not pay attention to the type and amount of pesticides. Excessive concentration will cause irreparable harm to rice, so when spraying pesticides, it must be based on the type of rice disease for prevention, and it must not be done blindly.