What causes yellowing rice leaf tips

Rice is the largest food crop in China, but at present, rice-growing areas across the country generally have some seedling problems, such as diseased seedlings and weak seedlings. Among these, the most common is yellow tips on rice, so what problem are yellow rice tips?

1. What problem are yellow rice tips?

Yellow rice tips are rice damping-off disease. This disease is a seedling-stage disease caused by the reduced disease resistance of seedlings under the influence of various adverse environmental factors, which allows Fusarium, Rhizoctonia solani and rice rot fungi, among others, to invade while the plants are weakened.

2. Symptoms of rice damping-off disease

Rice damping-off disease is one of the main diseases of dry-raised rice seedlings. Its main causes are excessively low temperature, excessively large temperature differences, alkaline soil, insufficient light causing thin and weak seedlings, and excessive sowing rate. The main field symptoms are seedling wilting after emergence, being easy to break when pulled, rotting at the base of the stem, a rotten pear smell, and whole patches dying in more severely affected areas. Diseased plants often have red mold-like growth at the base.

3. Prevention and control

1. Carefully select seeds and sun-dry seeds. Improve sprouting techniques, prevent seed injury, and improve seed vitality and disease resistance.

2. Sow at the appropriate time, and do not sow too densely. Sowing should be done when the temperature steadily passes 6°C, and do not blindly rush to sow early. Theoretically, the sowing density should be 300 g/m2. However, in actual production, farmers often increase the sowing rate in order to save production costs such as agricultural film, and considering factors such as emergence rate and the use of rice transplanters. Even so, the sowing rate must absolutely not exceed 500 g/m.

3. Seedbed management. Do a good job in cold prevention, heat preservation, ventilation, seedling hardening and other steps to improve seedling disease resistance and prevent and reduce the occurrence of damping-off disease and bakanae disease.

4. Strengthen field management. Do a good job in cold prevention, heat preservation, ventilation and seedling hardening, and achieve early protection (heat preservation before emergence), mid-stage control (temperature control from emergence to the 3-leaf stage), and later hardening (temperature adjustment from the 3-leaf stage to before transplanting). Advocate sparse transplanting and early seedling raising, and control temperature and humidity to prevent excessive growth. During the 1-leaf-1-heart stage, maintain a temperature of 25-30°C and water as little as possible. After the 2nd leaf stage, the seedlings must gradually adapt to cold conditions. During the 3-leaf-1-heart stage, the temperature should not exceed 25°C, and the soil moisture should be sufficient but not excessively wet. After the 3-leaf stage, the film should be uncovered during the day for ventilation and hardening. At night, if there is no frost, it is best to also uncover the film so the seedlings can endure low temperatures. In this way, strong seedlings with high cold resistance can be cultivated.

Yellow rice tips are a relatively common problem. When planting, choose high-quality rice seeds and carry out good field management to effectively prevent it.