Causes of Yellowing Leaves in Rice Seedlings and How to Prevent and Treat It

It is now the peak growing season for rice, and many farmers have noticed that their rice has turned yellow overnight. We need to analyze whether it is happening in only a few individual plants or across the board, or whether it was caused by some chemical that was applied. So what causes yellowing leaves in rice seedlings? How do you treat it effectively? How do you prevent and control it?

I. Causes of yellowing leaves and dried leaf tips in rice seedlings

During the growth period of rice seedlings, the leaves are relatively tender and have poor stress resistance and disease resistance. Combined with changeable weather, improper management can lead to problems such as yellow leaves and dried tips in the seedlings.

1. Caused by nutrient deficiency

This is especially likely when the seedbed has not been earthed up or was prepared with nutrient soil. It generally becomes more obvious after the seedlings reach the 2.5-3 leaf stage, and yellowing seedlings with dried leaf tips and similar symptoms basically appear across the board.

2. Caused by improper management

When field temperatures are too high or too low, or humidity is too high or water is insufficient, it can also lead to poor nutrition, causing leaves to turn yellow, have dried tips, or turn white or brown, and the problem will spread downward and outward. Improper ventilation of the leaves can also cause dried tips; when temperature discomfort is the cause, it is generally more obvious at the air vents.

3. Caused by pests and diseases

Large temperature differences and improper management can cause damping-off, bacterial wilt and other diseases, and damping-off in particular will cause seedlings to turn yellow, have dried tips and die, with death occurring in multiple spots and patches. Damage by thrips can cause leaves to curl lengthwise and dry up, looking like fire from a distance, and insects can be seen when the curled leaves are opened.

4. Caused by improper fertilization or pesticide application

When supplementing fertilizer through the leaves or controlling pests and diseases, if the concentration is too high, or the spray is uneven, or the seedlings are not rinsed promptly after spraying fertilizer, it can easily cause leaf burn. Symptoms such as chlorosis and yellowing, or dried leaf tips, will appear.

II. How to treat it effectively

1. For nutrient deficiency

Be sure to promptly choose a high-nitrogen water-soluble fertilizer, or supplement through the leaves with urea + monopotassium phosphate to relieve it.

2. For improper management

Be sure to ventilate in good time and remove the film to harden the seedlings. The seedling bed should not be excessively short of water, nor should it be watered too much. In addition to strengthening routine management, after the problem occurs you can promptly spray Bihu, or brassinolide + seaweed acid, or Meizhouxing + monopotassium phosphate to relieve it. This enhances stress resistance and disease resistance, and promotes rapid recovery.

3. For pests and diseases

For damping-off, promptly spray jia shuang fu, or Ruimiaooqing and similar chemicals + rooting agent, or Meizhouxing, or seaweed acid for control. For thrips, you can spray clothianidin, or imidacloprid, or carbosulfan and similar products for control.

4. For improper fertilization or pesticide application

In addition to promptly strengthening water and fertilizer management, promptly spray Bihu on the leaves, or brassinolide + seaweed acid or Meizhouxing, to help relieve the phytotoxicity and quickly restore normal growth.

III. How to prevent and control it

1. Spraying organophosphorus pesticides such as trichlorfon, profenofos, chlorpyrifos, triazophos and phoxim in rice fields may cause phytotoxicity to rice when the dosage is too large or the application concentration is too high, producing small brown spots on the leaves; phytotoxicity is even more likely when a mist sprayer is used for application during high temperatures.

2. Yellowing leaf tips in rice may be caused by potassium deficiency, and spraying nitrogen fertilizers such as urea will worsen the potassium deficiency symptoms. If the healthy parts of the rice leaves do not show yellowing caused by nitrogen deficiency, do not spray urea. If the healthy parts of the rice leaves do show yellowing, you can mix urea with monopotassium phosphate and spray, using 500 grams of urea and 100——150 grams of monopotassium phosphate per 50 kilograms of water.

3. The concentration of monopotassium phosphate sprayed in rice fields must not be too high, otherwise it may harm the rice seedlings; generally spray at a concentration of 0.2%——0.3%.

4. For rice varieties that show symptoms of red or yellow leaf tips, fertilizer and water management should be strengthened when growing that variety, to avoid long-term waterlogging in the field and root suffocation.