What is the reason for the yellowing of rice seedling leaves? How to govern effectively? How to prevent and cure?

Now it is the peak period of rice growth, and many farmers find that their rice turns yellow at night. We have to analyze whether it is caused by individual plants, or generally, or by what agents have been used, so what is the reason for the yellowing of rice seedling leaves? How to govern effectively? How to prevent and cure?

I. the causes of yellowing and dry tip of rice seedling leaves.

During the growth period of rice seedlings, the leaves are relatively young, stress resistance and disease resistance are relatively poor, coupled with the changeable weather, there will be some problems such as yellow leaves and dry tips of rice seedlings at the time of improper management.

1. Caused by the effect of de-fertilization

In particular, it is easy to occur when the seedbed is not cultivated or prepared with nutritious soil. Generally, it will occur obviously after the seedling 2.5 ~ 3 leaf stage, and there are generally symptoms such as yellowing of the seedling and dry leaf tip.

two。 Caused by improper management

Field temperature is too high or too low, humidity is too high or lack of water will also lead to malnutrition, resulting in yellow leaves, dry tip, or white, brown, the disease will spread downward. Improper venting of the leaves will also cause dry tip and temperature discomfort, which is more obvious at the general tuyere.

3. Caused by diseases and insect pests

There are great differences in temperature changes, improper management will lead to the occurrence of bacterial wilt and bacterial wilt, especially it will lead to seedling yellowing, dry tip withering and multi-spot wilt. The damage caused by mosses and horses will cause the leaves to dry up, which looks like burning from a distance. If you peel off the rolled leaves, you can see the insects.

4. Caused by fertilization or improper application of pesticides

Foliar supplementary fertilizer, pest control, if the concentration is too high, or uneven spraying, or did not wash seedlings in time after spraying, it is easy to cause leaf burns. There are chlorosis, yellowing, or leaf tip drying and other phenomena.

Second, how to govern effectively

1. For the fattening phenomenon

Attention should be paid to the timely selection of high-nitrogen water-soluble fertilizer or urea + potassium dihydrogen phosphate foliar supplement and mitigation.

two。 For improper management

Should pay attention to timely release the film to refine the seedlings, the seedling bed should not be too short of water, should not be watered too much. In addition to strengthening daily management, it can be alleviated by spraying Biyou in time after occurrence, or brassin + alginic acid, or American star + potassium dihydrogen phosphate. Enhance stress resistance, disease resistance, promote rapid recovery.

3. For diseases and insect pests

Blight should be promptly sprayed with Jiashuangfu, or Ruimiaoqing and other agents + rooting agent, or American star, or alginic acid control. Moss horses can be sprayed with thiamethamide, or imidacloprid, or carbosulfan and other control.

4. Caused by fertilization or improper application of pesticides

In addition to timely strengthening water and fertilizer management, it is necessary to timely foliar spray green protection, or brassin + alginic acid or American star relief, in order to alleviate drug damage and quickly restore normal growth.

Third, how to prevent and cure

1. Spraying organophosphorus pesticides such as trichlorfon, probophos, chlorpyrifos, triazophos, phoxim and other organophosphorus pesticides in rice fields may cause damage to rice when the dosage and concentration are too high, and small brown spots appear on the leaves, especially in the high temperature period.

two。 The yellowing of rice leaf tip may be caused by potassium deficiency, and spraying nitrogen fertilizer such as urea will aggravate the symptoms of potassium deficiency. If there is no yellowing in the healthy part of rice leaves caused by nitrogen deficiency, do not spray urea. If there is yellowing in the healthy parts of rice leaves, you can spray urea and potassium dihydrogen phosphate mixed with 500 grams of urea and 100 grams of potassium dihydrogen phosphate for every 50 kg of water.

3. The concentration of potassium dihydrogen phosphate sprayed in rice fields should not be too high, otherwise it may cause damage to rice seedlings, and it is generally sprayed at the concentration of 0.2% Murray 0.3%.

4. For rice varieties with reddish and yellowing leaf tips, fertilizer and water management should be strengthened to avoid long-term stagnant water and retting roots in the field.