1. Deficiency

On the one hand, the yellow edges of the leaves are caused by the lack of nutrients, such as potassium deficiency: the middle and lower leaves are yellow ring leaves; the calcium deficiency, the top leaves are inlaid with gold edges.

Solution: timely supplement of potassium fertilizer (potassium dihydrogen phosphate or more potassium), foliar spraying of chelated calcium fertilizer, etc., if necessary, it can be combined with water flushing and foliar spraying.

2. Root injury

Root retting is caused by agricultural operations, such as injury to the root system itself or watering, which will reduce the ability of the root system to absorb nutrients and cause yellow edges on the leaves.

Solution: It is necessary to promptly apply fertilizers to maintain roots and promote root growth, such as Fangrun roots, more roots, dense roots, etc., to promote roots to grow new roots as soon as possible.

3. Salt damage

The concentration of the soil solution is too high and the salinization is serious, and the roots absorb a large amount of high-concentration soil solution, which will burn the edges of the leaves and turn yellow.

Solution: Water repeatedly to dilute the concentration of the soil solution. In the subsequent fertilization process, reduce the amount of chemical fertilizers, switch to fully water-soluble fertilizers, and increase the application of biological fertilizers or humic acid fertilizers.

4. Drug damage, gas damage

In this case, the middle and lower leaves are mostly damaged, the leaf margins turn yellow at the beginning, and the leaf margins scorch in the later stage. In the shed where the disease occurred, the number of sprays was more, which resulted in the yellow edge of the watermelon damaged leaves. In addition, when some smokers are used in the shed, if they are used for a long time or in a large amount, they will often turn the edges of the leaves into yellow.

Solution: Reduce the number of sprays or reduce the concentration of sprays. Combined with foliar sprays of nucleotides, brassinolide, Aidosine and cytokinin to alleviate the damage and promote the leaves to resume normal growth as soon as possible.