Spraying cotton with fertilizer boosts yield and reduces pests and diseases

Spraying nitrogen fertilizer: Urea has the effect of destroying insect chitin. When cotton aphids (especially summer aphids) occur, mix urea, laundry detergent and water in a ratio of 4:1:400 to prepare a "wash-urea mixture" and spray it, which has a clear killing effect.

Spraying phosphorus fertilizer: During the adult occurrence period of cotton bollworm, using 1%-2% superphosphate leachate as a foliar spray fertilizer can convert oxalic acid into calcium oxalate and cause it to lose its attraction to cotton bollworm. The residual effect of each phosphorus spray is generally 2-3 days.

Spraying potassium fertilizer: Use 10 kg of plant ash, add 50 kg of water, soak for 24 hours and then filter, take the filtrate and spray it, which can effectively kill aphids on cotton. In the middle and late stages of cotton growth, foliar spraying with 1%-2% potassium chloride (or potassium sulfate, potassium nitrate) solution can prevent or reduce the occurrence of cotton red leaf stem blight.

Spraying boron fertilizer: Boron fertilizer is one of the nutrient elements essential for cotton growth and development. At the cotton bud stage, early flowering stage and boll stage, spray the leaves with 0.2% borax (or 0.1% boric acid) solution; at the bud stage spray 15-20 kg per mu, at the early flowering stage spray 35-40 kg, and at the boll stage spray 50-60 kg.

Spraying copper fertilizer: Use 1 part copper sulfate, 1 part lime and 200 parts water to prepare an equal-amount Bordeaux mixture. Spraying it at the cotton seedling stage can control cotton seedling diseases; spraying it at the boll stage can control boll diseases and reduce rotten bolls.

Spraying chlormequat: At the cotton bud stage, for cotton fields suffering from Verticillium wilt, spray 50-75 kg of 50 ppm chlormequat solution per mu, which can alleviate the condition.