What precautions should be taken when mixing foliar fertilizers with pesticides?
1. Choose foliar fertilizers suited to the vegetable variety. For vegetables harvested mainly for their leaf heads, leaf rosettes, or young tender stems and leaves, choose foliar fertilizers rich in nitrogen; for vegetables harvested mainly for their fleshy roots and tubers, such as radishes and potatoes, choose foliar fertilizers rich in potassium. For those harvested for their fruits, pods, or beans...
Spraying foliar fertilizer is one of the common methods of foliar topdressing used by vegetable growers. In practice, to save trouble, vegetable growers mostly mix foliar fertilizer with pesticides and spray them together. In fact, because various fertilizers and pesticides have different properties, improper mixing can affect the effectiveness of the fertilizer and pesticide, or even cause fertilizer burn or pesticide damage. It is recommended that vegetable growers pay attention to the following aspects when mixing foliar fertilizers with pesticides.First, make sure the foliar fertilizer and pesticide remain stable in character after mixing. Some foliar fertilizers may undergo chemical or physical reactions when mixed with pesticides, affecting the effectiveness of the fertilizer and pesticide or even causing fertilizer burn or pesticide damage. For example, foliar fertilizers containing boric acid, ferrous sulfate, and similar ingredients are mostly acidic, while copper preparations such as copper hydroxide are alkaline. If mixed, they readily react and affect each other's effectiveness. Therefore, when mixing foliar fertilizers with pesticides, first pay attention to acidity and alkalinity. Also carry out a test to observe whether flocculation, precipitation, color change, or bubbles appear after mixing. If the liquid shows adverse signs, it is not suitable for mixed use. Even if the liquid has good physical properties after mixing, first conduct a small-scale test to see whether fertilizer burn or pesticide damage easily occurs, then use it on a large scale.
Second, pay attention to the order in which the foliar fertilizer and pesticide are added when mixing. When preparing the spray, vegetable growers should first mix one single agent with a sufficient amount of water, then use this liquid to dilute the other single agent. Do not first mix the two single agents and then dilute with water, to avoid adverse reactions. When mixing, the order in which the foliar fertilizer and pesticide are added to the water is usually: foliar fertilizer, wettable powder, suspension concentrate, aqueous solution, emulsifiable concentrate, added in sequence; stir thoroughly and evenly after each addition before adding the next.
Third, the liquid should be prepared and used immediately. Although some foliar fertilizers and pesticides show no adverse reaction when just mixed, standing for a long time tends to produce slow reactions, causing the fertilizer and pesticide to lose effectiveness or even causing fertilizer burn or pesticide damage.