Benefits and Taboos of Adding Laundry Detergent to Pesticides, and Laundry Detergent-Based Pesticide Formulas

When selling pesticides, people often ask whether laundry detergent should be added. Adding laundry detergent when spraying can kill weeds! Is it true, and what are the benefits of adding laundry detergent when spraying pesticides? As far as the chemical composition of laundry detergent is concerned, it cannot kill weeds, or its effect is negligible.

But why do some technicians still recommend adding laundry detergent?

There is a key point here: laundry detergent can increase the viscosity of the pesticide solution, so that the solution can better adhere to the surface of plant leaves instead of dripping off, thereby improving the pesticide effect.

The role laundry detergent plays in this process is to increase the adhesion of the pesticide solution on the leaves, because the sodium alkylbenzenesulfonate contained in laundry detergent is a very good adhesive. After being mixed with pesticides, it can make the pesticide solution evenly adhere to the leaves, prevent the pesticide solution from forming a large number of water droplets on crop leaves and rolling onto the ground, increase the adhesion of the pesticide, and allow the pesticide to remain on crops for a longer period, making it more resistant to rain washing.

Adding laundry detergent to most pesticides does not affect pesticide efficacy, and it can be mixed with pyrethroid pesticides, phoxim, malathion, trichlorfon, dimethoate and most other organophosphorus pesticides, as well as the fungicide chlorothalonil.

What are the benefits of adding laundry detergent when spraying pesticides

When spraying pesticides to control diseases and insect pests, the pesticide solution easily forms a large number of water droplets on the leaves and then rolls onto the ground, directly affecting the control effect. Practice shows that adding neutral laundry detergent as an adhesive at 0.1% to 0.2% of the pesticide weight to the diluted pesticide solution can both reduce the loss of the pesticide solution and improve the control effect. Using 2500 times diluted fenpropathrin pesticide alone to control aphids, whiteflies, cotton bollworms, cabbage caterpillars and other pests on grain, cotton, vegetables and other crops gives a insecticidal effect of about 85%; after adding 0.2% laundry detergent, the insecticidal effect can reach more than 95%. Using this method in greenhouses gives a better control effect than in open fields, because the humidity in greenhouses is greater than in open fields, so the effect is better than outdoors.

The sodium alkylbenzenesulfonate contained in laundry detergent is an excellent adhesive. After being added to the pesticide solution, it can make the solution evenly adhere to the leaves, thereby greatly reducing the loss of pesticides; at the same time, it can also form an airtight film on the body surface of piercing-sucking pests such as aphids and whiteflies, causing such pests to suffocate and die.

The method of adding laundry detergent: first take neutral laundry detergent at 0.1% to 0.2% of the pesticide weight used and dissolve it in warm water, making sure it is fully dissolved for later use. When preparing the pesticide solution in the sprayer, first pour in the required pesticide solution, then add clean water up to one third of the sprayer capacity, then pour in the prepared laundry detergent solution, and finally add enough clean water so that the pesticide and clean water are fully and evenly mixed before use.

Adding neutral laundry detergent to most pesticides does not affect pesticide efficacy, and it can be mixed with pyrethroid pesticides, phoxim, malathion, trichlorfon, dimethoate and most other organophosphorus pesticides, as well as the fungicide chlorothalonil. However, it cannot be mixed with pesticides such as amobam, lime sulfur mixture, thiram, tricyclazole, thiophanate, carbendazim, dibrom, dichlorvos and others; if mixed with such pesticides, the efficacy will be reduced. To ensure the effect after mixing pesticides with laundry detergent, the mixing ratio of pesticide and laundry detergent must be strictly controlled, and the mixture should be used immediately after preparation to prevent phytotoxicity and reduced control effects.

Common pests controlled by adding laundry detergent and usage standards

Controlling pests (mites) (1). Use 400-500 times laundry detergent solution, spraying 50-60 kg of solution per mu each time, to control vegetable mites. (2). Use 600-800 times laundry detergent solution to control greenhouse whiteflies. (3). When insect pests occur on the surface of mushroom beds in edible fungus cultivation, spray 1%-2% laundry detergent solution, which has a very strong contact-killing effect on mushroom flies, adult mites, and old and young mites. (4). Prepare a mixed solution according to the ratio of 2% laundry detergent, 8% urea, and 90% water, which has a control effect on aphids, cabbage caterpillars, red spiders and other pests, and can also serve as foliar topdressing.

Improving the adhesion of pesticide solutions: add 0.05%-0.1% to pesticide solutions such as bisultap, Bacillus thuringiensis, and Serratia marcescens; add 0.1% laundry detergent to pesticide solutions such as carbendazim, iprodione, vinclozolin, and validamycin; add 0.1%-0.2% laundry detergent to pesticide solutions such as benomyl, mancozeb, and thiophanate-methyl plus sulfur; add 0.2% laundry detergent to pesticide solutions such as thiophanate-methyl, chlorothalonil, sulfur plus carbendazim, and copper oxychloride. This can reduce the surface tension of the pesticide solution, make the solution atomize more finely, and enhance adhesion, thereby improving efficacy. Generally, the effect can be increased by more than 20%-30%.

Which pesticides cannot have laundry detergent added?

Laundry detergent cannot be added during the use of all pesticides, because some pesticides themselves have very strong permeability, and adding a penetrant can easily cause excessive absorption by plants, leading to phytotoxicity.

For example: it cannot be mixed with pesticides such as amobam, lime sulfur mixture, thiram, tricyclazole, thiophanate, carbendazim, dibrom, dichlorvos and others; if mixed with such pesticides, the efficacy will be reduced.

Precautions for adding laundry detergent

1. It cannot be mixed with pesticides that decompose when exposed to alkali.

2. Mixed pesticide solutions should be used immediately after preparation.

3. Use with caution on beans and cucurbit vegetables to avoid phytotoxicity. Generally, a test should be carried out first, and it should be used only when there is no phytotoxicity.

4. When using formulations with added laundry detergent, the interval period should be appropriately shortened compared with ordinary pesticides, and re-spraying should be done promptly after rain.