Does low-volume spraying really work? The principle behind it

The question heard most often from farmers who have just seen a spraying drone is "Is that little water really enough?"

It is a good and reasonable question, because for people who have sprayed with a backpack sprayer all their lives, water running until the leaves are soaked is the sign that "it's covered".

Water is not the pesticide

What kills insects or controls weeds is the active ingredient, not the water. Water is only the carrier. If the amount of active ingredient per rai stays the same, using less water does not mean applying less product.

What changes is the concentration

Less water with the same amount of product means a more concentrated solution, so each droplet carries more of the product. The point to watch is that some products have a concentration limit that is safe for the crop. Raising the concentration beyond what the label specifies may burn the leaves. This is why you must read the label and ask someone knowledgeable, not work it out yourself from proportions.

Why little water still gives full coverage

Because the propeller downwash carries the droplets into the canopy, instead of relying on a volume of water to run over the whole plant. Coverage comes from how the droplets are spread and the force of the air, not from the volume of water.

The benefits that follow

Far less water to carry into the field, which is a heavy burden in fields far from a water source; longer continuous work before refilling; and less water running wastefully into the ground.

Limits that must be accepted

Some jobs really do need a lot of water, such as spraying that must run down to the base of the plant or the soil surface. In cases like these a drone may not be the most suitable tool, and claiming that drones can do every job is overselling.

How to check coverage is really complete

Place water-sensitive paper at various points in the field, both on top of the canopy and under the leaves, then look at the droplet marks after the drone flies over. This gives you an answer you can see with your own eyes instead of guessing, and it is the method used in research.
Important note
This article explains general principles. It is not a recommendation for any specific chemical. Suitable mixing rates and timing differ by substance, crop, growth stage and field conditions. Always treat the product label as the authority, and ask our staff or an agricultural specialist before deciding.