When we think about space spraying mosquitoes, midges, flies or stored product pests, what we are doing is producing a droplet cloud with specialised equipment that maximises its chances of hitting the target, whether in the air (on the wing) or on surfaces. The products used for this purpose are designed for rapid knockdown rather than residual control. This offers rates of active ingredient that are just enough to kill the targeted insects, leaving behind little or no residues a short time after application. By doing this, there a fewer restrictions on where they can be applied and handled.
By treading this thin line between rate and knockdown control, it is critical that the droplet cloud stays viable as intended and does not deteriorate before it has a chance to hit its targets.
The two main pathways that this degradation can occur is via the equipment being used and evaporation of the droplets in the air. In both cases, a good understanding of the formulation technology chosen will dictate equipment selection and calibration, and if any carriers are required to be added to improve and protect the formulation.
With formulations reliant on petroleum solvents (either built into a ready-to-use formulation or as a tank mix) the addition of petroleum solvent is often necessary when thermal/hot fogging to protect the active ingredient from tank to target. Without these additives, rapid active ingredient breakdown will occur in a thermal fogger (hot fogger) by the heat generated by the equipment and the droplet life in the air will be shortened due to evaporation.
True water-based formulations such as Aqua K-Othrine® are diluted with water and there is no need to add solvents to protect the droplets, saving money as well as the associated emissions given off by these compounds at application. It is important to note that there are some water-based ‘formulations’ available that then are diluted with solvents for use, which are not true water-based technology. A true water-based formulation like Aqua K-Othrine does not require petroleum solvents to be added when cold fogging or, importantly, when hot fogging.
With true water-based formulations, an understanding of the correct equipment selection and calibration is critical to their performance. For instance, thermal foggers can require their standard fog tube replaced with one designed for true water-based fogging, which injects the solution further down the fog tube than with solvent-based products. At this point, the temperatures are lower and less likely to degrade the solution and can be combined with dedicated nozzles that optimise fluid flow. Equipment upgrade kits can keep the standard fog tube and add an additional injection point later in the fog tube. Some equipment is already claimed to have these features built-in and have a selection lever for solvent and water-based products.
What is important is that just by injecting the solution further along the fog tube does not guarantee that the true water-based formulations will not be affected in some way. The best thermal fogging equipment manufacturers can provide technical data proving that its design protects water-based formulations, so be sure to ask.
A criticism of water-based technology when using hot/thermal foggers is that it is less visible than solvent based technology. On their own, true water-based space sprays are indeed less visible through a thermal fogger. Expect them to not be a fluffy white cloud like that seen with solvent-based products, but they are still nevertheless visible. If it is important to you to increase the visibility of the droplet cloud, the addition of a carrier product based on ethylene glycol will achieve this – but it is not necessary.
With ULV space spraying (cold fogging), the situation is much simpler. ULV space spraying is ideally suited to water-based technology – it is simply a matter of adding a product like Aqua K-Othrine to the right amount of water determined by your calibration and you’re on your way.
Because of the formulation technology in Aqua K-Othrine, droplets are not readily evaporated and remain viable to deliver peak performance. Without such formulation technology a standard water-based formulation like a suspension concentrate will rapidly evaporate before it has any chance of reaching the target.
To better understand how to make the switch, modify or purchase the right equipment and to get the most out of water-based space spraying, talk to the team at Envu and your preferred pest control distributor.
For further information:
(m) 0418 390 803
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