The Fog

The major consideration with pesticidal fogging regards droplet size and the time the droplet stays aloft.  Fogging operations have historically been conducted in confined spaces due to the drift potential of small droplets.  With regard to outside applications, this phenomenon becomes even more important.  Florida experiences some weather patterns that result in completely calm or “still” air, which is a requirement for fogging outdoors.  Fog droplets range from 1 to 10 microns in size.  Those at the high end of the range take about 15 minutes to fall 10 feet in still air, while those at the low end may take over a day to drop the same distance.  As a result, drift depends more on the irregular movement of turbulent air than on gravity.   

With citrus psyllid and leafminer on the minds of most citrus pest managers, there becomes a impetus to consider using pest management tools in varying manners to increase the efficacy or speed of pest management or decrease overall costs.  One of the considerations given by managers is the use of fogging to penetrate canopies and reach insects in secluded feeding sites.  However, there are a number of drawbacks to fogging, the main one being that there are no pesticides labeled for citrus that allow this application type. 

When a pesticide is registered, the registration allows the product to be applied to certain sites by certain methods.  A current search of EPA’s pesticide registration database does not reveal any citrus pesticides that are registered for fog application.  Furthermore, the labels specify a certain amount of diluent that must be used to apply the product, and it is contingent on the pest manager to comply with specifications regarding application whether by ground or air.  (Crops & Soils, Spring 2008).