Some gardeners prefer dusters to sprayers because they eliminate the need for mixing chemicals. All you do is pour the dry pesticide or fungicide into the container and start pumping. There is also less waste, since you can return the unused powder to its original container instead of throwing it away. However, because the dust can travel only a relatively short distance and is easily blown off course by the slightest breeze, dusters are useful primarily in small gardens or greenhouses.
Good dusters work on each stroke of the pump to maintain a constant fine cloud of material. Choose one with a nozzle that adjusts up or down; this will make it easier to coat the underside of leaves.
Hand pumps are all essentially the same. The difference is largely in how much pesticide they will hold. The smaller ones, which hold only about 4 ounces, are good for spot applications in small areas.
Larger hand pumps hold about 1 pound of dusting material. Extension wands of up to 20 inches will give you precise application control and keep the pesticide away from you. For really big jobs, use the crank duster. This is made of epoxy-coated galvanized steel and will hold about 8 pounds of average-weight dust. It can be used for crop dusting or for mosquito control. The cranking action does three things at once: it keeps the dust agitated in the hopper, it premixes the dust with air in the mixing tube, and it turns a high-speed fan to deliver the dust. Attachments for the crank duster include either a straight tube that makes it possible to work close to the ground without stooping excessively or a flexible Y-tube for covering two rows at a time.
Keep dusters clean. Tap them to remove all the material that remains in the cracks and clings to surfaces. Lubricate with graphite, not oil—the powdered materials will stick to oil.