Spraying: It is important that the plant be thoroughly covered. If the label instructions say wet thoroughly or to the drip point, apply as much spray as possible, until the plant begins to drip. To get thorough coverage, spray the plant from 2 or 3 directions, and from underneath as well as from above. If there is a breeze, spray downwind to avoid having the mist drift back to you.
Dusting: Since dust is carried by air currents, it is especially important that dusting be done when the air is still. Apply a thin coat of dust, not a heavy layer. Work the duster vigorously, so that the air currents carry the dust onto the foliage and cover all the surfaces of the leaves. Dust from the bottom of the plant as well as from the top.
Spreader-stickers: These additives perform 2 functions: they break the surface tension of the spray droplets, preventing them from beading on waxy leaves and helping them to penetrate wax-covered insects, such as mealybugs and scales. They also make pesticides adhere better in rainy weather.