Reasons why product dose, spray mix rate and drop size can vary
Learn why a range of product doses and spray mix/water volume rates can be given on the label. Review our examples which show options for setting up your knapsack sprayer to deliver a chosen spray mix/water volume rate and drop size.
Definitions and label statements
The product dose rate is the amount of formulated pesticide to be evenly applied over the spray area. The pesticide label will often state this as a volume or weight of product for an area of land or crop e.g. 4 L/ha or 2 kg/ha. As the quantities of product are relatively small and the areas relatively large, the pesticide has to be mixed with water to form a spray mix. This gives a volume of liquid that can be safely and effectively applied by a sprayer. The pesticide label states this volume as a spray mix or water volume rate e.g. 200 – 400 L/ha.
Your pesticide label could advise a drop size to use. This may be for reasons of safety: larger drop sizes tend to drift less. Or it might be for reasons of efficacy: contact pesticides can need larger spray mix volumes applied in smaller drops to get the best spray cover.
Most pesticide products are used to control a wide range of pest species in a wide range of situations. For example HALLMARK ZEON® is registered in the United Kingdom to control over 20 different insects and can be used in over 20 different crops. This range of uses makes it necessary to state on the label a range of pesticide doses, spray mix/water volume rates and drop sizes. You need to choose those that are optimal for your intended use.
Factors that may cause product dose, spray mix/water volume rate and drop size to be varied
Product dose rate
Higher product dose rates may be needed to control larger/older pests: lower product dose rates might be used to control younger/smaller pests. Higher product dose rates may be needed to control one species of pest whereas another species may be controlled at a lower product dose rate.
Spray mix/water volume rates
For each spraying task you will need to decide which type and size of nozzle, at what pressure, will deliver the spray mix volume rate and drop size that you need to produce the right cover of spray drops safely.