Agricultural spray nozzles can be described as devices that facilitate spray pattern formation of a pesticide being applied. Nozzle manufacturers prescribe a range of liquid pressure that is sufficient to initiate pattern formation. This pressure range is critical in controlling problems such spray drift – an undesired occurrence which results in spraying pesticides on non-target surroundings and/or organisms such as water drainages and wildlife. The consequences of spray drift can result in reduced effectiveness of pest repulsion, prevention, elimination, or mitigation. In some cases, spray drift can result in pests developing pesticide resistance, thereby affecting the efficacy of future pesticide applications.
Potato farmers in Atlantic Canada commonly apply pesticides against weeds, insects, and fungi. However, simply applying the correct pesticide may not be sufficient to produce desired results. Farmers need to use the correct nozzle tip based on many factors. These include, but not limited to, what pest they are spraying against, sprayer operation speed, nozzle pressure, and height of application. Even though operators are trained and licenced to ensure that all these factors are optimised, spray drift may still occur. Problems associated with sprayer bounce caused by uneven agricultural land still prevail. A quick in-field solution lies in operators moving at low speeds, but this has the potential to increase equipment and labour expenditure per acre of land being sprayed.
Most nozzles are tested under laboratory conditions with water at a given temperature. Nozzle catalogues provided by manufacturers will have spray information for fixed laboratory environment conditions. However, when pesticides are mixed with water, the resulting liquid properties are altered depending on the chemical being sprayed. This liquid modification presents another challenge in combating spray drift. In my research, the effect of pesticide mixes on liquid properties will therefore be investigated.
New nozzle technologies have been introduced to minimise spray drift by about 80%. However, some of these nozzles show increased spray drift potential when used with some nozzle valve technologies. Therefore, careful pairing is of nozzles and nozzle valves is also an important part of my research. Nozzle and nozzle valve pairing is even more important because my research is focussing on spot applications – where any form of spray drift can result in missing the target altogether.
During use, the condition of nozzles should be checked and recalibrated often throughout the growing season. Nozzle wear can occur overtime with the rate of wear being affected by factors such as the nature of the pesticide, application pressure, frequency of use, and environmental conditions. It is also worth noting that nozzle wear can enhance spray drift as the nozzle tip is altered from its original design.
The optimisation of all these factors is the primary goal of my research. Even though it is easier said than done, there is still room for improvement in ensuring pesticides are applied within limits of acceptable spray drift. Simply selecting the correct spray nozzle should not be the end to solving the spray drift problem. Manufacturers do their part by developing nozzles that enhance precision application of pesticides. As a precision spraying researcher, it is my responsibility to develop systems that facilitate pesticide application only where the pests exist with minimal or no drift. Possible solutions currently being explored include, but not limited to, using nozzles with coarse droplets, lowering height of application, angling nozzles on the boom, and developing constant nozzle pressure systems. I am of the view that optimisation will help in reducing spray drift and enhance environmental protection by preventing pesticide spraying on non-target surroundings and/or organisms.
