Hot temperatures and high humidity swept through much of the state last week. Undoubtedly, many of you were busy applying plant protectants at your facility. A great deal of thought is usually given to product selection, application rate and timing, spray volume, etc., but how much thought is given to the type of nozzles on your sprayer?
Spray nozzles affect the amount of product applied to an area, uniformity, and the potential for drift. Most nozzles operate between 30 and 60 psi and as pressure increases droplet size decreases and the potential for drift is greater. The four nozzle types most commonly used for turf applications are: flat-fan, air-induction, pre-orifice flat-fan, and flood-type nozzles.
Flat-fan (A): These are the most common nozzles used for turf applications and produce a fine to medium droplet. Spray coverage is excellent but drift may be a concern.
Air-induction (B): These nozzles produce a medium to coarse droplet which shatters upon contact with the leaf blade to provide better coverage. The potential for drift is reduced with air-induction nozzles.
Pre-orifice flat-fan (C): These nozzles reduce pressure internally and produce a larger droplet than the traditional flat-fan nozzles. As a result, the potential for drift is greatly reduced.
Flood-type nozzles (D & E): These nozzles produce extremely coarse droplets and drift is greatly reduced. These nozzles are great for applying products that must reach the soil but are not recommended if good coverage of the leaf blade is required.
Critical factors to consider when selecting nozzles are droplet size, chemical mode of action, and the location of the targeted pathogen. Contact mode of action products require thorough coverage of the leaf blade in order to be effective. These types of products should be applied through a nozzle which produces a fine to medium droplet size. In contrast, products that target a pest in the soil can be applied through nozzles which produce much coarser droplets.
The goal when selecting nozzles should be to achieve good coverage while minimizing drift. Products generally fail to provide adequate control when spray volumes are too low and droplet size is too coarse to provide adequate coverage. Research has shown that air-induction nozzles provide equivalent control compared to flat-fan nozzles while reducing the potential for drift.
More detailed information about nozzle selection may be viewed at: http://www.turf.uconn.edu/pdf/research/kaminski/gcm_74_83.pdf
Graduate Research Assistant