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Soybean Rust Disease Management Page
Q&A: Nozzle Package for Asian Soybean Rust
By Bobby
Grisso, P.E., Extension Specialists
Biological
Systems Engineering, Virginia Tech
Q. Could you tell me what style of tip, recommended pressure, tip spacing and any other information you may have so that I can get my sprayer ready now to apply fungicides?
A. Nozzles with a flat-fan pattern, compared to cone pattern, seem to be better choices for soybean rust. However, we are not recommending use of air-induction nozzles to treat rust, even though they provide flat-fan patterns. These nozzles produce relatively courser droplets, which do not provide the desired coverage for fungicides in soybeans.
Set up your sprayer so that the nozzle spacing is 20 inches, and then adjust the boom height (above the target) so that proper overlap is achieved on top of the canopy. Check the nozzle catalog for the proper boom height depending on the spray pattern angle of the nozzle.
A small size (size 02 or 03) Turbo TeeJet Duo at 60-70 psi is a better choice than the same size TwinJet. Do not use size 02 and 03 TwinJet nozzles operated at higher pressures, because they create too many small droplets that do not penetrate into the canopy. If you use TwinJet nozzles, the minimum size you should select is size 04 (TJ 8004).
Overall recommendations:
· Choose the appropriate size and type of nozzles and operate them at a pressure that will allow them to produce “Medium-size” droplets. (Nozzle catalogs have info on which nozzles at what pressures produce droplets that are categorized as "Medium.")
· Calibrate the sprayer.
· Keep spray volume (application rate) at or above 20 gallons per acre.
· Try running the sprayer at slightly higher pressures (60-70 psi) than usual. Higher spray pressures usually help the droplets penetrate into the canopy better.
· If spray drift is a concern, you may use some of the low-drift nozzles (other than air induction nozzles). These nozzles allow you to increase the pressure without increasing the number of small, drift-prone droplets.
· To improve coverage, if applicable, use directed spraying.
· Use twin nozzle/pattern technology. Two nozzles (or spray patterns) angled (one forward one backward) work better than single nozzles spraying down.
· Air-assisted spraying usually provides the best coverage and droplet penetration into canopy when beans reach their full or near-full growth stage.
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