Articles
Characteristics of spray coverage from large pecan orchard air-blast sprayers
Article number
1420_18
Pages
137 – 144
Language
English
Abstract
Pecan (Carya iliinoinensis) is a particularly tall orchard crop.
Achieving adequate coverage with sprays throughout the canopy profile is challenging.
Air-blast sprayers are typically used to apply sprays from the ground.
We performed a series of tests to ascertain the effects of spray volume, speed and use of a volute on characteristics of spray coverage in the absence of a tree canopy.
Kromekote spray cards were positioned on a vertical pole at heights of 5.0, 7.2, 9.4, 11.6, 13.8, 15.0, 17.2, and 19.0 m.
Spray with Vision Pink dye for visualization was applied without a volute at 2.4 or 3.2 km h‑1 and 470, 940, and 1870 L ha‑1, and with a volute at 2.4 or 3.2 km h‑1 and 470 and 940 L ha‑1. Spray coverage on cards was measured using image analysis.
For those sprays applied without a volute there was greater coverage at 5 m compared to 19 m.
But despite more coverage with higher volume, the effect was not constant with height as the difference in coverage between volumes applied declined with height, and at 19 m the differences among treatments were negligible.
The effect of speed was relatively small compared to volume, and also not consistent at different heights.
However, the volute-based treatments had greater coverage at 19 m compared to 5 m, although the effect was minimal with 470 L ha‑1. At 940 L ha‑1 spray coverage was greater, particularly at heights greater than 13.8 m.
Use of a volute at spray volumes less than 940 L ha‑1 may be marginal.
The results confirm previous studies on the effect of volume and speed on spray coverage in pecan tree canopies and further illustrate the limitations of orchard air-blast sprayers for spraying tall pecan trees.
Achieving adequate coverage with sprays throughout the canopy profile is challenging.
Air-blast sprayers are typically used to apply sprays from the ground.
We performed a series of tests to ascertain the effects of spray volume, speed and use of a volute on characteristics of spray coverage in the absence of a tree canopy.
Kromekote spray cards were positioned on a vertical pole at heights of 5.0, 7.2, 9.4, 11.6, 13.8, 15.0, 17.2, and 19.0 m.
Spray with Vision Pink dye for visualization was applied without a volute at 2.4 or 3.2 km h‑1 and 470, 940, and 1870 L ha‑1, and with a volute at 2.4 or 3.2 km h‑1 and 470 and 940 L ha‑1. Spray coverage on cards was measured using image analysis.
For those sprays applied without a volute there was greater coverage at 5 m compared to 19 m.
But despite more coverage with higher volume, the effect was not constant with height as the difference in coverage between volumes applied declined with height, and at 19 m the differences among treatments were negligible.
The effect of speed was relatively small compared to volume, and also not consistent at different heights.
However, the volute-based treatments had greater coverage at 19 m compared to 5 m, although the effect was minimal with 470 L ha‑1. At 940 L ha‑1 spray coverage was greater, particularly at heights greater than 13.8 m.
Use of a volute at spray volumes less than 940 L ha‑1 may be marginal.
The results confirm previous studies on the effect of volume and speed on spray coverage in pecan tree canopies and further illustrate the limitations of orchard air-blast sprayers for spraying tall pecan trees.
Publication
Authors
C.H. Bock, T.E. Cottrell, M.W. Hotchkiss
Keywords
pecan insect pests and disease, disease control, fungicides, pecan scab, Venturia effusa
Groups involved
Online Articles (45)