Articles
Using a double-sided volute sprayer to control scab in tall pecan trees
Article number
1420_33
Pages
243 – 250
Language
English
Abstract
Pecan (Carya illinoinensis) is an important specialty crop in the southern United States.
Scab (caused by Venturia effusa) is the major biotic constraint to pecan production in the southeastern region.
Control of scab relies on large orchard air-blast sprayers.
Some have been adapted to include a volute on one side to project spray higher into the canopy due to a decline in coverage with height.
A grower-designed and engineered double-voluted sprayer (DVS) was assessed for spray coverage and scab control compared to a standard, non-voluted sprayer (SS). Spray coverage studies showed that spray using the DVS sprayer resulted in significantly greater spray coverage at heights measured >13 m (up to 19 m), with DVS coverage ranging from 18.4 to 14.1%, compared to coverage using the SS, which ranged from 7.9 to 2.9%. The slope in decline of spray coverage with height was significantly shallower with the DVS sprayer, and spray profiles reflected these differences.
Over three seasons, scab control was either equal too, or superior using the DVS sprayer.
In 2017, mean scab severity for the control was 9.07, for the DVS was 0.19, and for the SS was 0.24%, respectively; in 2018 severity was 84.3, 18.4 and 29.1%, respectively; and in 2019 was 32.7, 7.0 and 11.6%, respectively.
There were no discernable gradients in scab severity with either sprayer in 2017, but in 2018 the difference was significant, with the DVS having a shallower gradient, and in 2019 the slope was numerically less steep with the DVS compared to the SS. Thus, the DVS provided greater spray coverage at heights >13 m when compared to the SS sprayer, and disease control was numerically or statistically greater overall when using the DVS. DVS sprayers may offer economical, superior scab control in pecan orchards with trees >13 m tall.
Scab (caused by Venturia effusa) is the major biotic constraint to pecan production in the southeastern region.
Control of scab relies on large orchard air-blast sprayers.
Some have been adapted to include a volute on one side to project spray higher into the canopy due to a decline in coverage with height.
A grower-designed and engineered double-voluted sprayer (DVS) was assessed for spray coverage and scab control compared to a standard, non-voluted sprayer (SS). Spray coverage studies showed that spray using the DVS sprayer resulted in significantly greater spray coverage at heights measured >13 m (up to 19 m), with DVS coverage ranging from 18.4 to 14.1%, compared to coverage using the SS, which ranged from 7.9 to 2.9%. The slope in decline of spray coverage with height was significantly shallower with the DVS sprayer, and spray profiles reflected these differences.
Over three seasons, scab control was either equal too, or superior using the DVS sprayer.
In 2017, mean scab severity for the control was 9.07, for the DVS was 0.19, and for the SS was 0.24%, respectively; in 2018 severity was 84.3, 18.4 and 29.1%, respectively; and in 2019 was 32.7, 7.0 and 11.6%, respectively.
There were no discernable gradients in scab severity with either sprayer in 2017, but in 2018 the difference was significant, with the DVS having a shallower gradient, and in 2019 the slope was numerically less steep with the DVS compared to the SS. Thus, the DVS provided greater spray coverage at heights >13 m when compared to the SS sprayer, and disease control was numerically or statistically greater overall when using the DVS. DVS sprayers may offer economical, superior scab control in pecan orchards with trees >13 m tall.
Publication
Authors
C.H. Bock, M.W. Hotchkiss, B. Paulk
Keywords
spray deposition, fungicides, pecan insect pests, disease management
Groups involved
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