Entomology
Extension and Research Program at The West Virginia University
Experiment Farm in Kearneysville
Evaluation of a Tunnel Sprayer for Dwarf Apples
Pesticides are typically applied to fruit trees with
airblast sprayers to provide protection from insects and
diseases. This method of spray application is inefficient and
contributes to environmental contamination because of drift to
non-target areas. With the increasing urbanization of many rural
agricultural areas, there is greater public concern regarding
spray drift and a need to improve spray application. The
increased planting of dwarf apple trees has provided an
opportunity to address some of these concerns with over-the-row
tunnel spray systems. The objective of this study was to evaluate
spray deposit and pest control with a tunnel sprayer constructed
by BEI, Inc. in South Haven, MI in comparison with a conventional
airblast sprayer. The tunnel sprayer was equipped with either two
opposing pairs of CurtecŪ cross-flow fans or two sets of three
opposing ProptecŪ fans. Spray was delivered with 4 hollow cone
nozzles on each CurtecŪ fan and a single rotary controlled
droplet atomizer on each ProptecŪ fan. Various operating
parameters evaluated included fan orientation, spray volume and
sprayer travel speed. This study was conducted in a 3-wire
trellis apple orchard at the WVU Experiment Farm consisting of
‘Delicious', ‘Golden Delicious' and ‘York'
cultivars, planted at 6 x 12 ft and measuring 9 ft in height and
6.5 to 9 ft in width. Two water-soluble food dyes were used to
assess spray deposit on the top and bottom surface of leaves in
the periphery and center regions of target trees and spray drift
to an adjacent row. A series of four tests were conducted from
June through August, with information gained from one test used
to help determine operating parameters for the next test. The
CurtecŪ cross-flow fans resulted in the most uniform spray
deposition on the target trees and the least spray drift on the
adjacent tree row. Spray deposition on target trees with the
ProptecŪ fans was comparable to the CurtecŪ fans early in the
season, but became less uniform as the season progressed, and
drift was also greater. Spray deposition and uniformity of
coverage at 5 mph travel speed was as good as or better than at 3
mph with both the CurtecŪ and ProptecŪ fans. Fan outlet
orientation (one side angled 7.5 forward and the opposite side
angled 7.5 backward, or both sides angled 15 backward) did not
significantly affect spray deposition, uniformity of coverage or
drift with either fan type, however, there appeared to be less
spray deposit on the inside walls of the tunnel when both sides
were angled backward 15 . There were no significant differences
in spray deposition on target trees and drift, and very little
difference in uniformity of coverage, with a spray volume of 20
and 75 gal/acre applied with the CurtecŪ fan. The tunnel
sprayer, with either CurtecŪ or ProptecŪ fans, provided greater
spray deposition on target trees, more uniform coverage, and less
drift than a commercial airblast sprayer. The tunnel sprayer was
evaluated for pest and disease control in comparison with a
conventional airblast sprayer in a full-season (12 application)
pesticide spray program. Data were collected on foliage pests
(spirea aphid, European red mite, and spotted tentiform
leafminer) and fruit pests and diseases (plum curculio, tufted
apple bud moth, fly speck, and rots) from the same planting and
cultivars used in the spray deposit study above. CurtecŪ and
ProptecŪ fans provided control that was equal or superior to the
airblast sprayer in 90 percent of insect and disease comparisons.
The CurtecŪ and ProptecŪ fans were comparable in performance in
85 percent of these comparisons. Performance of the CurtecŪ fans
at a spray volume of 20 gal/acre was equal or superior to that at
75 gal/acre in 90 percent of comparisons.
H. W.
Hogmire and D. L. Peterson (September 1996)
