PECAN:
In 2013, Drs. Mark
A. Muegge and Salvador Vitanza evaluated the efficacy of several
insecticides for black-margined aphid (BMA) control. This study was conducted in a commercial
pecan orchard near Fabens, TX. A single
pecan tree constituted an experimental unit.
Each experimental unit was bordered by untreated pecan trees as buffers
to help reduce potential drift contamination.
Experimental units were arranged in a randomized complete block design
with 10 treatments replicated 4 times.
Insecticide applications were made using a high pressure sprayer
calibrated to deliver 100 gallons per acre (gpa) at 100 pounds per square inch (psi). From each experimental unit 3 randomly
selected compound leaves were examined for BMA.
Adult and nymph aphids found were counted separately and recorded. Treatments were applied on 11 Oct after
pre-treatment samples had been collected.
Post treatment samples were taken at 10 and 25 days after treatment. All data were subjected to analysis of
variance (ANOVA). Treatment mean
separation was performed using Fisher's Protected LSD (P=0.05).
Although
total BMA densities were moderately high they never exceeded economically
damaging population densities throughout the duration of this test. Prior to treatment application, BMA adult and
nymph population densities were statistically equal among untreated check and
treated plots. At 10DAT the Induce,
Agriflex, Agrimek and Admire Pro treatments did not significantly reduce BMA
adult population density. All
treatments except Agriflex and Admire Pro significantly reduced BMA nymph
population densities. At 25DAT only the
Beleaf treated trees had significantly lower BMA adult population densities
relative to the untreated check trees and BMA nymph populations were not significantly
lower in any of the treated trees relative to the untreated check. However, population densities of BMA nymphs
were substantially lower in the Endigo, Voliam and Beleaf treated trees
relative to the untreated check trees.
Interestingly, the NIS and Agriflex treated trees had significantly
higher BMA nymph population densities relative to the untreated check
trees. Whether this result is a real
cause and effect or a result of experimental and or sampling error requires
further studies.
Mean BMA adults/3 Compound Leaves
|
Mean BMA nymphs/3 Compound Leaves
|
||||||
Treatment
|
Rate
(oz/acre)
|
0 DAT
|
10 DAT
|
25 DAT
|
0 DAT
|
10 DAT
|
25 DAT
|
UTC
|
-
|
8.2
|
7.8ab
|
4.2bc
|
14.3
|
24.2a
|
11.3bcd
|
Induce
|
4.8
|
6.9
|
7.9a
|
9.2a
|
10.7
|
11.8bc
|
31.7a
|
Agriflex+NIS
|
5.5
|
4.6
|
5.7abc
|
6.4ab
|
11.7
|
15.6ab
|
30.6a
|
Agrimek+NIS
|
2.5
|
8.7
|
5.5abc
|
5.7bc
|
20.8
|
13.4b
|
17.9bc
|
Admire
Pro
|
2
|
4.6
|
4.7bcd
|
4.8bc
|
7.6
|
14.7ab
|
15.0cb
|
Endigo
|
5
|
10.8
|
4.2cd
|
3.1cd
|
26.3
|
5.8bc
|
5.7cd
|
Water*
|
100g/a
|
10.1
|
3.9cd
|
4.8cb
|
17.8
|
10.7bc
|
19.7ab
|
Voliam
Express
|
9
|
10.2
|
3.2cd
|
3.4cd
|
21.6
|
6.3bc
|
9.7bcd
|
Fulfill+NIS
|
4
|
8.7
|
2.7cd
|
4.7cb
|
9.8
|
2.5c
|
12.3bcd
|
Beleaf
|
2.8
|
8.4
|
2.4d
|
1.0d
|
21.3
|
2.2c
|
1.9d
|
LSD (P=0.05)
|
6.0
|
3.2
|
2.9
|
15.8
|
10.6
|
12.5
|
|
P>F
|
NS
|
0.0039
|
<0.0001
|
NS
|
0.0017
|
<0.0001
|
|
