Pesticide efficacy trial on pecan aphid control

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