standardized evaluation of insecticide efficacy against sugarcane aphid

Standardized Evaluation of Insecticide Efficacy Against Sugarcane AphidS. Stewart, A. Catchot, D. Kerns, G. Lorenz, N. Seiter, D. Buntin, Alana Jacobson, M. Way. F. Reay-Jones, M. Jones, A. Zarrabi, Tom Royer, Kris Giles, J. P. Michaud, G. Nuessly, and R. Bowling

Design Replicated, small plot, RCB Application timing against threshold, rapidly increasing populations 5 Core treatments

◦ Check, Transform (1 oz), Sivanto (4 oz), Centric (2 oz or 2.5), Lorsban Advanced or Nufos (32 oz)

Only used data collected after a single application◦ Classified as 3-5, 7-10, 13-15 days after treatment

Optional treatments at researcher discretion◦ Tests were over-treated at discretion of the researcher for other pests (e.g., Besiege

or Prevathon) or to flare aphid infestation (e.g., pyrethroid)

Sampling of leaves (10 total)◦ Typically 5-10 lower/mid canopy and 5 flag leaves

Yield data were collected in several trials◦ But I’m only going to show one example

Analysis Used tests with the 5 core treatments for primary analysis

Response variable was average aphid numbers per treatment in each trial (blocked by trial)◦ 3-5, 7-10, and 13-15 DAT◦ Mid-canopy, flag leaf, and total (mid + flag)◦ PROC GLIMMIX using LS Means for separation (α = 0.05)◦ Square root transformation of data prior to analysis◦ Untransformed LS-means are presented

Comparisons of some “optional” treatments are included◦ Paired t-test of trial averages

Across All Rating DatesA bunch of data (21 tests, 61 test*date ratings)

NUMBER APHIDS PER LEAF PERCENT CONTROL

* Transform 1+ oz, Sivanto 4+ oz, Centric 2+ oz, Endigo 4 oz, Strafer 3+ oz

P = 0.0002

P < 0.0001

Numbers of Aphids in Check PlotsFor tests having 5 core treatments

Number of Trials

*

* Omitted from analyses

Numbers of SCA at 3-5 DAT

P < 0.0001N = 9 tests

Numbers of SCA at 7-10 DAT

P < 0.0001N = 12 tests

Numbers of SCA at 13-15 DAT

P < 0.0001N = 9 tests

Numbers of SCAAverage - Flag + Lower Leaf

A

BBBB

A

B

CCC

A

AB

BB

C

P < 0.0001 for all

9 Trials 12 Trials 9 Trials

Average Percent Control of Two Transform Rates within the Same Tests

12 TrialsP = 0.247

Paired, 1 tailed t-test of trial averages

a a

Average Percent Control of Two Sivanto Rates within the Same Tests

Paired, 1 tailed t-test of trial averages

a a

P = 0.065 P = 0.028

A B

(8 oz in one test)

Average Percent Control of Optional Treatments Compared with Check Plots in the Same Tests

(Number of trials)

* P < 0.05 (paired, 1 tailed t-test of trial averages)

* *** * *

SCA Trial (Case Study, Milan TN, 2015)Mid-Canopy Leaves

Days After Treatment

One application made during early flowering

SCA Trial (Case Study, Milan TN, 2015)Flag Leaves

Days After Treatment

One application made during early flowering

SCA at Trial Milan (2015)

SCA Trial at Milan, YieldSingle Application (2015)

All treatments sprayed with Besiege at 7 oz/acre during early bloom

Threshold was reached at about the time of head emergence

Conclusions Sivanto provided the best control of SCA Transform and Centric were similar and next best There was not a large rate response with Transform (1 vs. 1.5 oz) or Sivanto (4 vs. 7 oz)

Lorsban, Dimethoate, and Pyrethroids were so-so, bad, and worse, respectively

Some candidates showed promise, at least at high rates◦ E.g. Strafer and Carbine

An obvious insecticide strategy would be to start with an application of Sivanto at 4 oz/acre and follow with a different MOA as needed (e.g., Transform)

Being “OK” Doesn’t Always Cut It

Questions?