Title: Insecticide seed treatments compared to other management tact= ics for control of aphid vectors of Barley yellow dwarf virus

Title: Pl= anting date and foliar and seed applied insecticide treatments for control of aphid vec= tors of Barley yellow dwarf virus: 2006-2007.

Author: D= ouglas W. Johnson, Extension Entomologist, Univ. KY

STANDARD P= RACTICES

Experimental = Design^{[1]<=
/sup>
:} Split-Plot, with two planting dates, twenty four pesticide combinatio= ns, and three replications. All treatment were randomly experimental units using SAS Proc Plan.

Data Analysis= : Analysis of Variance (ANOVA) was conducted using SAS Proc GLM. Means separation was done using the Ryan-Einot-Gabriel-Welch test. SAS Inst. Inc., Cary, NC.

Experimental = Unit: 7, 7” rows by 20’ long.

Location:= UK-REC, Princeton, (Caldwell Co.) KY.,

Wheat Variety= =3D “Clark”

Seeding Rate:= 40 seeds / ft²

Tillage = =3D No-Till, following corn, flail mowing of stalks

Planting Equipment: Hege, No-till plot planter

&nb= sp;

N₂ Fertility: 1^{st=
–} 22 Feb 07, 40 lbs; 2nd App. – 22 Mar 07, 70 lbs

&nbs= p;

Herbicide: Harmone Extra @ &frac1= 2; oz / A on 09 Nov 06 & 16 Mar 07

Foliar Fungicide: Tilt @ 4 oz / A= . on 23 Apr 07.

&nbs= p;

Harvest:

Equipment: Wintersteiger plot combine

Harvest Date: 18 June 07.

&nbs= p;

EXPERIMENTAL TREATMENTS=

Planting Dates: 1^st Planting, Tue. Oct 3, 2006 2^nd Planting Mon Oct. 23, 2006.

Pesticides Tr= eatments / Rates:

Seed Treatments: Plots were planted with seed tr= eated with the following pesticides and rates. All seed applied treatments were made by product manufacturer or their designated applicator(s) at rates targeted for sale in Kentucky. Cruiser and Gaucho did not o= ccur in the test without their associated fungicide.

No Insecticide

Raxal/Thiram @ 3.5 oz. per 100wt.

Dividend E= xtream @ 2.0 oz. per 100wt.

Raxal/Thir= am + Gaucho @ 3.5 oz. + 1.0 oz. per 100wt.

Dividend E= xtream + Cruiser @ 2.0 oz. + 1.0 oz. per 100wt.

Foliar Treatments: <= span style=3D'mso-spacerun:yes'> Foliar treatments were made using a= CO₂ powered backpack sprayer, delivering 20 GPA, at 45 PSI, through 8003 nozzle= s. Plots may have received: No application,&n= bsp; a “Fall” application, a “Winter” application= or a “Fall” and “Winter” application .“Fall”= applications were applied thirty days after wheat emergence. For the first planting that= was 08 Nov. 06; for the second planting; 09 Dec 06. The “Winter” applicati= on was made on 08 Mar 07. All foliar insecticide applications consisted of : Warri= or @ 3.5 fl. oz. per acre.

Results

There is little doubt that planting date had a signifi= cant affect on the yield and test weight in the 2006-2007season (Table 1.). Anal= ysis clear shows that the second planting date resulted in greater yield and test weight. There were no interac= tions with other treatments.

This is = the normal occurrence, with planting after 15 Oct. generally having the advanta= ge. This advantage is often due to reduced exposure to the cereal aphid complex= and thus the yellow dwarf viruses, and possibly reduced Hessian fly infestation (thought Hessian fly is poorly understood in Kentucky). Conversely, in this season a major portion of the advantage is likely to be the result of differential damage suffered from a sever frost that occurred during April 6-9, 2007 (See Wheat Science News Vol. 11, No. 2 & other reports in this document). The week before the frost, plots planted on the 2nd planting date were signific= antly shorter than were those of the 1^st planting date. After the fros= t, plots planted on the 2^nd planting date were visually less damaged and appeared to recover more quickly and more completely. Certainly some of= he difference may be due BYD, but it is very difficult to estimate just how mu= ch.

Table 1. Ef= fect of planting date on yield and test weight of wheat plots on the UK-REC 2006-2007.
Planting Da= te	n	Yield ± S.E	Test Weight ± S.E=
03 Oct 2006	71	52.0 ± 1.2 b	60.6 &plu= smn; 0.2 b
23 Oct 2006	72	79.6 &plu= smn; 1.3 a	61.2 &plu= smn; 0.2 a
ANOVA	F(1,119)= =3D270.62, Pr>F=3D <.0001	F(1,119)= =3D 9.31, Pr>F=3D 0.0028
Means in the same column, follow by the same letter = are not significantly different using the Ryan-Einot-Gabriel-Welch mean separation test at p=3D0.05 level of significance.

In Kentu= cky, systemic insecticide seed treatments are only sold in combination with seed applied fungicides. In order = to understand whether or not the insecticides are having any affect on yield a= nd test weight, one must first separate the affects that may be due to the associated fungicide. Therefore the associated fungicides were tested separately. Table 2. indicates average yields and test weights for plot treated with seed applied fungicid= es compared to an untreated control. Analysis indicates that these fungicides did not produce any significant difference in yield or test weight compared to one another or the untreated control.

Table 2. Ef= fect of seed applied fungicide on yield and test weight of wheat plots on the UK-= REC 2006-2007.
Fungicide	N	Yield ± S.E (Bu / Ac)	Test Weight ± S.E.
None	48	63.3 &plu= smn; 2.4	60.7 &plu= smn; 0.2
Dividend Extreme	24	65.1 &plu= smn; 3.7	60.4 &plu= smn; 0.4
Raxal / Thiram	23	64.9 &plu= smn; 3.5	60.6 &plu= smn; 0.3
&nbs= p;	ANOVA; F(2,89)=3D 0.29, Pr>F =3D 0.7= 526	&nbs= p;

The affect of the systemic insecticide seed applied treatments is less straight forward. Analysis indicates that the insecticides did have an effect on yield (Table 3). Cruiser and Gaucho= both produced greater yields than did the untreated, but the two products were n= ot different from each other. ANOVA also, indicated significance among test weights. On the other hand, the difference could not be illustrated using a mean separation test. This indicates a very weak relationship to treatment.= Because there were no significant interactions, it is not possible to separate the differences that may be due to planting date. Arithmetically, however most = of the differences occurred in the first planting date, which is expected. In = the second planting date difference between the untreated and the two insectici= des was very small, though significant by definition. I have considerable doubt that these are real.

Table 3 Eff= ect of seed applied systemic insecticides on yield and test weight of wheat plot= s on the UK-REC 2006-2007.
Insecticide + (fungicide)	n	Yield &pl= usmn; S.E (Bu / Ac)=	Test Weig= ht ± S.E &nbs= p;
None + (none)	95	64.1 ± 1.7 b	60.6 &plu= smn; 0.2
Curiser + (dividend extream)	24	68.9 &plu= smn; 3.4 a	61.1 &plu= smn; 0.2
Gaucho + (raxal & thiram)	24	69.8 &plu= smn; 3.7 a	61.2 &plu= smn; 0.2
ANOVA	F(2,119)= =3D 6.87, Pr>F=3D 0.0015	F(2,119)= =3D 3.24, Pr>F=3D 0.0428
Means in the same colum= n, follow by the same letter are not significantly different using the Ryan-Einot-Gabriel-Welch mean separation test at p=3D0.05 level of significance.

The affect of foliar applications is shown in Table 4.= There was no significant affect on test weight, but some affects are seen in yiel= d. All the foliar applications are significantly different from the untreated.= The mean separation does not send a much more clear signal. The “Fall + Winter” is better than the “Fall” alone but not better th= an the “Winter” alone. Additionally, the “Winter” alone is not different from t= he “Fall”. As with t= he seed applied insecticides there was no there were no significant interactio= ns with planting date. It is therefore not possible to separate the differences that may be due to planting date. Again, arithmetically, most of the differences occurred in the first planting date, which is expected. In the second planting date difference between the untreated and the foliar insecticides was very small, though significant by definition. I have considerable doubt that these difference are real.

Table 4. Ef= fect of foliar applied insecticide at various timings on the yield and test weigh= t of wheat plots on the UK-REC 2006-2007.
Application= Timing	n	Yield ± S.E (Bu / Ac)	Test Weight ± S.E=
None	35	57.4 ± 2.9 c	60.9 &plu= smn; 0.3
Fall	36	65.1 ± 2.8 b	60.4 &plu= smn; 0.2
Fall + Winter	36	72.4 &plu= smn; 2.5a	61.0 &plu= smn; 0.2
Winter	36	68.5 ± 2.8 a b	60.8 &plu= smn; 0.2
ANOVA	&nbs= p;	F=3D(3,119) 15.34, Pr&g= t;F=3D <0.0001	F(3,119)=3D 0.38, Pr>= ;F=3D 0.07646
Means in the same colum= n, follow by the same letter are not significantly different using the Ryan-Einot-Gabriel-Welch mean separation test at p=3D0.05 level of significance.

Summery Interpretation

Certainly in the 2006-2007 season, planting date was t= he most important factor affecting yield and test weight in this experiment. Though there are likely differences due to aphids and associated BYD, the a= re far overshadowed by the planting date – frost interaction. Insecticides probably did provide = some differences particularly in the first planting, but it is highly unlikely t= hat they made much if any difference in the second planting.

References Ci= ted:

Wheat Science News. Vol. 11 No. 2. Apr. 2007. http://www.ca.uky.edu/ukrec/newsltrs/News07freeze.pdf

Acknowledgeme= nts

The author is wishes to acknowledge the Syngenta (Dr. = Scott Cully) and Bayer (Mr. Charles Graham) corporations for providing the seed applied insecticides and getting the seed treated at their facilities. Addi= tionally, I wish to thank, Mr. Bill Bruening, Ms. Dottie Call, Mr. John James and Mr. Charles Tutt (Plant & Soil Sciences) for help with the agronomic portio= ns of this study. I also, express my gratitude to Ms. Stephanie Farmer for aid= in preparation of this manuscript.