2008 AU Crops

Soybean Research Report

Research Report No. 34 May 2009 Alabama Agricultural Experiment Station Richard Guthrie, Director Auburn University Auburn, Alabama
Printed in cooperation with the Alabama Cooperative Extension System (Alabama A&M University and Auburn University)

ACKNOWLEDGMENTS
This publication is a joint contribution of Auburn University, the Alabama Agricultural Experiment Station, and the USDA Agricultural Research Service and Soil Dynamics Laboratory. Research contained in the AU crops research reports was partially funded through the Alabama Cotton Commission, the Wheat and Feed Grains Committee, the Alabama Soybean Producers, and private industry grants. All donations, including the Alabama Cotton Commission grants and private industry funding, are appreciated.

CONFIDENTIAL REPORT
Publication, display, or distribution of data contained herein should not be made without prior written approval. Mention of a trademark or product does not constitute a guarantee of the product by Auburn University and does not imply its approval to the exclusion of other products.

This report can be found on the Web at http://www.ag.auburn.edu/aaes/communications/researchreports/08soybeanrr.pdf

Information contained herein is available to all persons regardless of race, color, sex, or national origin.

Published by the Alabama Cooperative Extension System (Alabama A&M and Auburn universities) in cooperation with the U.S. Department of Agriculture. An equal opportunity educator and employer.

CONTENTS
page Editors, Contributors ...........................................................................................................................................................................4

VARIETY TRIALS
MG VI and VII Roundup Ready® Soybean Varieties, High pH Soils, Dallas County, Alabama, 2008 .............................................5 Irrigated MG V to VII Roundup Ready® Soybean Varieties, Barbour County, Alabama, 2008 .........................................................6 Irrigated MG V to VII Roundup Ready® Soybean Varieties, Escambia County, Alabama, 2008 ......................................................7

DISEASE MANAGEMENT
Strobiluron Fungicide Greening Effects on Soybeans at Crossville, 2008 .........................................................................................8 Strobiluron Fungicide Greening Effects on Soybeans at Belle Mina, 2008 .......................................................................................9 Strobiluron Fungicide Greening Effects on Soybeans at Shorter, 2008 ...........................................................................................10

WEED MANAGEMENT
Late Glyphosate Applications on Soybeans at Belle Mina, 2008 .....................................................................................................11 Late Glyphosate Applications on Soybeans at Crossville, 2008.......................................................................................................12 Evaluation of Foliar Fungicides for Soybean Rust Management and Yield in South Alabama, 2008 .............................................13 Soybean Rust Management and Yield Affects in South Alabama ....................................................................................................14 Soybean Rust Fungicide Disease Management and Yield Affects in Alabama ................................................................................15 Evaluation of Avicta® Seed Treatments for Reniform Nematode Management in Soybean in South Alabama, 2008.....................16 Contributors Index ............................................................................................................................................................................17

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ALABAMA AGRICULTURAL EXPERIMENT STATION

EDITORS

K. S. Lawrence Associate Professor Entomology and Plant Pathology Auburn University

C. D. Monks Professor and Extension Agronomist Agronomy and Soils Auburn University

D. P. Delaney Extension Specialist IV Agronomy and Soils Auburn University

CONTRIBUTORS
J. R. Akridge Director Brewton Agricultural Research Unit Brewton, Alabama W. C. Birdsong Regional Agronomist Southeast Alabama Alabama Cooperative Extension System T. Dawkins Director Sand Mountain Research and Extension Center, Crossville, Alabama D. P. Delaney Extension Specialist IV Agronomy and Soils, Auburn University B. Dillard Regional Extension Agent, Southeast Alabama Alabama Cooperative Extension System J. Ducar Associate Director Sand Mountain Research and Extension Center Crossville, Alabama B. Durbin Director, Field Crops Unit E.V. Smith Research Center Shorter, Alabama D. H. Harkins Assistant Director Tennessee Valley Research and Extension Center Belle Mina, Alabama J. Jones Assistant Director Gulf Coast Research and Extension Center Fairhope, Alabama G. W. Lawrence Entomology and Plant Pathology Mississippi State University K. S. Lawrence Associate Professor Entomology and Plant Pathology Auburn University S. R. Moore Graduate Research Assistant Entomology and Plant Pathology Auburn University B. E. Norris Director Tennessee Valley Research and Extension Center Belle Mina, Alabama M. Pegues Associate Director Gulf Coast Research and Extension Center Fairhope, Alabama R. Petcher Regional Extension Agent, Southwest Alabama Alabama Cooperative Extension System E. J. Sikora Professor Entomology and Plant Pathology Auburn University R. P. Yates Regional Extension Agent, West Central Alabama Alabama Cooperative Extension System

2008 AU CROPS: SOYBEAN RESEARCH REPORT

5

VARIETY TRIALS
MG VI AND VII ROUNDUP READY® SOYBEAN VARIETIES, HIGH PH SOILS, DALLAS COUNTY, ALABAMA, 2008
D. P. Delaney and R. P. Yates

This trial was planted on June 19, 2008 following a wheat grain crop on the Sam Givhan Farm near Safford, Alabama. Each cultivar was planted in a single, field-length strip 15 to 25 feet wide approximately 1500 feet long. Soil type was a Leeper silty clay with a pH of 7.8 to 8.0 Rows were spaced 20 inches apart with a no-till planter equipped with row cleaners. A windstorm had severely lodged the wheat straw, causing difficult planting conditions and poor stands in some strips across the field. Plots

were maintained according to Alabama Cooperative Extension System recommendations. Plots were harvested on October 29, 2008 with the producers’ combine and a weighing grain buggy. No significant lodging was noted for any variety. Yields were adjusted to 13 percent moisture and 60 pounds per bushel. While early summer rainfall was generally good, dry weather during pod fill impacted yields. Some yellowing from iron chlorosis was observed and was rated on August 20 (see table).

Variety

MG VI AND VII RR SOYBEAN VARIETIES ON HIGH PH SOILS, DALLAS COUNTY, 2008
Yield1 bu/A 26.5 24.2 22.3 21.7 18.9 18.1 1 2 1 3 1 1

Chlorosis2

DeltaPine 6880 RR DeltaPine 6568 RR Asgrow 6702 RR DeKalb- DKB 64-51 RR Pioneer 96M60 (RR) Asgrow 6301 RR
1 2

Adjusted to 13 percent moisture and 60 pounds per bushel. Rated 20 Aug: 1 = green, 5 = very yellow.

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ALABAMA AGRICULTURAL EXPERIMENT STATION

IRRIGATED MG V TO VII ROUNDUP READY® SOYBEAN VARIETIES, BARBOUR COUNTY, ALABAMA, 2008
D. P. Delaney, B. Dillard, W. C. Birdsong, and K. S. Lawrence

This trial was planted on May 5, 2008 on the Walt and Tom Corcoran Farm near Eufaula, Alabama. Four replications of each variety were planted in a randomized complete block pattern. Each plot was 19 feet wide and 900 to 1100 feet long with a twin-row pattern (38-inch main centers) used at planting. Soil type was a Dothan fine sandy loam with corn planted in 2007. Plots were irrigated and maintained according to Alabama Co-

operative Extension System recommendations. Samples of roots and soil for root-knot nematodes were taken from each plot on October 3. There were no significant differences in root galling between plots, and nematodes were below detectable levels at the time of sampling. Plots were harvested on October 28, 2008 using the producers’ combine and a weighing grain buggy. No significant lodging was noted for any variety. Yields were adjusted to 13 percent moisture and 60 pounds per bushel.

Variety

IRRIGATED MG V TO VII RR SOYBEAN VARIETIES, BARBOUR COUNTY, 2008
Advertised maturity 7.5 6.7 7.3 7.3 7.3 7.5 5.9 7.4 Yield1 bu/A 70.2 70.2 67.6 65.7 63.9 63.3 59.5 57.5 4.2

Asgrow 7501 RR Asgrow 6702 RR DeltaPine 7330 RR2 Dyna-Gro 35K73 RR Croplan RC 7355 RR Pioneer 97M50 (RR) DeltaPine 5914 RR2 Dyna-Gro 32R74 RR LSD (P = 0.10)
1 2

Adjusted to 13 percent moisture and 60 pounds per bushel. Due to limited seed at planting, only two replications were planted for these two varieties.

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IRRIGATED MG V TO VII ROUNDUP READY® SOYBEAN VARIETIES, ESCAMBIA COUNTY, ALABAMA, 2008
D. P. Delaney and R. Petcher

This trial was planted on June 18, 2008 following a wheat grain crop on the Bennie and Matt Watson Farm near Atmore, Alabama. Each cultivar was planted in a single block 36 feet wide and 725 feet long in 7.5-inch rows using a grain drill. Plots

were maintained according to Alabama Cooperative Extension System recommendations. Plots were harvested on November 6, 2008 using the producers’ combine and a weighing grain buggy. No significant lodging was noted for any variety. Yields were adjusted to 13 percent moisture and 60 pounds per bushel.

Variety

MG V TO VII RR SOYBEAN VARIETIES, ESCAMBIA COUNTY, 2008
Yield1 buA 58.8 58.5 57.4 56.8 56.0 55.8 55.7 55.2 55.1 54.1 53.7 53.1 52.8 51.9 51.9

NK S 74-W6 RR NK S 78-G6 RR Asgrow 7601 RR Asgrow 6702 RR Asgrow - DeKalb 6301 RR DeKalb- DKB 64-51 RR Pioneer 96M60 (RR) NK S 65-M3 RR Terral 59R16 RR Dyna-Gro 35K73v Terral 55R15v NK S 61-Q2 RR NK S 68-D4 RR NK S 80-P2 RR DeltaPine 6568 RR
1

Adjusted to 13 percent moisture and 60 pounds per bushel.

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ALABAMA AGRICULTURAL EXPERIMENT STATION

DISEASE MANAGEMENT
STROBILURON FUNGICIDE GREENING EFFECTS ON SOYBEANS AT CROSSVILLE, 2008
D. P. Delaney, E. J. Sikora, T. Dawkins, and J. Ducar

Many producers have noted retention of green leaves after pod maturity where strobiluron fungicides have been applied, leading to seed deterioration, shattering losses, and greatly reduced speeds with increased fuel and machinery costs and foreign material dockage. This problem has been linked to plant physiological changes and secondary disease control accompanying the use of strobiluron fungicides. This trial at the Sand Mountain Research and Extension Center (SMREC) investigated the use of three strobiluroncontaining fungicides (see table) applied at two growth stages. Dyna-Gro 3443nRR soybean seed was planted on May 2 in a Wynville sandy loam using strip-tillage, and managed according to Alabama Cooperative Extension System recommendations. Plots were four 36-inch rows, 25 feet long, arranged in a randomized complete block design with four replications. The three fungicides were applied in a factorial design at either the R2 growth stage (full bloom) on June 26, or the R2 + R5 (begin-

ning seed fill) growth stage on July 17. Fungicides were applied in 20 gallons per acre of water using a backpack CO2 sprayer equipped with TeeJet 8002VS flat fan nozzles on 19-inch centers at 55 psi. Per resistance management guidelines, a triazole fungicide (Folicur at a rate of 3 fluid ounces per acre) was added to the second strobiluron spray of Headline and Quadris. (Stratego is a premix containing a strobiluron and a triazole.) The trial was rated at pod maturity, with ratings on September 17 and 26. The center two rows of each plot were harvested with a plot combine on September 30 and weighed with samples dried and analyzed for seed weights. (see table). Fungicide applications at R2 + R5 compared to R2 alone or the untreated check increased retention of green leaves at both rating dates. Fungicide applications at R2 + R5 compared to R2 alone or the untreated check also increased yields (27.5 versus 25.6 bushels per acre) and 100-seed weights (13.4 versus 13.1 grams) with no significant interactions between treatments and application timing.

STROBILURON EFFECT ON SOYBEAN YIELD WHEN APPLIED AT DIFFERENT TIMINGS, SMREC, 2008
Treatment (Rate) Headline (9 oz/A) Headline (9 oz/A) Quadris (9 oz/A) Quadris (9 oz/A) Stratego (10 oz/A) Stratego (10 oz/A) Untreated check LSD (0.10)
1

Timing R2 only R2 + R5 R2 only R2 + R5 R2 R2 + R5

—Greening1— 17 Sep 26 Sep 8.8 9.3 7.5 7.8 9.0 9.3 8.5 8.8 9.3 9.3 8.5 8.8 9.5 9.8 0.9 0.8

Yield 100-seed bu/A grams 26.6 13.2 26.7 14.0 24.6 13.3 28.4 13.3 25.7 12.8 27.5 13.0 25.6 12.7 2.4 0.6

Greening rating: 1 = lush green, 10 = brown and dry.

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STROBILURON FUNGICIDE GREENING EFFECTS ON SOYBEANS AT BELLE MINA, 2008
D. P. Delaney, E. J. Sikora, B. E. Norris, and D. Harkins

Many producers have noted retention of green leaves after pod maturity where strobiluron fungicides have been applied, leading to seed deterioration, shattering losses, and greatly reduced harvest speeds with increased fuel and machinery costs and foreign material dockage. This problem has been linked to plant physiological changes and secondary disease control accompanying the use of strobiluron fungicides. This trial at the Tennessee Valley Research and Extension Center (TVREC) investigated the use of three strobiluron-containing fungicides (see table) applied at two growth stages. DeltaKing 5068 RR soybean seed was planted on May 7 in a Decatur silt loam, and managed according to Alabama Cooperative Extension System recommendations. Plots were four 30-inch rows, 30 feet long, arranged in a randomized complete block design with four replications. Three fungicides were applied in a factorial design at either the R2 growth stage (full bloom) on July 3, or the R2 + R5 (beginning seed fill) growth stage on July

25. Fungicides were applied in 20 gallons per acre of water using a backpack CO2 sprayer equipped with TeeJet 8002VS flat fan nozzles on 19-inch centers at 60 psi. Per disease resistance management guidelines, a triazole fungicide (Folicur at a rate of 3 fluid ounces per acre) was added to the second strobiluron spray of Headline and Quadris. (Stratego is a premix containing a strobiluron and a triazole.) The trial was rated at pod maturity, with ratings at approximately 60 percent brown pods on October 2. The center two rows of each plot were harvested with a plot combine on October 22 and weighed, with samples dried and analyzed for seed weights (see table). Retention of green leaves was increased by all fungicide applications, with R2 +R5 greater than R2 alone with no interactions between treatments and timing. Yields were not affected by strobiluron fungicide applications, while 100-seed weights were slightly increased by both Headline applications as well as Quadris at R2 only.

STROBILURON EFFECT ON SOYBEAN YIELD WHEN APPLIED AT DIFFERENT TIMINGS, TVREC, 2008
Treatment (Rate) Headline (9 oz/A) Headline (9 oz/A) Quadris (9 oz/A) Quadris (9 oz/A) Stratego (10 oz/A) Stratego (10 oz/A) Untreated check LSD (0.10)
1

Timing R2 only R2 + R5 R2 only R2 + R5 R2 R2 + R5

Greening1 3 Oct 5.8 5.5 6.3 6.0 6.5 5.8 7.8 0.7

Yield bu/A 51.4 48.7 54.1 56.9 54.6 54.1 48.6 85

100-seed grams 16.7 16.7 16.5 16.2 15.9 16.2 15.6 0.8

Greening rating: 1 = lush green, 10 = brown and dry.

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ALABAMA AGRICULTURAL EXPERIMENT STATION

STROBILURON FUNGICIDE GREENING EFFECTS ON SOYBEANS AT SHORTER, 2008
D. P. Delaney, E. J. Sikora, and B. Durbin

Many producers have noted retention of green leaves after pod maturity where strobiluron fungicides have been applied, leading to seed deterioration, shattering losses, and greatly reduced harvest speeds with increased fuel and machinery costs and foreign material dockage. This problem has been linked to plant physiological changes and secondary disease control accompanying the use of strobiluron fungicides. This trial the E.V. Smith Field Crops Unit (EVS) investigated the use of three strobiluron-containing fungicides (see table) applied at two growth stages. Pioneer 94M80 (RR) soybean seed was planted on April 24 at 10 seed per foot in a Compass loamy sand, and managed according to Alabama Cooperative Extension System recommendations. Plots were four 36-inch rows, 25 feet long, arranged in a randomized complete block design with four replications. Three fungicides were applied in a factorial design at either the R2 growth stage (full bloom) on June 23, or the R2 + R5 (beginning seed fill) growth stage on July 15. Fungicides were applied in 18 gallons per acre of water using a Lee Spider high clearance sprayer with Turbodrop TDXL 10002 flat

fan nozzles on 20-inch centers at 60 psi. Per disease resistance management guidelines, a triazole fungicide (Folicur at a rate of 3 fluid ounces per acre) was added to the second strobiluron spray of Headline and Quadris. (Stratego is a premix containing a strobiluron and a triazole.) The trial was rated at pod maturity, with ratings at approximately 60 percent brown pods and again just prior to harvest. The center two rows were harvested with a plot combine, weighed before and after drying, and samples taken for seed weights (see table). Retention of green leaves was increased at the first rating by all fungicide applications compared to the check, with Quadris greater than Stratego (6.9 versus 5.4) and R2 + R5 greater than R2 alone (6.8 versus 5.8) with no interactions between treatments and timing. At the second rating, greening was again increased by fungicides: Headline and Quadris had greater greening than Stratego (5.6 and 5.4 versus 4.0, respectively), with R2 +R5 greater than R2 alone (5.3 versus 4.7) with no interactions. Yields and 100-seed weights were not affected by strobiluron fungicide applications.

STROBILURON EFFECT ON SOYBEAN YIELD WHEN APPLIED AT DIFFERENT TIMINGS, EVS, 2008
Treatment (Rate) Headline (9 oz/A) Headline (9 oz/A) Quadris (9 oz/A) Quadris (9 oz/A) Stratego (10 oz/A) Stratego (10 oz/A) Untreated check LSD (0.10)
1

–Greening1– Timing 3 Sep 8 Sep R2 only 6.3 5.5 R2 + R5 7.0 5.8 R2 only 6.3 4.8 R2 + R5 7.5 6.0 R2 5.0 3.8 R2 + R5 5.8 4.3 3.3 2.5 1.2 1.0

Yield 100-seed bu/A grams 49.0 15.6 48.0 15.8 49.4 15.5 50.8 16.0 53.0 15.4 49.5 15.8 51.2 15.3 4.1 0.7

Greening rating: 10 = lush green, 1 = brown and dry.

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WEED MANAGEMENT
LATE GLYPHOSATE APPLICATIONS ON SOYBEANS AT BELLE MINA, 2008
D. P. Delaney, E. J. Sikora, B. E. Norris, and D. Harkins

Many soybean producers in Alabama use a glyphosatebased weed control system using Roundup Ready soybeans, with many relying entirely on postemergence applications for weed control. Although there is the potential for yield loss with late applications (postbloom), many producers are faced with escaped weeds late in the season, and apply glyphosate over-thetop later than recommended. The potential for yield loss with late applications under Alabama conditions has not been clearly documented. The objective of this trial was to evaluate the use of late applications of glyphosate on soybean yield. This trial at the Tennessee Valley Research and Extension Center investigated the use of two rates of glyphosate (one and two times the normal rates) at two postbloom growth stages. DeltaKing 5068 RR was planted on May 7 in a Decatur silt loam, and managed according to Alabama Cooperative Extension System recommendations. Plots were four 30-inch rows, 30

feet long, arranged in a randomized complete block design with four replications. Roundup WeatherMax (5.5 pounds per gallon glyphosate) applications were applied in a factorial design at either the R3 or R5 growth stages at 22 or 44 fluid ounces per acre. R4 growth stage (full-size pod stage) applications were made on July 25, while R5 (beginning seed fill) growth stage applications were made on July 31. Herbicides were applied in 20 gallons per acre of water using a backpack CO2 sprayer equipped with TeeJet 8002VS flat fan nozzles on 19-inch centers at 55 psi. The center two rows were harvested with a plot combine on October 22, weighed, and sampled for seed weights. Plant growth and yields were limited by dry weather, with no significant differences between treatments or factors for yield or 100-seed weight (see table).

SOYBEAN YIELDS AND 100-SEED WEIGHTS AFTER GLYPHOSATE APPLICATION AT THE R3 AND R5 GROWTH STAGES, TVREC, 2008
Treatment Untreated check Roundup WeatherMax Roundup WeatherMax Roundup WeatherMax Roundup WeatherMax LSD (P=.10) Rate 22 oz/A 22 oz/A 44 oz/A 44 oz/A Stage R4 R5 R4 R5 Yield 100-seed bu/A grams 49.9 14.2 49.8 14.9 48.1 14.6 50.4 15.1 49.5 14.8 NS NS

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ALABAMA AGRICULTURAL EXPERIMENT STATION

LATE GLYPHOSATE APPLICATIONS ON SOYBEANS AT CROSSVILLE, 2008
D. P. Delaney, E. J. Sikora, T. Dawkins, and J. Ducar

Many soybean producers in Alabama use a glyphosatebased weed control system using Roundup Ready soybeans, with many relying entirely on postemergence applications for weed control. Although there is the potential for yield loss with late applications (postbloom), many producers are faced with escaped weeds late in the season, and apply glyphosate over-thetop later than recommended. The potential for yield loss with late applications under Alabama conditions has not been clearly documented. The objective of this trial was to evaluate the use of late applications of glyphosate on soybean yield. This trial at the Sand Mountain Research and Extension Center investigated the use of two rates of glyphosate (one time and two times normal rates) at two postbloom growth stages. Dyna-Gro 3443nRR was planted on May 2 using strip tillage in a Wynnville sandy loam, and managed according to Alabama

Cooperative Extension System recommendations. Plots were four 36-inch rows, 25 feet long, arranged in a randomized complete block design with four replications. Roundup WeatherMax (5.5 pounds per gallon glyphosate) applications were applied in a factorial design at either the R3 or R5 growth stages at 22 or 44 fluid ounces per acre. R3 growth stage (3/16-inch pod stage) applications were made on July 17, while R5 (beginning seed fill) growth stage applications were made on July 29. Herbicides were applied in 20 gallons per acre of water using a backpack CO2 sprayer equipped with TeeJet 8002VS flat fan nozzles on 19-inch centers at 55 psi. The center two rows were harvested on September 30 with a plot combine, weighed, and sampled for seed weights. Plant growth and yields were limited by extremely dry weather, with no significant differences between treatments or factors for yield or 100-seed weight (see table).

SOYBEAN YIELDS AND 100-SEED WEIGHTS AFTER GLYPHOSATE APPLICATION AT THE R3 AND R5 GROWTH STAGES, SMREC, 2008
Treatment Untreated check Roundup WeatherMax Roundup WeatherMax Roundup WeatherMax Roundup WeatherMax LSD (P=.10) Rate 22 oz/A 22 oz/A 44 oz/A 44 oz/A Stage R3 R5 R3 R5 Yield bu/A 18.7 18.6 16.9 17.8 17.5 NS

100-seed grams 13.1 12.8 12.9 13.0 13.0 NS

2008 AU CROPS: SOYBEAN RESEARCH REPORT

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EVALUATION OF FOLIAR FUNGICIDES FOR SOYBEAN RUST MANAGEMENT AND YIELD IN SOUTH ALABAMA, 2008
K. S. Lawrence, E. J. Sikora, D. P. Delaney, G. W. Lawrence, J. Jones, and M. Pegues

A soybean fungicide trial was planted on June 9 at the Auburn University Gulf Coast Research and Education Center at Fairhope, Alabama. The variety selected was DP 7870 RR and the soil type was a Malbis fine sandy loam. Plots were four rows, 25 feet long, with a row spacing of 38 inches. Plots were arranged in a randomized complete-block design with four replications. The fungicide treatments were applied as a foliar spray at the R3 and R5 plant growth stages. Fungicides were applied in 18 gallons per acre of water using a Lee Spider high clearance sprayer with Turbodrop TDXL 10002 flat fan nozzles on 20-inch centers at 60 psi. Soybean foliar diseases were evaluated by rating severity of each disease in the plot at the R6 to R7 growth stage. All plots were maintained throughout the season with standard herbicide, insecticide, and fertility production practices as recommended by the Alabama Cooperative Extension System. Plots were harvested on November 19. Data were statistically analyzed using the general linear models procedure (PROC GLM) in SAS, and means were compared with Fisher’s protected least significant difference test (P ≤ 0.10). Weather conditions were favorable for moderate incidence of foliar disease on soybean with 22.3, 7.6, 13.5, 33.1, and 17.9

inches of rainfall in May through September, respectively. Soybean rust leaf symptoms were first observed in the lower leaf canopy of the untreated control plots in mid-September at the R6 full seed growth stage. Rust severity was greater in the untreated control as compared to all of the fungicide treatments (P ≤ 0.10). Two weeks later on September 24, soybean plants had matured to the R7 growth stage. Rust severity had increased in most treatments but continued to be significantly more severe (P ≤ 0.10) in the untreated control as compared to the fungicide treatments. Punch 3.3 EC and Headline 3.3 ED produced the lowest severity ratings numerically. Picoxystrobin rust incidence was not affected by the increased rate from 6 to 12 fluid ounces per acre. The reduction of rust with the fungicide treatments also increased soybean yield. Headline 3.3 ED (9) Punch 3.3 EC + Headline 3.3 ED (7), and LEM17 SC 9.6 fluid ounces per acre (1) produced greater yields (P ≤ 0.10) than the untreated control. These treatments increased yields by an average of 2.9 bushels per acre. However, all fungicide treatments numerically increased yield over the untreated control. Rust developed later in the season this year, which is likely the reason the yields were not as severely reduced as compared to soybean yields in 2007.

FOLIAR FUNGICIDE EFFECT ON SOYBEAN RUST SEVERITY AND YIELD
Treatment 1 LEM17 SC 2 LEM17 SC 3 LEM17 SC Punch 3.3 EC 4 Picoxystrobin 5 Picoxystrobin 6 Picoxystrobin 7 Punch 3.3 EC Headline 2.09 EC 8 Punch 3.3 EC 9 Headline 3.3 EC 10 Untreated control LSD P ≤ 0.10
1

Rate/A 9.6 fl oz 16.8 fl oz 9.6 fl oz + 3 fl oz 6 fl oz 8 fl oz 12 fl oz 3 fl oz + 4.5 fl oz 3 fl oz 4.5 fl oz

Growth stage R3 + R5 R3 + R5

—Soybean rust severity1— 10 Sep 24 Sep 2.6 b 3.4 b 2.4 b 3.0 b 2.6 b 2.4 b 2.4 b 2.6 b 2.4 b 2.4 b 2.0 b 4.0 a 0.5 2.6 b 2.6 b 2.8 b 2.6 b 2.6 b 2.0 b 2.0 b 5.0 a 0.9

Yield bu/A 45.8 a 44.9 ab 43.7 ab 43.7 ab 42.9 b 43.8 ab 45.7 a 44.3 ab 45.4 a 42.7 b 2.52

R3 + R5 R3 + R5 R3 + R5 R3 + R5 R3 + R5 R3 + R5

Disease severity: 1= no rust; 2 < 2.5%, 3 = 2.5 - 5%, 4 = 5 - 10%, 5 = 10 - 15%, 6 = 15- 25%, 7 = 25 35%, 8 = 35 - 67%, 9 = 67- 100%. Means within columns followed by different letters are significantly different according to Fisher’s LSD (P ≤ 0. 10).

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ALABAMA AGRICULTURAL EXPERIMENT STATION

SOYBEAN RUST MANAGEMENT AND YIELD AFFECTS IN SOUTH ALABAMA
K. S. Lawrence, E. J. Sikora, D. P. Delaney, J. Jones, and M. Pegues

A soybean fungicide trial was planted with DP 7870 RR soybean seed on June 9 at the Auburn University Gulf Coast Research and Extension Center at Fairhope, Alabama. The soil type was a Malbis fine sandy loam. Plots were four rows, 25 feet long, with a row spacing of 38 inches. Plots were arranged in a randomized complete-block design with four replications. The fungicide treatments were applied as a foliar spray at the R3 (August 19) plant growth stage. Fungicides were applied in 18 gallons per acre of water using a Lee Spider high clearance sprayer with Turbodrop TDXL 10002 flat fan nozzles on 20inch centers at 60 psi. Soybean foliar diseases were evaluated by rating disease severity at the R6 to R7 growth stage. All plots were maintained throughout the season with standard herbicide, insecticide, and fertility production practices as recommended by the Alabama Cooperative Extension System. Plots were harvested on November 19. Data were statistically analyzed using the general linear models procedure (PROC GLM) in SAS, and means were compared with Fisher’s protected least significant difference test (P ≤ 0.10). Weather conditions were favorable for moderate incidence of foliar disease on soybean with 9.3, 3.3, 5.4, 14.1 7.7, and 4.1

inches of rainfall in May through September, respectively. Soybean rust leaf symptoms were first observed in mid September on the lower leaf canopy of the untreated control plots. Rust severity on October 1 was greater in the untreated control (1), Tebuzol (2), and KFD-21-03 (4) as compared to all of the other fungicide treatments (P ≤ 0.10). By October 9 rust severity in the control was up to 25 to 35 percent which was higher than all the fungicide treatments. Topguard (7) and Domark applied at 4 and 5 fluid ounces per acre (8 and 9) further suppressed rust severity to less than 2.5 percent which was less than (P ≤ 0.10) all other fungicide treatments. The Topguard and Domark treatments continued to suppress rust through the last rating on October 16 as compared to Tebuzol (2), Topsin M (3), KFD-2103 (4), Topsin M + Tebuzol (5) and Headline (6). Defoliation was also reduced in the Topguard (7) Domark (8 and 9) and the Topsin M + Tebuzol combination (5) as compared to all other treatments and the control. Yields were affected by prolonged wet soil conditions during pod-fill, as well as green stems interfering with timely and efficient harvesting. All fungicide treatments produced similar yields with an average increase of 2.7 bushels per acre over the control.

EFFECT OF FOLIAR FUNGICIDES ON SOYBEAN RUST SEVERITY, DEFOLIATION, AND YIELD
1 2 3 4 5 6 7 8 9
1

Treatment Untreated check Tebuzol Topsin M KFD-21-03 Topsin M Tebuzol Headline Topguard Domark Domark LSD ≤ 0.10 CV

Rate/A 4 fl oz 16 fl oz 20 fl oz 16 fl oz 4 fl oz 6 fl oz 7 fl oz 4 fl oz 5 fl oz

Timing R3 R3 R3 R3 R3 R3 R3 R3 R3

————————Rust severity1——————— 16 Sep 1 Oct 9 Oct 16 Oct 0.10 a 5.4 a 7.28 a 8.0 a 0.00 b 3.4 a 4.80 b 7.5 ab 0.00 b 1.4 b 4.45 b 7.4 ab 0.00 b 4.4 a 4.39 b 6.8 ab 0.00 b 0.4 b 2.80 b 6.4 b 0.4 b 0.0 b 0.1 b 0.0 b 2.0 76.5 3.72 b 0.13 c 0.48 c 0.00 c 2.1 54.7 7.1 ab 0.7 d 2.0 c 1.3 cd 1.2 18.1

Defoliation (%) 16 Oct 90.3 a 82.8 ab 61.8 c 73.0 abc 35.0 d 63.9 bc 19.3 d 28.0 d 28.5 d 19.0 29.0

Yield bu/A 31.1 a 33.4 a 34.7 a 32.5 a 34.9 a 33.5 a 34.6 a 34.4 a 32.7 a 4.8 11.5

0.03 b 0.00 b 0.00 b 0.00 b 0.0 234.7

Rust severity: 1= no rust; 2 < 2.5%, 3 = 2.5 - 5%, 4 = 5 - 10%, 5 = 10 - 15%, 6 = 15- 25%, 7 = 25 - 35%, 8 = 35 - 67%, 9 = 67- 100%. Means within columns followed by different letters are significantly different according to Fisher’s LSD (P ≤ 0.10).

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2008 AU CROPS: SOYBEAN RESEARCH REPORT

15

SOYBEAN RUST FUNGICIDE DISEASE MANAGEMENT AND YIELD AFFECTS IN ALABAMA
K. S. Lawrence, E. J. Sikora, D. P. Delaney, J. Jones, and M. Pegues

A soybean fungicide trial was planted with DP 7870 RR soybeans on June 9 at the Auburn University Gulf Coast Research and Extension Center at Fairhope, Alabama. The variety selected was DP 7870 RR and the soil type was a Malbis fine sandy loam. Plots were four rows, 25 feet long, with a row spacing of 38 inches. Plots were arranged in a randomized completeblock design with four replications.The fungicide treatments were applied as a foliar spray on August 19 at R3 and again 10 days later. Fungicides were applied in 18 gallons per acre of water using a Lee Spider high clearance sprayer with Turbodrop TDXL 10002 flat fan nozzles on 20-inch centers at 60 psi. Soybean foliar diseases were evaluated by rating disease severity at the R6 to R7 growth stage. All plots were maintained throughout the season with standard herbicide, insecticide, and fertility production practices as recommended by the Alabama Cooperative Extension System. Plots were harvested on November 19. Data were statistically analyzed using the general linear models procedure (PROC GLM) in SAS, and means were compared with Fisher’s protected least significant difference test (P ≤ 0.10). Weather conditions were favorable for moderate incidence of foliar disease on soybean with 9.3, 3.3, 5.4, 14.1, 7.7, and 4.1 inches of rainfall in May through September, respectively.

Soybean rust leaf symptoms were first observed in mid September on the lower leaf canopy of the untreated control plots and rating were begun on October 1 at the R7 full seed growth stage. Rust severity was greater in the untreated control (13), Quadris (2), and Alto (6) as compared to all of the other fungicide treatments (P ≤ 0.10). By October 9, Topguard applied at R3 or R5 and Domark applied at R5 suppressed rust severity more than (P ≤ 0.10) all other fungicide treatments. The Topguard treatment applied at R5 continued to suppress rust severity through October 16. Defoliation ranged from 36.8 to 97.5 percent with the eight fungicide treatments reducing leaf senescence (P ≤ 0.10) as compared to the control. Yields were affected by prolonged wet soil conditions during pod-fill, as well as green stems interfering with timely and efficient harvesting. Six fungicide treatments increased yields over the untreated control. Topguard (11), Domark (12), and Stratego (14) all applied at R3 +10 and Domark (3), Folicur (7), and Stratego + Proline (8) applied at R3 produced greater yields (P ≤ 0.10) than the control. All fungicide treatment yields averaged together indicate the use of a fungicide increased yields by 4.7 bushels per acre over the untreated control.

EFFECT OF FOLIAR FUNGICIDES ON SOYBEAN RUST SEVERITY, DEFOLIATION, AND YIELD
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1

Treatment Headline 3.3 EC Quadris Domark Topguard Punch + Picoxystrobin Alto 100 Folicur Stratego + Proline Quadris + Alto 100 4.0 fl oz Headline 3.3 EC + Folicur Topguard Domark Untreated control Stratego LSD (P ≤ 0.10) CV

Rate/A 6.0 fl oz 6 fl oz 5 fl oz 7.0 fl oz 4 fl oz + 6 fl oz 4.0 fl oz 4.0 fl oz 10 fl oz + 1 fl oz 6 fl oz + 4.5 fl oz + 4 fl oz 7.0 fl oz 5 fl oz 10 fl oz

Growth stage R3 R3 R3 R3 R3 R3 R3

——Soybean rust severity1—— 1 Oct 9 Oct 16 Oct 3.4 b 5.9 bc 7.5 a 6.4 a 7.6 a 7.3 a 0.1 c 1.8 d 4.9 cd 0.0 c 0.1 e 5.0 cd 1.6 c 4.8 b 1.1 c 1.1 c 0.7 c 0.4 c 4.7 c 6.8 ab 5.1 c 4.7 c 2.0 d 2.3 d 0.1 e 0.2 e 7.9 a 3.1 d 1.5 33.3

Defoliation (%) 16 Oct 77.5 a-d 92.3 ab 69.0 b-e 36.8 f 58.5 c-f 79.0 abc 79.0 abc 74.1 a-e 37.5 f 53.0 def 51.5 ef 40.8 f 97.5 a 70.3 b-e 51.5 40.8

Yield bu/A 35.5 ab 29.0 bc 39.7 a 36.5 ab 33.7 bc 31.1 bc 39.5 a 40.2 a 33.1 bc 35.4 ab 39.5 a 39.6 a 31.5 bc 37.9 a 6.3 14.8

7.1 ab 6.6 abc 6.3 abc 5.4 de 4.0 de 5.0 cd 2.7 e 4.5 d 7.1 ab 5.3 cd 1.6 23.4

R3 + R5 R3 + R3 +10 R3 +10 R3 +10 R3+10

0.2 c 0.4 c 7.5 a 1.2 c 1.5 61.5

Rust severity: 1= no rust; 2 < 2.5%, 3 = 2.5 - 5%, 4 = 5 - 10%, 5 = 10 - 15%, 6 = 15- 25%, 7 = 25 - 35%, 8 = 35 - 67%, 9 = 67- 100%. Means within columns followed by different letters are significantly different according to Fisher’s LSD (P ≤ 0.10)

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16

ALABAMA AGRICULTURAL EXPERIMENT STATION

EVALUATION OF AVICTA® SEED TREATMENTS FOR RENIFORM NEMATODE MANAGEMENT IN SOYBEAN IN SOUTH ALABAMA, 2008
K. S. Lawrence, S. R. Moore, G. W. Lawrence, and J. R. Akridge

Experimental seed treatments were evaluated for the management of reniform nematodes in a naturally infested producer’s field near Huxford, Alabama. The field has a history of reniform nematode infestation, and the soil type is a Ruston very fine sandy loam (59 percent sand, 33 percent silt, 8 percent clay). The seed treatments were applied to the DP 7870 RR seed from Syngenta. Plots were four rows, 25 feet long, with 36- inch row spacing and were arranged in a randomized complete block design with six replications. All plots were maintained throughout the season with standard herbicide, insecticide, and fertility production practices as recommended by the Alabama Cooperative Extension System. Population densities of the reniform nematode were determined at 63 days after planting (DAP). Ten soil cores, 1 inch diameter and 6 inches deep, were collected from the two rows of each plot in a systematic sampling pattern. Nematodes were extracted using the gravity sieving and sucrose centrifugation technique. Plots were harvested on October 30. Data were statistically analyzed by PROC GLM and means compared using Fisher’s protected least significant difference test (P ≤ 0.10). Monthly average maximum temperatures from planting in May

through harvest in October were 87.4, 93.3, 92.8, 90.4, 88.0, and 83.9 degrees F with average minimum temperatures of 64.8, 69.6, 71.5, 71.4, 67.3, and 59.4 degrees F, respectively. Rainfall accumulation for each month was 2.8, 7.3, 5.0, 9.5, 1.7 inches with a total of 27.9 inches. The drought continued in 2008; thus, reniform nematode pressure was moderate and secondary to the lack of rainfall during bloom. Reniform nematode numbers at planting averaged 56 vermiform life stages per 150 cm3 of soil at planting. Plant stand was similar between all experimental seed treatments and the control (data not shown). Reniform numbers varied between the nematicide treatments; however, the control treatment of the fungicide with an insecticide—Apron Maxx RTA + Moly 0.166 + Cruiser (1)—supported lower populations. At mid-season on July 9, all seed treatments with Avicta supported fewer reniform (P ≤ 0.10) than the treatments with the experimental compounds A15945 and ASF271B. Soybean yields varied by 5.8 bushels per acre at harvest with an average of 44.2 bushels per acre produced over all nematicide treatments. The A15945 (3) treatment increased yields by 3.4 bushels per acre (P ≤ 0.10) as compared to the control.

EFFECT OF SEED TREATMENTS ON SOYBEAN YIELD AND NEMATODE NUMBERS
Treatment Apron Maxx RTA+Moly 0.166 ES Cruiser 5 FS Apron Maxx RTA+Moly 0.166 ES Cruiser 5 FS Avicta 4.17 FS Apron Maxx RTA+Moly 0.166 ES Cruiser 5 FS A15945 Apron Maxx RTA+Moly 0.166 ES Cruiser 5 FS ASF271B Apron Maxx RTA+Moly 0.166 ES Cruiser 5 FS Avicta 4.17 FS A15945 Apron Maxx RTA+Moly 0.166 ES Cruiser 5 FS Avicta 4.17 FS ASF271B Apron Maxx RTA+Moly 0.166 ES Cruiser 5 FS Avicta 4.17 FS A15945 ASF271B LSD (P ≤ 0.10) Rotylenchulus reniformis/ 150cm3 soil Rate 9 Jul 6.25 g ai/100 kg 923 c 50 g ai/100 kg 6.25 g ai/100 kg 1082 c 50 g ai/100 kg 0.15 g ai/100 kg 6.25 g ai/100 kg 3051 b 50 g ai/100 kg 0.6 g ai/100 kg 6.25 g ai/100 kg 3092 b 50 g ai/100 kg 20 g ai/100 kg 6.25 g ai/100 kg 5021 a 50 g ai/100 kg 0.15 g ai/100 kg 0.6 g ai/100 kg 6.25 g ai/100 kg 2408 bc 50 g ai/100 kg 0.15 g ai/100 kg 20 g ai/100 kg 6.25 g ai/100 kg 914 c 50 g ai/100 kg 0.15 g ai/100 kg 0.6 g ai/100 kg 20 g ai/100 kg 1243

1 2 3 4 5

Yield bu/A 30 Oct 43.9 bc

46.7 ab 47.3 a 43.2 c 43.8 b

6

41.5 c

7

42.9 c

2.3

Means followed by same letter do not differ significantly according to Fishers least significance test (P ≤ 0.10).

CONTRIBUTORS INDEX
Author J. R. Akridge W. C. Birdsong T. Dawkins D. P. Delaney B. Dillard J. Ducar B. Durbin D. H. Harkins J. Jones G. W. Lawrence K. S. Lawrence S. R. Moore B. E. Norris M. Pegues R. Petcher E. J. Sikora R. P. Yates Pages 16 6 8,12 5,6,7,8,9,10,11,12,13,14,15 6 8.,12 10 9,11 13,14,15 13,16 6,13,14,15,16 16 9,11 13,14,15 7 8,9,10,11,12,13,14,15 5