Soybean Disease and Nematode Ratings and Yields 2012 Variety and Fungicide Trial Summaries. Southern Stem Canker

Transcription

1 Soybean Disease and Nematode Ratings and Yields 2012 Variety and Fungicide Trial Summaries Variety reactions to: Frogeye Leaf Spot (FLS), Stem Canker, Sudden Death Syndrome (SDS), Cercospora Leaf Blight and Soybean Cyst Nematode (SCN) Fungicide Efficacy Against Strobilurin Resistant and Sensitive Frogeye Leaf Spot Heather M. Young Kelly, Assistant Professor Plant Pathologist University of Tennessee UT Extension & Research By Pat Donald, Adjunct Professor Nematologist USDA-ARS Entomology and Plant Pathology Department Jackson, TN Melvin A. Newman, Emeritus Professor Plant Pathologist University of Tennessee UT Extension Charcoal Rot Macrophomina phaseolina Southern Stem Canker Diaporthe phaseolorum var. meridionalis Frogeye Leaf Spot Cercospora sojina Funds Provided By: Tennessee Soybean Promotion Board Go to for more soybean data

2 Table of Contents 2012 Soybean Disease Loss Estimate... 3 Experimental Procedures... 4 Interpretation of Data... 5 Observations and Conclusions of Variety Trials... 6 Table 1 Summary of Variety Trials at Research and Education Center at Milan, TN... 8 Table 2 Summary of Variety Trials on-farm in Dyersburg, TN... 9 Table 4 Yields and Disease Ratings of Maturity Group III at Milan Table 3 Yields and Disease Ratings of Late Maturity Group IV Liberty Link at Milan Table 5 Yields and Disease Ratings of Early Maturity Group IV at Milan Table 6 Yields and Disease Ratings of Early Maturity Group IV at Dyersburg Table 7 Yields and Disease Ratings of Late Maturity Group IV at Milan Table 8 Yields and Disease Ratings of Late Maturity Group IV at Dyersburg Table 9 Yields and Disease Ratings of Early Maturity Group V at Milan Table 10 Yields and Disease Ratings of Early Maturity Group V at Dyersburg Observations and Conclusions of Fungicide Trials Table 11 Yields and Disease Ratings of Fungicides at Milan Table 12 Yields and Disease Ratings of Fungicides at Dyersburg Acknowledgements The cooperation and help of the following individuals is gratefully acknowledged for their assistance with these soybean trials: Dr. Blake Brown and his staff at the UT Research and Education Center at Milan and to Wesley Crowder (Senior Plot Foreman), Erin Ford and Daniel Wiggins (UT Technicians) for helping in the establishment, maintenance, and harvesting of research plots, and Marsha Camp for her secretarial skills in preparing this publication. Thank Dr. Pat Donald (ARS-USDA) for providing the nematode ratings. Also, thank Bob Williams (UT Grain Specialist) for obtaining the county variety seed source. Special thanks to Tim Campbell (UT County Director Dyer Co.) and soybean producer Byrl Fleming for providing land for plot work. Thanks to the Tennessee Soybean Promotion Board and its members for providing funds needed to carry out these trials. 2

3 Soybean Disease Loss Estimate for Tennessee 2012 %Loss 1 Anthracnose (Colletotrichum truncatum) Bacterial diseases (Pseudomonas syringae, P. syringae pv. tabaci, Xanthomonas campestris) 0 3 Brown leaf spot (Septoria glycines) Charcoal rot (Macrophomina phaseolina) Diaporthe/Phomopsis complex (Diaporthe & Phomopsis spp.) Downy mildew (Peronospora manshurica) 0 7 Frogeye leaf spot (Cercospora sojina) Fusarium wilt & root rot (Fusarium spp.) 0 9 Other a 0 10 Phytophthora root & stem rot (Phytophthora sojae) 0 11 Pod & stem blight (Diaporthe phaseolorum var. sojae) Purple stain (Cercospora kikuchii) Rhizoctonia aerial blight (Rhizoctonia solani) Sclerotinia stem rot (Sclerotinia sclerotiorum 0 15 Seeding disease (Rhizoctonia, Pythium & Fusarium spp.) Southern blight (Sclerotium rolfsi) 0 17 Soybean cyst nematode (Heterodera glycines) Root-knot (Meloidogyne spp.) Other nematodes b Stem canker (Diaporthe phaseolorum var. meridionalis) Sudden death syndrome (Fusarium solani Form A) Virus c 0 23 Brown stem rot (Phialophora gregata) 0 24 Soybean rust (Phakopsora pachyrhizi) 0 Total Per Cent Loss to Disease = 6,031,860 (bu. Loss) 13.74% loss *Total soybean production in TN for 2012: 43,900,000 (in bushels) *Total acres of soybeans harvested in 2012: 1,220,000 (acres) (As of Nov. 9, 2012) State Average for 2012: 36 (bushels/acre) a Identify diseases listed as other : b Identify nematodes listed as other : c Identify Virus diseases: How was this information obtained? Reniform and Lance Plot work and demonstration results and observations *These are estimates as of November 9, 2012 by the Tennessee Agricultural Statistics Service. 3

4 2012 Soybean Disease Report Heather M. Young Kelly, Assistant Professor & Melvin A. Newman, Emeritus Professor University of Tennessee Title: Evaluation of Soybean Cultivars and Foliar Fungicides for Control of Strobilurin Resistant Frogeye Leaf Spot Personnel: Heather M. Young Kelly, Assistant Professor Melvin A. Newman, Emeritus Professor Bob Williams, Extension Area Specialist III Tim Campbell, Dyer County Extension Director Blake Brown, Research Center Director Research & Education Center (REC) at Milan Objectives: Evaluate the effect of natural infections of Fusarium solani f.sp. glycines (Sudden Death Syndrome SDS), Diaporthe phaseolorum var. merdionalis (Southern Stem Canker), and Strobilurin resistant and sensitive Cercospora sojina (Frogeye Leaf Spot FLS) on available commercial soybean cultivars and the efficiency of commercial fungicides on managing soybean diseases. Procedures: Planting and Plot Information All plots were planted no-till, in a non-rotated soybean field with a four-row planter with cone seed-box attachments. Each plot was randomized and replicated - four replications at the REC at Milan location and three replications at the Dyersburg location. Research & Education Center (REC) at Milan Location On May 1, 2012 a total of 76 varieties (Liberty Link, MG III, IV Early, IV Late, and V Early) were planted in four-row plots with 30 row spacing and running 30 long at 8 seeds per ft. Irrigation was provided as needed with a center pivot system. For cultivar trials each 4-row plot was split and 2 rows were sprayed at R3 growth stage (beginning pod) on July 3, 2012 with Headline at 6 oz/a, tank mixed with Topguard at 6 oz/a plus 1% Induce as a spray adjuvant. For fungicide trials 2 of the 4 rows were treated at a specific growth stage (see Table 11). Yields were taken using 2 rows that were untreated (cultivar trial only) and 2 rows that were treated (cultivar and fungicide trials). Dyersburg Location On May 8, 2012 a total of 58 varieties (IV Early, IV Late, and V Early) were planted in four-row plots with 30 row spacing and running 33 long at 8 seeds per ft. Yields were taken from the middle 2 rows of the plots. Neither irrigation nor fungicides were applied to the cultivar trials. For fungicide trials the center 2 rows of each plot were treated at a specific growth stage (see Table 12) and were harvested. Disease Ratings The disease rating scale was 0 to 10 with 0 = no visible disease detected and 10 = extremely heavy disease. Dates of disease ratings for variety group and location are: Variety Groups Milan Location Dyersburg Location MG III 8/23/12 - MG IV Early 8/28/12 9/10/12 MG IV Late 9/4/12 9/10/12 MG IV Liberty Link 9/11/12 - MG V Early 9/11/12 9/19/12 4

5 Growing Season: The 2012 growing season was characterized by a warmer than usual spring followed by hot, dry drought conditions which persisted through most of the vegetative growth stages for soybeans. This was particularly true during the months of June and July when daily temperatures above 100 F were common. The early warm spring and associated early wheat harvest allowed planting ahead of the normal pace. Field conditions were predominately hotter and drier than normal with few fields receiving limited to moderate rainfall through July, which limited disease development. Widespread precipitation received in mid-july through August coupled with lower temperatures were beneficial to the state s soybean crop as well as developing low to moderate disease severity, which did not affect yield as severely as in a year with normal precipitation during vegetative growth stages. Impact: Each year soybean producers are provided an updated list of soybean varieties and fungicide trial results, including disease ratings of the most damaging diseases. This information has been a tremendous aid to producers in reducing disease and increasing yields by selecting disease resistant varieties, varieties that respond to a foliar fungicide, and using a fungicide that has the best efficacy to manage soybean diseases. Producers can obtain UT results either as a hard copy or online at Interpretation of Data: Tables on the following pages have been prepared with varieties listed in order of the overall average yield across replications, the highest-yielding variety being listed first. All yields presented have been adjusted to 13% moisture. At the bottom of the tables, LDS values stand for Least Significant Difference. The mean yields of any two varieties being compared must differ by at least the amount shown to be considered significantly different in yielding ability at the 5% level of probability of significance. For example, given that the LSD is 5.0 bu/a and the mean yield of Variety A was 43 bu/a and the mean yield of Variety B was 46 bu/a, then the two varieties are not statistically different in yield because the difference of 3 bu/a is less than the minimum of 5 bu/a required for them to be significant. Similarly, if the average yield of Variety C was 52 bu/a then it is significantly higher yielding than both Variety A (52 43 = 9 bu/a > LSD of 5) and Variety B (52 46 = 6 bu/a > LSD of 5). All disease ratings are based on a 0 to 10 scale, where 0 = no visible disease symptoms and 10 = most visible disease symptoms possible (without defoliation). On tables and in references in the observation and summary section low disease rating is defined from 0 to 3.3, moderate disease is from 3.4 to 6.3, and severe disease is from 6.4 to 10. Precautionary statement To protect people and the environment, pesticides should be used safely - this is everyone's responsibility, especially the applicators. Read and follow label directions carefully before you buy, mix, apply, store, or dispose of a pesticide. According to laws regulating pesticides, they must be used only as directed by the label. Disclaimer This publication contains pesticide recommendations that are subject to change at any time. The recommendations in this publication are provided only as a guide. It is always the pesticide applicator s responsibility, by law, to read and follow all current label directions for the specific pesticide being used. The label always takes precedence over the recommendations found in this publication. Use of trade or brand names in this publication is for clarity and information; it does not imply approval of the product to the exclusion of others that may be of similar, suitable composition, nor does it guarantee or warrant the standard of the product. The author(s), the University of Tennessee Institute of Agriculture and University of Tennessee Extension assume no liability resulting from the use of these recommendations. The University of Tennessee is an EEO/AA/Title VI/Title IX/Section 504/ADA/ADEA institution in the provision of its education and employment programs and services. All qualified applicants will receive equal consideration for employment without regard to race, color, national origin, religion, sex, pregnancy, marital status, sexual orientation, gender identity, age, physical or mental disability, or covered veteran status. Programs in agriculture and natural resources, 4-H youth development, family and consumer sciences and resource development. University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating. UT Extension provides equal opportunities in programs and employment. 5

6 Observations and Conclusions from the Evaluation of Soybean Cultivars (Tables 1 10) Maturity Group III at Milan: (Table 1 & 3) Yield The 7 MG III varieties, treated with fungicide, yield ranged from 26.4 to 42.0 bu/ac with 37.3 bu/ac average; yield from the same varieties that were untreated ranged from 26.1 to 40.9 bu/ac with 36.8 bu/ac average. Spraying fungicide increased yield of MG III varieties by an average of 0.5 bu/ac. FLS All varieties (treated and untreated) had low (0 to 3.3) ratings with 1 variety (Terral 38R10) with no visible symptoms (rated 0.0 when treated and untreated). Spraying fungicide decreased levels of FLS. Stem Canker The lowest yielding variety (AG 3932) in this grouping was the only variety with stem canker rated severe at 7.0 when treated and untreated. Late Maturity Group IV - Liberty Link Varieties at Milan: (Table 1 & 4) Yield The 10 Liberty Link varieties, treated with fungicide, yield ranged from 24.3 to 34.5 bu/ac with 29.6 bu/ac average; yield from the same varieties that were untreated ranged from 24.0 to 32.4 bu/ac with 27.7 bu/ac average. Spraying fungicide increased yield of MG III varieties by an average of 1.9 bu/ac. *Although only one replication was rated for diseases due to lodging and poor field conditions, all 4 replicates were used to calculate yield. FLS Only 1 variety of the 10 varieties had FLS symptoms (rated low: 1.0 when treated and 2.0 when untreated). Sudden Death Syndrome (SDS) All varieties had low to severe (2.0 to 7.0) levels of SDS but did not affect yield most likely due to dry, warm weather conditions and late symptom development. Early Maturity Group IV at Milan: (Table 1 & 5) Yield The 17 MG IV early varieties, treated with fungicide, yield ranged from 35.4 to 56.5 bu/ac with 45.3 bu/ac average; yield from the same varieties that were untreated ranged from 32.1 to 53.6 bu/ac with 43.3 bu/ac average. Spraying fungicide increased yield of MG III varieties by an average of 2.0 bu/ac. FLS 7 of the 17 varieties had no visible symptoms (rated 0.0 when treated and untreated), 1 variety rated low (1.0 when treated and 2.5 when untreated), 7 varieties rated low (0 to 2.8) when treated and rated moderate (3.5 to 5.5) when untreated, 2 varieties rated moderate (3.5 to 5.5) when treated and rated moderate (3.5) to severe (8.0) when untreated. Spraying fungicide decreased levels of FLS. Stem Canker Only 5 of the 17 varieties had symptoms ranging from low to moderate (3.0 to 5.5) when treated and moderate to severe (3.5 to 7.8) when untreated. Spraying fungicide decreased levels of stem canker. Sudden Death Syndrome (SDS) Only 5 of the 16 varieties had low levels of SDS symptoms which did not affect yield. Early Maturity Group IV at Dyersburg: (Table 2 & 6) Yield The 16 MG IV early varieties yield ranged from 53.6 to 35.0 bu/ac with 43.7 bu/ac average. FLS 4 of the 16 varieties had no visible symptoms (rated 0.0), 3 varieties rated low (0.3 to 0.7), and 9 varieties rated moderate (3.7 to 6.3). Late Maturity Group IV at Milan: (Table 1 & 7) Yield The 27 MG IV late varieties, treated with fungicide, yield ranged from 39.5 to 50.8 bu/ac with 44.5 bu/ac average; yield from the same varieties that were untreated ranged from 37.1 to 50.5 bu/ac with 44.8 bu/ac average. Spraying fungicide, on average, did not increase yields of the MG IV late varieties at the Milan location. FLS 10 of the 27 varieties had no visible symptoms (rated 0.0 when treated and untreated), 6 varieties had no visible symptoms when treated but rated low (0.3 to 3.3) when untreated, 1 variety rated low (0.8 when treated and 3.3 when untreated), 4 varieties rated low (1.0 to 1.5) when treated and moderate (3.8 to 5.0) when untreated, and 7 varieties rated low (0.8 to 3.0) when treated and severe (6.5 to 7.8) when untreated. Spraying fungicide decreased levels of FLS. Stem Canker Only 7 of the 28 varieties had symptoms: 2 of the 28 varieties had no visible symptoms when treated but rated low (0.3) when untreated, 1 variety rated low (2.0 when treated and 2.5 when untreated), 3 varieties rated low (2.0 to 3.3) when treated and moderate (4.0 to 4.5) when untreated, and 1 variety rated moderate (4.5) when treated and severe (7.8) when untreated. Spraying fungicide decreased levels of stem canker. Phytotoxicity All varieties had low to moderate (0.3 to 3.8) levels of phytotoxicity which may have contributed to some of the varieties yielding lower in treated plots verses untreated. 6

7 Late Maturity Group IV at Dyersburg: (Table 2 & 8) Yield The 27 MG IV late varieties yield ranged from 36.7 to 50.5 bu/ac with 43.1 bu/ac average. FLS 9 of the 27 varieties had no visible symptoms (rated 0.0), 9 other varieties rated low (0.3 to 3.0), 7 varieties rated moderate (4.3 to 6.0), and 2 varieties rated severe (7.0 to 7.3). Early Maturity Group V at Milan: (Table 1 & 9) Yield - The 15 MG V early varieties, treated with fungicide, yield ranged from 34.5 to 44.7 bu/ac with 40.4 bu/ac average; yield from the same varieties that were untreated ranged from 27.1 to 39.8 bu/ac with 34.2 bu/ac average. Spraying fungicide increased yield of MG III varieties by an average of 6.1 bu/ac. FLS 4 of the 15 varieties had no visible symptoms (rated 0.0 when treated and untreated), 3 varieties had no visible symptoms when treated but rated low (0.3 to 0.8) when untreated, 5 varieties rated low (0.3 to 0.8 when treated and 1.0 to 3.0 when untreated) and 3 varieties rated low (0.8 to 1.5) when treated and rated moderate (4.0 to 5.8) when untreated. Spraying fungicide decreased levels of FLS. Sudden Death Syndrome (SDS) 3 of the 15 varieties had no visible symptoms (rated 0.0 when treated and untreated), 11 varieties rated low (0.3 to 2.5 when treated and 0.3 to 2.5 when untreated) and 1 variety rated moderate (4.3 when treated and untreated). Spraying fungicide did not affect levels of SDS. Cercospora Blight 5 of the 15 varieties had no visible symptoms (rated 0.0 when treated and untreated), 8 varieties rated low (0.5 to 1.3 when treated and 1.0 to 3.3 when untreated), 1 variety rated low when treated (1.5) but rated moderated when untreated (4.3), and 1 variety rated moderate (3.8 when treated and 6.0 when untreated). Spraying fungicide decreased levels of Cercospora Blight. Phytotoxicity All but 5 varieties had low (0.3 to 1.3) levels of phytotoxicity, but did not affect yield. Early Maturity Group V at Dyersburg: (Table 2 & 10) Yield The 15 MG V earlier varieties yield ranged from 40.8 to 58.6 bu/ac with 50.4 bu/ac average. FLS 2 of the 15 varieties had no visible symptoms (rated 0.0), 6 varieties rated low (0.3 to 3.0), 5 varieties rated moderate (3.7 to 5.0), and 2 varieties rated severe (7.0 to 7.3). Sudden Death Syndrome (SDS) Only 2 varieties had SDS symptoms rated low (0.3 and 1.0). Cercospora Blight Only 1 variety had no visible symptoms, 9 varieties rated low (1.0 to 3.3), and 5 varieties rated moderate (3.7 to 5.7). Cultivar Conclusions: MG III The MG III yields did not benefit as much as the later maturity groups from the late season precipitation. The low FLS severity is also due to the overall drier season, but the late season precipitation did provide the moisture needed for disease development. FLS contributed to the reduction in MG III yields, treated and untreated, with fungicide application reducing FLS severity across all varieties and increasing yields in 4 of the 7 varieties. Stem canker severely reduced yields on variety AG 3932, with fungicide application not reducing severity. Overall, conditions were not favorable for moderate to severe disease development on MG III varieties and fungicide application did not significantly increase yields on the varieties tested. Early MG IV Late season precipitation favored soybean production as well as FLS disease in the early MG IV varieties. FLS only reached low to moderate levels of severity due to the dry and hot conditions delaying FLS development in the majority of the varieties. The combination of FLS and stem canker contributed to yield loss across early MG IV varieties at the Milan location, especially in varieties Armor 44-R08 RR2Y and Steyer 4203 R2. Fungicide application reduced FLS severity across all varieties and reduced stem canker severity which contributed to higher yields. Late MG IV Similar to the early MG IV varieties the late MG IV varieties benefited from the late season precipitation and were not severely affected by disease. FLS was able to develop to severe levels on some untreated varieties but developed late enough in the season that it did not significantly affect yields. Late MG IV Liberty Link The 10 late MG IV Liberty Link varieties evaluated at Milan were planted into poor soil and only the first 2 blocks received irrigation, which most likely contributed to the low yields as did sudden death syndrome (SDS). The varieties evaluated have the potential to be high yielding varieties but only in a field with no history of SDS. Early MG V The early MG V varieties evaluated yielded well with and without irrigation and in the presence of multiple diseases. Fungicide application had the greatest increase in yields across the early MG V varieties evaluated due to reducing disease severity, which is expected on later maturity varieties. 7

8 Table 1. Average frogeye leaf spot (FLS) and other disease ratings and soybean variety yields evaluated at the Research and Education Center at Milan, Tennessee during 2012 with irrigation. Frogeye Leaf Spot Rating MG III Early MG IV Late MG IV MG IV Liberty Link Early MG V Treated Untreated Treated Untreated Treated Untreated Treated Untreated Treated Untreated None (0) Low (1-3) Moderate (4-6) Severe (7-10) Avg. FLS Avg. Yield (Increase) bu/ac 37.3 (0.5) (2.0) (-0.3) (1.9) (6.1) Highest Yielding Variety DG 32RY39 DG 32RY39 AG 4232 AG 4232 Armor 47- R17 RR DL 4633 DSR Go-Soy 4910LL Go-Soy 4910LL AG 5332 Croplan 5081 Yield (bu/ac) Frogeye Leaf Spot Rating(1-10) Stem Canker Rating (1-10) Cercospora Blight (1-10) Lowest Yielding Variety AG 3932 AG 3932 Steyer 4203R2 Steyer 4203R2 Progeny 4710RY Schillinger 478RCS Ag Venture 43A4 Ag Venture 43A4 Hornbeck RY5221 AG 5532 Yield (bu/ac) Frogeye Leaf Spot Rating(1-10) Stem Canker Rating (1-10) Cercospora Blight (1-10) Plots were planted on 5/1/12, no-till, in a non-rotated soybean field and irrigated as needed by a pivot system. Treated plots were sprayed at R3 growth stage with 6 oz/a, tank mixed with 6 oz/a plus 1% Induce as a spray adjuvant. Yields were adjusted to 13% moisture. Disease ratings were taken in late August and early September using a scale of 0 to10, where 0 = no disease and 10 = most disease possible. All data was analyzed using the ARM 7 program. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 8

9 Table 2. Average frogeye leaf spot (FLS) ratings and soybean variety yields evaluated on-farm in Dyersburg, TN during 2012 without irrigation. Frogeye Leaf Spot Rating Early MG IV Late MG IV Early MG V None (0) Low (1-3) Moderate (4-6) Severe (7-10) Avg. FLS Avg. Yield (bu/ac) Highest Yielding Variety AG 4232 Hornbeck R4924 Progeny 5111RY Yield (bu/ac) Frogeye Leaf Spot Rating(1-10) Lowest Yielding Variety DL 4300RR Hornbeck RY4721 Schillinger 5220 Yield (bu/ac) Frogeye Leaf Spot Rating(1-10) Plots were planted on 5/8/12, no-till, in a non-rotated soybean field with no irrigation. Yields were adjusted to 13% moisture. Disease ratings were taken in late August and early September using a scale of 0 to10, where 0 = no disease and 10 = most disease possible. All data was analyzed using the ARM 7 program. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 9

10 Table 3. Yields and disease ratings of seven Maturity Group III Roundup Ready soybean varieties evaluated at the Research and Education Center at Milan, Tennessee during Data (unit or scale) Yield (bu/ac) Yield (bu/ac) Yield Difference Frogeye Leaf Spot (1-10) Frogeye Leaf Spot (1-10) Stem Canker (1-10) Stem Canker (1-10) Soybean Cyst Nematode (Greenhouse Ratings) Variety Treated Untreated (bu/ac) Treated Untreated Treated Untreated Race 2 Race 3 Race 5 DG 32RY39 RR2Y/STS HS S HS Armor 39-R16 RR2/STS HS MR HS NK S39-U2 RR2Y HS MS HS Terral REV-38R HS MS HS AG 3731 GENRR2Y HS MR HS DL 3980 R2Y HS MS HS AG 3932 GENRR2Y HS MS HS LSD (P=.05) Average Plots were planted on 5/1/12, no-till, in a non-rotated soybean field and irrigated as needed by a pivot system. Treated plots were sprayed at R3 growth stage on 7/3/12 with 6 oz/a, tank mixed with 6 oz/a plus 1% Induce as a spray adjuvant. Yields were harvested 9/20/12 and adjusted to 13% moisture. Disease ratings were taken 8/23/12 using a scale of 0 to10, where 0 = no disease and 10 = most disease possible. Soybean Cyst Nematode ratings compiled by Dr. Pat Donald, Research Plant Pathologist. Results from soybeans planted in greenhouse where each pot was inoculated with 2500 eggs/120 cm3 of soil and each rating is an average of 4-7 replications (pots). HS = highly susceptible, S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant. Race 2 (HG Type ), Race 3 (HG Type 7), Race 5 (HG Type 2.5.7) HG Type explanation: numbers correspond to greater than 10% reproduction on sources of soybean resistance when compared to a standard susceptible soybean, i.e, 1= PI , 2= PI 88788, 5 = , 7= PI All data was analyzed using the ARM 7 program. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 10

11 Table 4. Yields and disease ratings of 10 Late Maturity Group IV Liberty Link soybean varieties evaluated at the Research and Education Center at Milan, Tennessee during Data (unit or scale) Yield (bu/ac) Yield Difference Frogeye Leaf Spot (0-10) Stem Canker (0-10) Sudden Death Syndrome (0-10) Soybean Cyst Nematode (Greenhouse Ratings) Variety Treated Untreated (bu/ac) Treated Untreated Treated Untreated Treated Untreated Race 2 Race 3 Race 5 Go-Soy S HS HS Halo 4: MS MS S USG 74G S HS S DL Micah S MS HS DL Micah S HS HS Go-Soy S HS HS Progeny HS HS S DL Micah S HS HS Halo 4: S HS S Ag Venture 43A HS MS S LSD (P=.05) Average Plots were planted on 5/1/12 no-till, in a non-rotated soybean field and irrigated as needed by pivot system. Treated plots were sprayed at R3 growth stage on 7/24/12 with 6 oz/a, tank mixed with 6 oz/a plus 1% Induce as a spray adjuvant. Yields were harvested 10/17/12 and adjusted to 13% moisture. Disease ratings were taken 9/11/12 using a scale of 0-10, where 0 = no disease and 10 = most disease possible. Soybean Cyst Nematode ratings compiled by Dr. Pat Donald, Research Plant Pathologist. Results from soybeans planted in greenhouse where each pot was inoculated with 2500 eggs/120 cm3 of soil and each rating is an average of 4-7 replications (pots). HS = highly susceptible, S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant. Race 2 (HG Type ), Race 3 (HG Type 7), Race 5 (HG Type 2.5.7) HG Type explanation: numbers correspond to greater than 10% reproduction on sources of soybean resistance when compared to a standard susceptible soybean, i.e, 1= PI , 2= PI 88788, 5 = , 7= PI Only one rep was rated for disease due to lodging and poor field conditions. All data was analyzed using the ARM 7 program. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 11

12 Table 5. Yields and disease ratings of 17 Early Maturity Group IV Roundup Ready soybean varieties evaluated at the Research and Education Center at Milan, Tennessee during Data (unit or scale) Yield (bu/a) Yield Difference Frogeye Leaf Spot (1-10) Stem Canker (1-10) Sudden Death Syndrome (1-10) Soybean Cyst Nematode (Greenhouse Ratings) Variety Treated Untreated (bu/a) Treated Untreated Treated Untreated Treated Untreated Race 2 Race 3 Race 5 AG 4232 GENRR2Y/STS S MR HS Armor 46-R HS MS HS Mycogen 5N451 RR2Y HS HS HS LG C4411 R S MR HS Croplan 4541 GENRR2Y HS MS HS Ag Venture 43A2 RR2Y/STS HS MR HS Armor 46-R42 RR2Y HS MS HS Terral REV-44R HS MS HS DL 4343 R2Y HS S HS Armor 44-R08 RR2Y HS MR HS Progeny 4510 RY/STS HS HS HS DG 31RY45 RR2Y HS HS HS Croplan 4391 GENRR2Y HS MS HS NK S41-J6 RR2Y S MS HS DL 4300 RR HS HS HS Steyer 4203 R MS S HS DG 39RY43 RR2Y NA NA NA S MS HS LSD (P=.05) Average Plots were planted on 5/1/12, no-till, in a non-rotated soybean field and irrigated as needed by a pivot system. Treated plots were sprayed at R3 growth stage on 7/3/12 with 6 oz/a, tank mixed with 6 oz/a plus 1% Induce as a spray adjuvant. Yields were harvested 9/24/12 and adjusted to 13% moisture. Disease ratings were taken 8/28/12 using a scale of 0 to 10, where 0 = no disease and 10 = most disease possible. Soybean Cyst Nematode ratings compiled by Dr. Pat Donald, Research Plant Pathologist. Results from soybeans planted in greenhouse where each pot was inoculated with 2500 eggs/120 cm3 of soil and each rating is an average of 4-7 replications (pots). HS = highly susceptible, S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant. Race 2 (HG Type ), Race 3 (HG Type 7), Race 5 (HG Type 2.5.7) HG Type explanation: numbers correspond to greater than 10% reproduction on sources of soybean resistance when compared to a standard susceptible soybean, i.e, 1= PI , 2= PI 88788, 5 = , 7= PI Phytotoxicity was observed on Croplan 4541 and rated 0.3 out of 10. Phytotoxicity is an interveinal chlorsis reaction (yellowing of leaves) to the application. Ratings were taken 8/28/12 using a scale of 0 to 10 where 0 = no symptoms and 10 = 100% yellowed. All data was analyzed using the ARM 7 program. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 12

13 Table 6. Yields and frogeye leaf spot disease ratings of 16 Early Maturity Group IV Roundup Ready soybean varieties evaluated on-farm in Dyersburg, TN during Yield (bu/ac) a Frogeye Leaf Spot (0-10) b Soybean Cyst Nematode (Greenhouse Ratings) Race 2 Race 3 Race 5 Variety AG 4232 GENRR2Y/STS S MR HS Armor 44-R08 RR2Y HS MR HS Terral REV-44R HS MS HS Armor 46-R42 RR2Y HS MS HS Mycogen 5N451 RR2Y HS HS HS Steyer 4203 R MS S HS Armor 46-R HS MS HS NK S41-J6 RR2Y S MS HS Ag Venture 43A2 RR2Y/STS HS MR HS LG C4411 R S MR HS Croplan 4391 GENRR2Y HS MS HS Progeny 4510 RY/STS HS HS HS DL 4343 R2Y HS S HS Croplan 4541 GENRR2Y HS MS HS DG 39RY43 RR2Y S MS HS DL 4300 RR HS HS HS LSD (P=.05) Average Plots were planted on 5/8/12, no-till, in a non-rotated soybean field with no irrigation. a Yields were harvested 10/4/12 and adjusted to 13% moisture. b Disease ratings taken on 8/28/12 using a scale of 0-10, where 0 = no disease and 10 = most disease possible. Soybean Cyst Nematode ratings compiled by Dr. Pat Donald, Research Plant Pathologist. Results from soybeans planted in greenhouse where each pot was inoculated with 2500 eggs/120 cm3 of soil and each rating is an average of 4-7 replications (pots). HS = highly susceptible, S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant. Race 2 (HG Type ), Race 3 (HG Type 7), Race 5 (HG Type 2.5.7) HG Type explanation: numbers correspond to greater than 10% reproduction on sources of soybean resistance when compared to a standard susceptible soybean, i.e, 1= PI , 2= PI 88788, 5 = , 7= PI Most of the growing season was hot and dry and disease pressure was only moderate but enough to rate differences among the varieties. No fungicide application was made on any variety. All data was analyzed using ARM 7. Data Provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 13

14 Table 7. Yields and disease ratings of 27 Late Maturity Group IV Roundup Ready soybean varieties evaluated at the Research and Education Center in Milan, Tennessee during Data (unit or scale) Yield Yield Frogeye Leaf Stem Canker Phytotoxicity Soybean Cyst Nematode (bu/ac) Difference Spot (0-10) (0-10) (0-10) (Greenhouse Ratings) Variety Treated Untreated bu/ac Treated Untreated Treated Untreated Treated Race 2 Race 3 Race 5 Armor 47-R17 RR2Y/STS S MS HS LG C4885 R HS MS HS DL 4633 R2Y S HS HS Steyer 4701 R MS MS HS Mycogen 5N478 RR2Y HS MR HS Hornbeck HBK RY HS S HS Hornbeck HBK R HS MS HS MorSoy RT46X71 RR2Y HS MS HS AG 4832 GENRR2Y/STS HS MR HS NK S46-A1 RR2Y HS MR HS DG 33RY47 RR2Y/STS HS S HS Armor 48-R91 RR HS MR HS AG 4632 GENRR2Y/STS HS HS HS NK S49-F8 RR* HS MR HS Ag Venture 47K S S HS Schillinger 4990RC S MR HS Croplan 4801S GENRR2Y/STS S MS HS USG 74B81 R2Y HS MR HS DL 4810 RR HS S HS Terral REV-49R S MR HS Ag Venture 48K S MS HS Terral REV-48R HS MS HS MorSoy RT46X29 RR2Y/STS HS S HS USG 74A79 R2Y/STS HS HS HS Schillinger 478RCS HS MR HS Croplan 4799S GENRR2Y/STS HS HS HS Progeny 4710 RY/STS HS HS HS LSD (P=.05) Average Plots were planted on 5/1/12, no-till, in a non-rotated soybean field and irrigated as needed by a pivot system. Treated plots were sprayed at R3 growth stage on 7/17/12 with 6 oz/a, tank mixed with 6 oz/a plus 1% Induce as a spray adjuvant. Yields were harvested 9/24/12 and adjusted to 13% moisture. Disease ratings were taken 9/4/12 using a scale of 0-10, where 0 = no disease and 10 = most disease possible. Phytotoxicity is an interveinal chlorsis reaction (yellowing of leaves) to the application. Ratings were taken 9/4/12 using a scale of 0 to 10 where 0 = no symptoms and 10 = 100% yellowed. Soybean Cyst Nematode ratings compiled by Dr. Pat Donald, Research Plant Pathologist. Results from soybeans planted in greenhouse where each pot was inoculated with 2500 eggs/120 cm3 of soil and each rating is an average of 4-7 replications (pots). HS = highly susceptible, S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant. Race 2 (HG Type ), Race 3 (HG Type 7), Race 5 (HG Type 2.5.7) HG Type explanation: numbers correspond to greater than 10% reproduction on sources of soybean resistance when compared to a standard susceptible soybean, i.e, 1= PI , 2= PI 88788, 5 = , 7= PI *Sudden Death Syndrome (SDS) symptoms were only observed on variety NK S49-F8 RR at 1.3 in Treated plots and 1.0 in Untreated plots All data was analyzed using the ARM 7 program. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 14

15 Table 8. Yields and frogeye leaf spot (FLS) ratings of 27 Late Maturity Group IV Roundup Ready soybean varieties evaluated on-farm in Dyersburg, Tennessee during Soybean Cyst Nematode Data (unit or scale) Yield Frogeye Leaf (bu/ac) a Spot (0-10) b (Greenhouse Ratings) Variety Race 2 Race 3 Race 5 Hornbeck HBK R HS MS HS AG 4832 GENRR2Y/STS HS MR HS Steyer 4701 R MS MS HS DL 4810 RR HS S HS NK S49-F8 RR HS MR HS Schillinger 4990RC S MR HS USG 74A79 R2Y/STS HS HS HS Terral REV-49R S MR HS AG 4632 GENRR2Y/STS HS HS HS NK S46-A1 RR2Y HS MR HS Croplan 4799S GENRR2Y/STS HS HS HS MorSoy RT46X29 RR2Y/STS HS S HS Ag Venture 48K S MS HS Terral REV-48R HS MS HS DG 33RY47 RR2Y/STS HS S HS Progeny 4710 RY/STS HS HS HS Armor 47-R17 RR2Y/STS S MS HS Ag Venture 47K S S HS Armor 48-R91 RR HS MR HS Croplan 4801S GENRR2Y/STS S MS HS Schillinger 478RCS HS MR HS DL 4633 R2Y S HS HS USG 74B81 R2Y HS MR HS LG C4885 R HS MS HS MorSoy RT46X71 RR2Y HS MS HS Mycogen 5N478 RR2Y HS MR HS Hornbeck HBK RY HS S HS LSD (P=.05) Average Plots were planted on 5/8/12, no-till, in a non-rotated soybean field with no irrigation. a Yields were harvested 10/4/12 and adjusted to 13% moisture. b Disease ratings taken 9/10/12 using a scale of 0-10, were 0 = no disease and 10 = most disease possible. Soybean Cyst Nematode ratings compiled by Dr. Pat Donald, Research Plant Pathologist. Results from soybeans planted in greenhouse where each pot was inoculated with 2500 eggs/120 cm3 of soil and each rating is an average of 4-7 replications (pots). HS = highly susceptible, S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant. Race 2 (HG Type ), Race 3 (HG Type 7), Race 5 (HG Type 2.5.7) HG Type explanation: numbers correspond to greater than 10% reproduction on sources of soybean resistance when compared to a standard susceptible soybean, i.e, 1= PI , 2= PI 88788, 5 = , 7= PI Most of the growing season was hot and dry and disease pressure was only moderate but enough to rate differences among the varieties. No fungicide application was made on any variety. All data was analyzed using ARM 7. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 15

16 Table 9. Yields and disease ratings of 15 Early Maturity Group V Roundup Ready soybean varieties evaluated at the Research and Education Center in Milan, Tennessee during Data (unit or scale) Yield Frogeye Leaf Sudden Death Cercospora Blight Phytotoxicity Soybean Cyst Nematode Yield (bu/ac) Difference Spot (0-10) Syndrome (0-10) (0-10) (0-10) (Greenhouse Ratings) Variety Treated Untreated bu/ac Treated Untreated Treated Untreated Treated Untreated Treated Race 2 Race 3 Race 5 AG 5332 GENRR2Y HS MS HS Terral REV-51R HS S HS NK S51-H9 RR2Y HS MS HS Armor 53-R15 RR HS MR HS Progeny 5111 RR2Y HS MS HS MorSoy 54X41 RR2Y S HS HS AG 5532 GENRR2Y S MS HS MorSoy RT5429 RR HS S HS USG 75J50 R2Y S HS S Croplan 5081 GENRR2Y S MR HS USG 75B21 R2Y S S HS AG 5632 GENRR2Y/STS* S S HS Armor X1313 RR S MS HS Schillinger 5220 RC HS HS HS Hornbeck HBK RY HS HS HS LSD (P=.05) Average Plots were planted on 5/1/12, no-till, in a non-rotated soybean field and irrigated as needed by a pivot system. Treated plots were sprayed at R3 growth stage on 7/24/12 with 6 oz/a, tank mixed with 6 oz/a plus 1% Induce as a spray adjuvant. Yields were harvested 10/29/12 and adjusted to 13% moisture. Disease ratings were taken 9/11/12 using a scale of 0-10, where 0 = no disease and 10 = most disease possible. Phytotoxicity is an interveinal chlorsis reaction (yellowing of leaves) to the application. Ratings were taken 9/11/12 using a scale of 0 to 10 where 0 = no symptoms and 10 = 100% yellowed. Soybean Cyst Nematode ratings compiled by Dr. Pat Donald, Research Plant Pathologist. Results from soybeans planted in greenhouse where each pot was inoculated with 2500 eggs/120 cm3 of soil and each rating is an average of 4-7 replications (pots). HS = highly susceptible, S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant. Race 2 (HG Type ), Race 3 (HG Type 7), Race 5 (HG Type 2.5.7) HG Type explanation: numbers correspond to greater than 10% reproduction on sources of soybean resistance when compared to a standard susceptible soybean, i.e, 1= PI , 2= PI 88788, 5 = , 7= PI *Stem Canker symptoms were only observed on variety AG 5632 at 0.5 in Treated and Untreated plots. All data was analyzed using the ARM 7 program. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 16

17 Table 10. Yields and disease ratings of 15 Early Maturity Group V Roundup Ready soybean varieties evaluated on-farm in Dyersburg, Tennessee during Soybean Cyst Nematode Yield Frogeye Leaf Sudden Death Cercospora (Greenhouse Ratings) (bu/ac) Spot (0-10) Syndrome (0-10) Blight (0-10) Variety Race 2 Race 3 Race 5 Progeny 5111 RR2Y HS MS HS USG 75B21 R2Y S S HS Croplan 5081 GENRR2Y S MR HS NK S51-H9 RR2Y HS MS HS MorSoy RT5429 RR HS S HS Armor X1313 RR S MS HS Terral REV-51R HS S HS Hornbeck HBK RY HS HS HS AG 5332 GENRR2Y HS MS HS Armor 53-R15 RR HS MR HS USG 75J50 R2Y S HS S AG 5532 GENRR2Y S MS HS MorSoy 54X41 RR2Y S HS HS AG 5632 GENRR2Y/STS S S HS Schillinger 5220 RC HS HS HS LSD (P=.05) Average Plots were planted on 5/8/12, no-till, in a non-rotated soybean field with no irrigation. Yields were harvested 10/24/12 and adjusted to 13% moisture. Disease ratings taken 9/19/12 using a scale of 0-10, where 0 = no disease and 10 = most disease possible. Soybean Cyst Nematode ratings compiled by Dr. Pat Donald, Research Plant Pathologist. Results from soybeans planted in greenhouse where each pot was inoculated with 2500 eggs/120 cm3 of soil and each rating is an average of 4-7 replications (pots). HS = highly susceptible, S = susceptible, MS = moderately susceptible, MR = moderately resistant, R = resistant. Race 2 (HG Type ), Race 3 (HG Type 7), Race 5 (HG Type 2.5.7) HG Type explanation: numbers correspond to greater than 10% reproduction on sources of soybean resistance when compared to a standard susceptible soybean, i.e, 1= PI , 2= PI 88788, 5 = , 7= PI Most of the growing season was hot and dry and disease pressure was only moderate but enough to rate differences among the varieties. No fungicide application was made on any variety. All data was analyzed using ARM 7. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 17

18 18

19 Observations and Conclusions from the Evaluation of Foliar Fungicides (Tables 11-12) Despite the hot and dry growing season frogeye leaf spot (FLS) was able to develop to severe levels on the highly susceptible cultivar Asgrow 4703 to evaluated different classes of fungicides and different application timings. Both locations, REC at Milan and on-farm in Dyersburg, have had strobilurin resistant FLS identified in 2011 and 2012, but both strobilurin- sensitive and resistant populations are present in the fields. As expected, fungicides containing only a strobilurin (FRAC Code 11 Aproach, Evito, and Headline) were not effective in controlling FLS, but fungicides with different chemistries (different FRAC Codes) did reduce FLS severity. Fungicides tested with different chemistries and mixtures included triazoles (FRAC Code 3 Topguard and Proline, only contain a triazole; Quadris TOP, Stratego YLD, and Quilt Xcel, are mixtures of triazoles and strobilurins), succinate dehydrogenase inhibitors (SDHIs FRAC Code 7 Priaxor is a mixture of an SDHI and strobilurin), and methyl benzimidazole carbamates (MBC FRAC Code 1 Topsin-M). At both locations 2 applications of Topguard (triazole FRAC Code 3) at reproductive growth stage R3 (beginning pod) and R5 (beginning seed) resulted in the lowest FLS severity and the highest yield. Although, it is not recommended to spray two consecutive applications of a fungicide in the same FRAC Code as this is increasing the selection pressure for resistant pathogens. Furthermore, yields were not significantly different between the top 4 treatments at each location which included mixtures of strobilurins and other chemistries (triazoles and SDHIs) as well as Topsin-M (MBC FRAC Code 1) applied once at growth stage R3 or 2 applications one at growth stage R1 (beginning bloom) and the second at R3 (beginning pod). Best application timing evaluated in 2012 was at reproductive stage R3 (Beginning pod) and a second application at R5 (beginning seed). The 2 applications of Topguard may have yielded the best due to a second application at R5 (beginning seed) that added continued protection late into the season. Many of the other non-strobilurin fungicides may have yielded better if a second application at R5 was sprayed. Going into the 2013 season please be aware of the possibility of fungicide resistance in pathogen populations, especially Cercospora sojina the causal agent of FLS. Best management practices to avoid development of fungicide resistant pathogens include: Using management strategies other than fungicides such as resistant varieties and cultural practices (i.e. crop rotation, tillage) to manage disease levels Using multiple fungicide chemistries/frac Codes to control disease, fungicides with different FRAC Codes can be mixed to reduce selection pressure for specific fungicide resistance in pathogen populations Using fungicides only when warranted to control disease every time a fungicide is applied a selection pressure is placed on the pathogen population and individual isolates may be selected that are resistant to the fungicide, minimizing such selection pressure is vital in prolonging the efficacy and longevity of a fungicide 19

20 Table 11. Yields and disease ratings of 11 fungicide treatments evaluated at the Research and Education Center at Milan, TN during Application Yield Frogeye Leaf Defoliation Fungicide a FRAC Code b Rate Unit Growth Stage c (bu/ac) d Spot (0-10) e (0-100%) f Topguard fl oz/a R3 Topguard fl oz/a R Priaxor fl oz/a R Headline fl oz/a R Stratego YLD fl oz/a R Proline fl oz/a R1 Stratego YLD fl oz/a R Aproach fl oz/a R Quilt Xcel fl oz/a R Topsin-M lb/a R Topguard fl oz/a R Quadris TOP fl oz/a R Evito fl oz/a R Domark fl oz/a R Untreated Check LSD (P=.05) Average Plots were planted with Asgrow 4703 on 5/1/12, no-till, in a non-rotated soybean field, irrigated as needed by pivot system. a All treatments received 1% tank mix of Induce as a spray adjuvant. b Fungicide Resistance Action Committee (FRAC) Code is a system of numbers and letters that organizes fungicide groups according to their cross resistance behavior. Fungi resistant to one fungicide in a FRAC Code group will be resistant to all fungicides in that Code group. Strobilurin fungicides are FRAC Code 11 and Triazole fungicides are FRAC Code 3. c Treatments applied at growth stage R1 were sprayed 6/18/12, at R3 were sprayed 7/3/12, and at R5 were sprayed on 7/24/12. d Yields were harvested on 10/24/12 and adjusted to 13% moisture. e Disease ratings were taken 8/2/12 using a scale of 0 to 10, where 0 = no disease and 10 = the most disease possible. f Defoliation ratings were taken 9/14/12. Phytotoxicity observed in plots with two applications of Topguard at R3 and R5, rated 3 out of 10. Phytotoxicity is an interveinal chlorsis reaction (yellowing of leaves) to the application. Ratings were taken 8/2/12 using a scale of 0 to 10 where 0 = no symptoms and 10 = 100% yellowed. Hot and dry growing season reduced severity of diseases even with pivot irrigation. Strobilurin resistant FLS has been identified in this field in 2011 and The ARM 7 program was used for data analysis. Data provided by Heather Young Kelly and Melvin Newman, Plant Pathologists, University of Tennessee. 20