The study was designed to optimize insecticide and fungicide usage on soybean by comparing different products applied at different timings. To explain yield responses, foliar disease severity and aphid populations were assessed throughout the season

Bestor, Nathan

Mueller, Daren

O'Neal, Matthew

Pedersen, Palle

Ritson, Rebecca

Robertson, Alison

English

The study was designed to optimize insecticide and fungicide usage on soybean by comparing different products applied at different timings. To explain yield responses, foliar disease severity and aphid populations were assessed throughout the season.</p

Digital Repository @ Iowa State University (ISU)

Iowa State University, Northeast Research and Demonstration Farm ISRF09-13  47 Fungicide-Insecticide Study on Soybeans  RFR-A9114  Nathan Bestor, research associate Rebecca Ritson, graduate assistant Daren Mueller, extension specialist Alison Robertson, assistant professor Matt O’Neal, assistant professor Department of Agronomy  Introduction The study was designed to optimize insecticide and fungicide usage on soybean by comparing different products applied at different timings. To explain yield responses, foliar disease severity and aphid populations were assessed throughout the season.  Materials and Methods Plot size was six 30-in. rows by 43 ft long. The field was arranged in a randomized block design with 6 replications. The two middle rows were harvested.  Fungicides and insecticides were sprayed either alone or in combination at growth stage R1 or growth stage R3. Two controls were included, one was a non-treated control and the other was an IPM-based control that used the 250-aphid threshold to trigger an insecticide application (Table 1). The R1 sprays were on July 16, 2009 and the R3 sprays were on July 29, 2009.  Data was collected for foliar disease three times during the summer. The upper and lower canopies were assessed for percent coverage of foliar disease caused by fungal pathogens. Because of low disease pressure, only the last assessment (~ R5.5) was included in Table 1. Aphids were assessed on selected treatments regularly throughout the summer and are reported as Cumulative Aphid Days (CAD). Before harvest, stems from selected treatments were rated for anthracnose stem blight. Finally, grain yield (adjusted to 13% moisture) and moisture were recorded.   Aphid populations at Nashua did reach threshold and IPM plots were sprayed August 22, 2009.   Results and Discussion Yields were not different in the fungicide treatments when compared with the control  (P > 0.1) (Table 1). This is likely due to foliar disease levels not being very high during the 2009 growing season.   Aphid pressure was high for the second year in a row at Northeast Research Farm. All insecticide treatments, including tank mixes, were effective in reducing aphid populations and in increasing yield when compared with the control. However, there were no differences when those treatments were compared with the IPM control (Table 1).  The application timings at R1 and R3 of the treatments were not much different from each other this past growing season. We suspect this has to do with the R1 and R3 growth stages being very close together in 2009.  This project is a three-year study and data from 2009 represents the second year of the study. Data from 2008 and 2010 will be used to continue to look for interactions between insecticides and fungicides and the yield and disease responses at application timings at R1 and R3.  Acknowledgements Thanks to Ken Pecinovsky, Northeast Research Farm superintendent, for his assistance and cooperation in this study. This work was funded, in part, by soybean checkoff funds from the Iowa Soybean Association.  Iowa State University, Northeast Research and Demonstration Farm ISRF09-13  48      Table 1. Fungicides and insecticides applied to soybeans at growth stages R1 and R3 and resultant disease and insect pressure and yield response.  Treatment Rate (oz/ac) Timing Class Brown spot (%) CAD* Moisture (%) Yield (bu/ac) Stratego Pro 4 R1  Fung 0.78 20754 13.10 62.56 Stratego Pro 4 R3 Fung 1.60 17981 13.44 61.90 Domark 4 R1  Fung 2.77 24667 13.58 59.34 Domark 4 R3 Fung 3.70 25292 13.06 56.95 Picoxystrobin 6 R1  Fung 2.57 19283 13.68 57.67 Picoxystrobin 6 R3 Fung 5.10 5428 13.32 60.30 LEM-17 16 R1  Fung 1.78 23606 13.24 59.87 LEM-17 16 R3 Fung 4.30 19527 13.19 60.00 Headline 6 R1  Fung 1.82 22915 13.15 61.82 Headline 6 R3 Fung 2.43 22272 13.37 62.31 Leverage 3.76 R1  Ins 4.05 8494 13.44 66.87 Leverage 3.76 R3 Ins 4.87 4408 13.43 58.64 Belay 3 R1  Ins 3.47 42730 13.14 61.21 Belay 3 R3 Ins 5.05 20613 13.06 59.25 Asana 9.6 R1  Ins 4.48 20762 13.37 55.40 Asana 9.6 R3 Ins 4.88 20312 13.34 62.00 Stratego Pro + Leverage 4/3.6 R1  Mix 0.82 10682 13.16 60.20 Stratego Pro + Leverage 4/3.6 R3 Mix 2.20 3980 13.20 65.43 Domark + Belay 4, 3 R1  Mix 2.82 26724 13.29 54.02 Domark + Belay 4, 3 R3 Mix 3.27 18298 13.34 55.89 Picoxystrobin + Asana 6, 9.6 R1  Mix 4.25 10093 13.08 62.29 Picoxystrobin + Asana 6, 9.6 R3 Mix 3.37 5761 12.88 56.46 LEM-17 + Asana 16, 9.6 R1  Mix 1.53 6993 13.35 54.82 LEM-17 + Asana 16, 9.6 R3 Mix 3.37 2794 13.18 58.48 Headline + Asana 6, 9.6 R3 Mix 1.47 4626 13.22 56.08 Headline (R3) + Asana** (IPM) 6, 9.6 R3 + IPM R3 + IPM 2.17 13828 13.39 60.73 Asana** 9.6 IPM IPM 6.52 8683 13.41 59.12 Non-treated control 4 - - 5.93 22577 12.99 58.61 *CAD = Cumulative aphid days. **Threshold of 250 aphids/plant; Asana was assigned as the IPM insecticide.  

Fungicide-Insecticide Study on Soybeans

This study was designed to optimize insecticide and fungicide usage on soybeans by comparing different products applied at different timings. To explain yield responses, foliar disease severity and aphid populations were assessed throughout the season.</p

Iowa State University, Northwest Research Farm and Allee Demonstration Farm ISRF08-29, 31  28 Fungicide-Insecticide Study on Soybeans  Nathan Bestor, research associate Daren Mueller, extension specialist Alison Robertson, assistant professor Department of Plant Pathology Rebekah Ritson, graduate assistant Matt O’Neal, assistant professor Department of Entomology Palle Pedersen, assistant professor Department of Agronomy  Introduction This study was designed to optimize insecticide and fungicide usage on soybeans by comparing different products applied at different timings. To explain yield responses, foliar disease severity and aphid populations were assessed throughout the season.  Materials and Methods Plots were established on July 9, 2008. Plot size was four 30 in. rows by 35 ft long. The field was set up in a randomized block design with five replications.  Fungicides and insecticides were sprayed either alone or in combination at growth stage R1 or growth stage R3. Two controls were included. One was a non-treated control and the other was an IPM-based control that used the 250 aphid threshold to trigger an insecticide application (Table 1). The  R1 sprays were on July 9 and the R3 sprays were on July 31, 2008.    Data were collected for foliar disease three times during the summer. The upper and lower canopies were assessed for percent coverage of foliar disease caused by fungal pathogens. Because of low disease pressure, only the last assessment (August 27, 2008) was included in Table 1. Aphids were assessed on all treatments regularly throughout the summer and are reported as Cumulative Aphid Days (CAD). Before harvest, stems from selected treatments were rated for anthracnose stem blight. Finally, grain yield (adjusted to 13% moisture), moisture, protein, and oil were recorded.   Results and Discussion Aphid populations at the Sutherland farm were heavy and IPM control plots reached economic threshold by July 31, 2008 and were sprayed.  Preliminary results indicate that insect and disease pressure was greater in plots receiving R1 sprays compared with R3 sprays. In nearly every case an R1 treatment had more disease or aphid pressure than an R3 treatment  (Table 1). This suggests that insect and disease pressure did not start until well after the R1 application, so these products were not able to manage the pests.  Yields reflect these results by showing similar differences between R1 and R3 sprays.   This project will continue for the next three growing seasons. We will continue to look at the interaction between insecticides and fungicides to optimize the use of these products on soybean.   Acknowledgements Thanks to Ryan Rusk, Northwest Farm superintendent, and Josh Sievers, ag specialist, for their cooperation and assistance with this study. This work was funded, in part, by soybean checkoff funds from the Iowa Soybean Association.        Iowa State University, Northwest Research Farm and Allee Demonstration Farm ISRF08-29, 31  29        Table 1. Fungicides and insecticides applied at growth stages R1 and R3 and resultant disease and insect pressure and yield response.  Treatment Application timing Brown spot in lower canopy (%) Cercospora leaf blight in upper canopy (%) Anthracnose stem blight (%) Cumulative aphid days (CAD)* Protein (%) Oil (%) Moisture (%) Yield (bu/A) Stratego Pro R1 4.20 6.62 1.44 55476 34.20 18.96 11.38 38.35de Stratego Pro R3 4.12 6.30 0.89 60877 34.06 19.07 11.06 40.21cd Punch R1 6.94 6.98 . 50316 34.10 19.00 11.16 37.12de Punch R3 6.58 5.18 . 47188 33.77 19.16 11.18 38.18de Headline R1 5.60 2.90 . 40140 33.90 19.12 11.21 37.40de Headline R3 3.58 4.98 . 31748 34.06 19.04 11.10 42.93c Leverage R1 6.36 4.76 . 52087 33.82 19.09 11.02 48.51b Leverage R3 5.32 1.30 3.40 17472 33.47 19.11 11.14 55.36a Asana R1 5.28 0.78 . 16436 33.70 19.02 11.14 48.61b Asana R3 5.06 0.76 . 12470 33.35 19.11 11.14 56.62a Stratego Pro +    Leverage R1 3.26 1.84 2.28 23930 33.66 19.12 11.22 49.84b Stratego Pro. +    Leverage R3 2.54 1.14 0.35 9062 33.45 19.08 11.46 57.68a Punch + Asana R1 7.60 2.12 . 23071 33.22 19.14 11.22 51.28b Punch + Asana R3 5.12 2.46 . 5271 33.49 19.09 11.08 56.39a Control -- 7.40 8.22 5.40 92281 33.70 19.24 11.20 35.66e IPM* -- 5.40 3.38 . 29331 33.31 19.01 11.08 56.75a *Threshold of 250 aphids/plant; Asana was assigned as the IPM insecticide 

This study was designed to optimize insecticide and fungicide usage on soybean by comparing different products applied at different timings. To explain yield responses, foliar disease severity and aphid populations were assessed throughout the season.</p

Iowa State University, Armstrong and Neely-Kinyon Research and Demonstration Farms ISRF08-12  33 Fungicide-Insecticide Study on Soybeans  Nathan Bestor, research associate Rebecca Ritson, graduate assistant Daren Mueller, extension specialist Alison Robertson, assistant professor Matt O’Neal, assistant professor Palle Pedersen, assistant professor Department of Agronomy  Introduction This study was designed to optimize insecticide and fungicide usage on soybean by comparing different products applied at different timings. To explain yield responses, foliar disease severity and aphid populations were assessed throughout the season.  Materials and Methods Plots were established on July 2, 2008. Plot size was four 30-in. rows by 35 ft long. The field was set up in a randomized block design with five replications.  Fungicides and insecticides were sprayed either alone or in combination at growth stage R1 or growth stage R3. Two controls were included, one was a non-treated control and the other was an IPM-based control that used the 250 aphid threshold to trigger an insecticide application (Table 1). The R1 sprays were on July 2 and the R3 sprays were on July 30, 2008.  Data were collected for foliar disease three times during the summer. The upper and lower canopies were assessed for percent coverage of foliar disease caused by fungal pathogens. Because of low disease pressure, only the last assessment (August 25) was included in Table 1. Aphids were assessed on selected treatments regularly throughout the summer and are reported as Cumulative Aphid Days (CAD). Before harvest, stems from selected treatments were rated for anthracnose stem blight. Finally, grain yield (adjusted to 13% moisture), moisture, protein, and oil were recorded.   Results and Discussion Aphid populations at the Armstrong Farm never reached economic threshold before growth stage R5 so the IPM treatment was not sprayed.   Preliminary results indicate that insect and disease pressure was greater in plots receiving R1 sprays compared with R3 sprays. In nearly every case an R1 treatment had more disease or aphid pressure than an R3 treatment  (Table 1). This suggests that insect and disease pressure did not start until well after the R1 application, so these products were not able to manage the pests.   Yields reflect these results by showing similar differences between R1 and R3 sprays.  This project will continue for the next three growing seasons. We will continue to look at the interaction between insecticides and fungicides to optimize the use of these products on soybean.  Acknowledgements Thanks to Bernie Havlovic, Armstrong Farm superintendent, and Jeff Butler, ag specialist, for their cooperation and assistance with this study. This work was funded, in part, by soybean checkoff funds from the Iowa Soybean Association.           Iowa State University, Armstrong and Neely-Kinyon Research and Demonstration Farms ISRF08-12  34        Table 1. Fungicides and insecticides applied at growth stages R1 and R3 and resultant disease and insect pressure and yield response.  Treatment Application timing Brown spot in  lower canopy (%) Cercospora leaf blight in upper canopy (%) Anthracnose stem blight (%) Cumulative Aphid Days (CAD)* Protein (%) Oil (%) Moisture (%) Yield (bu/A) Stratego Pro R1 2.2 11.8 4.95 7,724 34.9 18.3 12.36 50.9 Stratego Pro R3 4.0 8.2 1.40 3,994 34.3 18.5 12.32 51.4 Punch R1 3.4 13.1 . . 34.9 18.1 12.24 48.5 Punch R3 5.0 17.3 . . 34.7 18.2 12.42 49.9 Headline R1 1.9 6.5 8.50 . 34.3 18.6 12.48 50.3 Headline R3 2.3 9.7 1.55 . 34.9 18.1 12.28 50.2 Leverage R1 4.4 9.0 13.85 5,196 34.8 18.3 12.4 49.6 Leverage R3 1.9 9.5 11.40 2,088 34.2 18.4 12.42 53.7 Asana R1 3.6 5.6 . . 35.3 18.2 12.24 51.2 Asana R3 3.4 5.1 . . 34.1 18.6 12.50 51.5 Stratego Pro + Leverage R1 2.4 17.7 7.25 9,315 34.8 18.3 12.50 48.0 Stratego Pro. + Leverage R3 1.5 11.4 2.70 1,217 34.1 18.8 12.70 53.3 Punch + Asana R1 3.7 18.8 . . 35.0 18.2 12.32 50.4 Punch + Asana R3 2.6 9.2 . . 34.3 18.6 12.40 54.1 Control -- 4.2 12.3 9.40 12,832 35.3 17.9 12.38 48.6 IPM* -- 4.6 5.6 . 3,692 35.0 18.3 12.32 46.8    *Threshold of 250 aphids/plant; Asana was assigned as the IPM insecticide.  

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1616&amp;context=farms_reports

Fungicide-Insecticide Study on Soybeans

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Digital Repository @ Iowa State University (ISU)

Digital Repository @ Iowa State University (ISU)

Digital Repository @ Iowa State University (ISU)