Slide Presentation

TITLE    (click title to view slides)

AUTHOR
L.C. Hand and Eric P. Prostko
Professor and Extension Weed Specialist
University of Georgia

DOWNLOAD PRESENTATION    (right click and select 'Save Target As...')

TABLE OF CONTENTS
  1. Peanut Response To Metribuzin
  2. Introduction
  3. Palmer Amaranth Biology
  4. Field Corn: Post-Harvest Palmer Amaranth Populations Must be Managed!
  5. Post-Harvest Control Option
  6. Palmer Amaranth Burndown - 2019 (AMAPA 1-6" tall)
  7. Issues
  8. Issues - Rotational Restrictions listed on TriCor 4F Label
  9. Objective
  10. Hypothesis
  11. Materials and Methods
  12. Materials and Methods
  13. Data Collected
  14. Data Analysis
  15. Data Presented
  16. Results
  17. Rainfall/Irrigation
  18. Early Season Injury - 2017
  19. Early Season Injury - 2017 - 280 g ai ha-1
  20. Early Season Injury - 2017 - 140 g ai ha-1
  21. Early Season Injury - 2017 - 70 g ai ha-1
  22. Early Season Injury - 2018
  23. Early Season Injury - 2018 - 280 g ai ha-1
  24. Early Season Injury - 2018 - 140 g ai ha-1
  25. Early Season Injury - 2018 - 70 g ai ha-1
  26. Peanut Stand Loss - 2017
  27. Peanut Stand Loss - 2018
  28. Late Season Injury - 2017
  29. Late Season Injury - 2018
  30. Peanut Yield Loss - 2017 & 2018
  31. Summary/Conclusions
  32. Hypothesis
  33. Future Research
  34. Questions/Comments?



SLIDE CONTENTS
  1. Peanut Response To Metribuzin L.C. Hand* and E.P. Prostko Department of Crop & Soil Sciences
  2. Introduction Herbicide-resistant Palmer amaranth is one of the most troublesome weeds in agronomic crops in GA (Webster, ed. 2012; Webster, ed. 2013)
  3. Palmer Amaranth Biology Wide germination window (Keeley et al. 1987) March-October Greatest germination from June-August Prolific seed production Over 446,000 seed per plant in non-crop (Webster and Grey 2015) Over 60,000 seed per plant when planted on August 1 (Keeley et al. 1987)
  4. Field Corn: Post-Harvest Palmer Amaranth Populations Must be Managed!
  5. Post-Harvest Control Option Metribuzin Good POST and residual control of Palmer amaranth (Crow et al. 2015; Grey et al. 2014) Takes pressure off of PPOs Can help reduce Palmer amaranth contributions to weed seed-bank ~30-60 day half-life (Shaner, ed. 2014) Microbial degradation and highly water soluble (Shaner, ed. 2014)
  6. Palmer Amaranth Burndown - 2019 (AMAPA 1-6” tall) NC-01-19 May 20 10 DAT NTC Gramoxone 3SL @ 840 g ai ha-1 Tricor 4L @ 280 g ai ha-1 Induce @ 0.25% v/v
  7. Issues UPL (formerly UPI) released a Section 2(ee) recommendation for fall applications of metribuzin. Plantback intervals are listed for corn and soybean only.
  8. Issues
  9. Objective Evaluate the response of peanut to various rates of metribuzin applied preemergence. Data will assist in reducing the plant-back interval on the Tricor® 4F label.
  10. Hypothesis Based on a targeted application rate of 280 g ai ha-1 and an estimated half-life of ~30-60 days, we hypothesize that rates of 70 g ai ha-1 or less (~two half-lives) should not negatively affect peanut growth and development.
  11. Materials and Methods Trials conducted in 2017 and 2018 in Ty Ty, GA ‘GA-06G’ peanut were planted in late April both years (twin-row).
  12. Materials and Methods Metribuzin was applied preemergence (two days after planting): 0, 35*, 70, 140, 280, 420, and 560 g ai ha-1 *35 g ai ha-1 rate not included in 2018 due to planting errors Treatments applied using a CO2-pressurized backpack sprayer 140 L ha-1 AIXR 11002 nozzles Plots were kept weed-free using labeled herbicides and hand-weeding Randomized Complete Block Design Four replications
  13. Data Collected Visual Estimates of Crop Injury 0 to 100% Peanut Plant Stand Reductions Peanut Yield Loss (%)
  14. Data Analysis Data were subjected to nonlinear regression using log-logistic analysis to describe a dose-response relationship Seefeldt et al. 1995 C = Lower limit D = Upper limit b = slope I50= dose giving 50% response Parameter estimates were obtained using PROC GLM in SAS 9.4 and graphed in SigmaPlot 14.0
  15. Data Presented Early and late season injury 2017 2018 Stand reduction 2017 2018 Yield 2017 and 2018 combined
  16. Results
  17. Rainfall/Irrigation 2017 2018
  18. Early Season Injury – 2017 R2 = 0.98 I50 = 240.5 29 DAP
  19. 0 g ai ha-1 280 g ai ha-1 Early Season Injury - 2017
  20. 0 g ai ha-1 140 g ai ha-1 Early Season Injury - 2017
  21. 0 g ai ha-1 70 g ai ha-1 Early Season Injury - 2017
  22. Early Season Injury - 2018 R2 = 0.83 I50 = 345.0 52 DAP
  23. Early Season Injury - 2018 280 g ai ha-1 0 g ai ha-1
  24. Early Season Injury - 2018 140 g ai ha-1 0 g ai ha-1
  25. Early Season Injury - 2018 70 g ai ha-1 0 g ai ha-1
  26. Peanut Stand Loss - 2017 R2 = 0.99 I50 = 252.6 31 DAP
  27. Peanut Stand Loss - 2018 R2 = 0.91 I50 = 296.1 52 DAP
  28. Late Season Injury - 2017 R2 = 0.97 I50 = 264.2 98 DAP
  29. Late Season Injury - 2018 R2 = 0.87 I50 = 318.2 85 DAP
  30. Peanut Yield Loss – 2017 & 2018 R2 = 0.74 I50 = 319.8 5,368 kg ha-1
  31. Summary/Conclusions Rates from 280-560 g ai ha-1 caused unacceptable injury and stand loss, resulting in 25-80% yield loss. The 140 g ai ha-1 rate resulted in a maximum of 17% visual injury and 10% stand loss, resulting in minimal yield loss (2%). Comparable injury levels, stand loss, and yield loss were observed at the 0, 35, and 70 g ai ha-1 rates. We conclude that metribuzin can be used as a post-harvest burndown treatment in corn with minimal injury, stand loss, and yield loss to a subsequent peanut crop.
  32. Hypothesis Based on a targeted application rate of 280 g ai ha-1 and an estimated half-life of ~30-60 days, we hypothesize that rates of 70 g ai ha-1 or less (~two half-lives) should not negatively affect peanut growth and development. FAIL TO REJECT
  33. Future Research Study repeated PPI applications A more accurate representation of carryover issues?? On-farm evaluations Burndown after corn harvest at multiple rates, plant peanut the next season and evaluate crop tolerance
  34. Questions/Comments?