Slide Presentation
TITLE
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Peanut Response To Metribuzin
AUTHOR
L.C. Hand and
Eric P. Prostko
Professor and Extension Weed Specialist
University of Georgia
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TABLE OF CONTENTS
Peanut Response To Metribuzin
Introduction
Palmer Amaranth Biology
Field Corn: Post-Harvest Palmer Amaranth Populations Must be Managed!
Post-Harvest Control Option
Palmer Amaranth Burndown - 2019 (AMAPA 1-6" tall)
Issues
Issues - Rotational Restrictions listed on TriCor 4F Label
Objective
Hypothesis
Materials and Methods
Materials and Methods
Data Collected
Data Analysis
Data Presented
Results
Rainfall/Irrigation
Early Season Injury - 2017
Early Season Injury - 2017 - 280 g ai ha-1
Early Season Injury - 2017 - 140 g ai ha-1
Early Season Injury - 2017 - 70 g ai ha-1
Early Season Injury - 2018
Early Season Injury - 2018 - 280 g ai ha-1
Early Season Injury - 2018 - 140 g ai ha-1
Early Season Injury - 2018 - 70 g ai ha-1
Peanut Stand Loss - 2017
Peanut Stand Loss - 2018
Late Season Injury - 2017
Late Season Injury - 2018
Peanut Yield Loss - 2017 & 2018
Summary/Conclusions
Hypothesis
Future Research
Questions/Comments?
SLIDE CONTENTS
Peanut Response To Metribuzin L.C. Hand* and E.P. Prostko Department of Crop & Soil Sciences
Introduction Herbicide-resistant Palmer amaranth is one of the most troublesome weeds in agronomic crops in GA (Webster, ed. 2012; Webster, ed. 2013)
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)
Field Corn: Post-Harvest Palmer Amaranth Populations Must be Managed!
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)
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
Issues UPL (formerly UPI) released a Section 2(ee) recommendation for fall applications of metribuzin. Plantback intervals are listed for corn and soybean only.
Issues
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.
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.
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).
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
Data Collected Visual Estimates of Crop Injury 0 to 100% Peanut Plant Stand Reductions Peanut Yield Loss (%)
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
Data Presented Early and late season injury 2017 2018 Stand reduction 2017 2018 Yield 2017 and 2018 combined
Results
Rainfall/Irrigation 2017 2018
Early Season Injury – 2017 R2 = 0.98 I50 = 240.5 29 DAP
0 g ai ha-1 280 g ai ha-1 Early Season Injury - 2017
0 g ai ha-1 140 g ai ha-1 Early Season Injury - 2017
0 g ai ha-1 70 g ai ha-1 Early Season Injury - 2017
Early Season Injury - 2018 R2 = 0.83 I50 = 345.0 52 DAP
Early Season Injury - 2018 280 g ai ha-1 0 g ai ha-1
Early Season Injury - 2018 140 g ai ha-1 0 g ai ha-1
Early Season Injury - 2018 70 g ai ha-1 0 g ai ha-1
Peanut Stand Loss - 2017 R2 = 0.99 I50 = 252.6 31 DAP
Peanut Stand Loss - 2018 R2 = 0.91 I50 = 296.1 52 DAP
Late Season Injury - 2017 R2 = 0.97 I50 = 264.2 98 DAP
Late Season Injury - 2018 R2 = 0.87 I50 = 318.2 85 DAP
Peanut Yield Loss – 2017 & 2018 R2 = 0.74 I50 = 319.8 5,368 kg ha-1
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.
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
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
Questions/Comments?