Setting up a Corn and Soybean Herbicide Program with Cover Crops - Dr. Jeff Stachler, OSU Extension, from the 2020 Conservation Tillage and Technology Conference, held March 3-4, 2020, Ada, OH, USA.
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Dr. Jeff Stachler - Setting up a Corn and Soybean Herbicide Program with Cover Crops
1. Setting up a Corn and
Soybean Herbicide Program
with Cover Crops
Jeff Stachler
Extension Educator
3-3-20 (2020 CTC)
2. โข Injury / death of cover crop
โข Herbicide residues for feed
โ Crop rotation restrictions must be followed
โ Label is a legal document
โ Few species can be planted for feed for
certain products
Two reasons for crop rotation
3. โข Length of time herbicide remains active in
soil.
โข Driven by disappearance or breakdown of
herbicide.
โข Factors affecting persistence.
โ Soil factors
โ Climatic conditions
โ Herbicidal properties
Soil persistence / Soil residual life
From: Persistence of Herbicides in Soil; 1-1-99; Curran; Penn State Extension
4. โข Soil composition
โ Soil texture
โข Clay
โ Organic matter
โข Soil chemistry
โ Soil pH
โข Too high
โ Atrazine and some ALS herbicides
โข Too low
โ Imadazolinones
โ Chemical and/or microbial breakdown
โข Moisture, temperature, pH, oxygen, and mineral nutrient
supply drive microbial breakdown
Soil factors
5. โข Moisture
โ Biggest driver
โ Both microbial and chemical breakdown
โข Temperature
โ Warmer temperature more microbial and
chemical breakdown
โข Sunlight
โ Chemical and/or microbial breakdown
โข Moisture, temperature, pH, oxygen, and mineral
nutrient supply drive microbial breakdown
Climatic factors
6. โข Water solubility
โ Leaching occurs when herbicide is dissolved
in water and moves downward in soil profile
โข Vapor pressure
โ Herbicide changes from liquid or solid to gas
โข Chemical structure
Herbicide properties
8. โข Chlorimuron (Classic, Canopy, Authority MAXX,
Authority XL / Zone, Cloak, Canopy Blend,
Canopy EX / Cloak EX / Fallout, Enlite, Envive,
Fierce XLT, Synchrony XP, Trivence, Valor XLT)
โ 18 months
โข Radish
โข Kale
โข Rape
โข Turnip
โข Mustards
โข Buckwheat
โข Sunflower
โ 12 months
โข Legumes
Herbicides with extra long rotation
Over 7 pH, then maybe longer
9. โข Cloransulam (FirstRate, Authority First /
Sonic, Surveil)
โ 30 months
โข Sunflower
โ 18 months
โข Rape
โข Other mustard species
โข Buckwheat
โ 12 months
โข barley
Herbicides with extra long rotation
10. โข Sulfentrazone (Spartan, Authority Assist /
Sulfentrazone Assist, Authority First / Sonic,
Authorit MAXX, Authority MTX, Authority XL /
Zone, Authority Supreme)
โ 24 months
โข Rape
โข Other mustard species
Herbicides with extra long rotation
11. โข fomesafen (Flexstar, Flexstar GT, Marvel,
Prefix, Torment, Warrant Ultra)
โ 24 months
โข Rape
โข Other mustard species
Herbicides with extra long rotation
12. โข Glyphosate + ALS โ resistant
โ marestail
โข Glyphosate + ALS + PPO โ resistant
โ Common ragweed
โ Giant ragweed
โ Waterhemp
Weed control assumptions
13. โข Burndown
โGlyphosate + Sharpen/Zidua PRO + 2,4-D (+ metribuzin)
โGramoxone (4 pt) + 2,4-D + metribuzin
โGlyphosate + dicamba (Xtend soybeans)
โGlyphosate + dicamba + Sharpen (Xtend soybeans)
โGlufosinate + Sharpen + metribuzin
โGlufosinate + 2,4-D + metribuzin
โข Control in spring without a fall application
Winter cereal grain species - soybean
14. โข PRE
โ All can be used
โข Slight concerns
โ Authority First / Sonic
โ Metribuzin
โ Metolachlor
โ Pyroxasulfone (maybe largest concern)
โ Prefix
โ Especially with dry weather
Winter cereal grain species - soybean
15. โข POST
โ Glyphosate + dicamba (Xtend soybean)
โ Glufosinate + 2,4-D (E3 soybean)
โ Glufosinate (LL, E3, and GT27 soybeans)
โ Glyphosate + 2,4-D (E3 soybean)
โข Weakest on waterhemp and marestail
โ Assure II / Targa not likely (120 days)
โ Clethodim (30 days)
โ Fusilade
โ Flexstar and Cobra if no PPO resistance
Winter cereal grain species - soybean
16. โข Burndown
โGlyphosate + Sharpen + 2,4-D (+ metribuzin)
โGramoxone (4 pt) + 2,4-D + metribuzin
โGlyphosate + dicamba (Xtend soybeans)
โGlyphosate + dicamba + Sharpen (Xtend soybeans)
โGlufosinate + Sharpen + metribuzin
โGlufosinate + 2,4-D + metribuzin
โข Control in spring without a fall application
Tillage radish and other mustard species - soybean
17. โข PRE
โ Spartan
โข Slight concerns based upon label
โ Valor
โ Metribuzin
โ Metolochlor
โ Pyroxasulfone
Tillage radish and other mustard species - soybean
18. โข POST
โ Glyphosate + dicamba (Xtend soybean)
โ Glufosinate + 2,4-D (E3 soybean)
โ Glufosinate (LL, E3, and GT27 soybeans)
โ Glyphosate + 2,4-D (E3 soybean)
โข Weakest on waterhemp and marestail
โ Assure II / Targa not likely
โ Clethodim
โ Fusilade
โ Cobra if no PPO resistance
Tillage radish and other mustard species - soybean
19. โข Burndown
โGlyphosate + Sharpen + 2,4-D (+ atrazine 1.5 lb ai/A)
โGramoxone (4 pt) + 2,4-D + atrazine 1.5 lb ai/A
โGlufosinate + Sharpen + atrazine 1.5 lb ai/A
โGlufosinate + 2,4-D + atrazine 1.5 lb ai/A
โข Control in spring without a fall application
Winter cereal grain species - corn
20. โข PRE
โ All can be used
โข Slight concerns
โ Pyroxasulfone (maybe largest concern)
โ mesotrione
Winter cereal grain species - corn
21. โข POST
โ All HPPD herbicides
โ Clopyralid
โข Not waterhemp
โ Dicamba
โ 2,4-D
โ Glufosinate (LL corn)
โ Slight concerns
โข Mesotrione
โข Tembotrione
Winter cereal grain species - corn
22. โข LL corn
โ Glufosinate 32 to 43 fl oz/A
โข RR + LL corn
โ Glufosinate 32 to 43 fl oz/A
โ + glyphosate 1.125 lb ae/A
โข Maybe for cereal rye not for feed apply 1.5
oz/A flumioxazin 7 days before planting
โข If planting broadleaf and grass crop, then no
PRE herbicide, especially if used for feed
Herbicide programs for inter-seeding cover crop
into corn
23. 1. Look at label to determine if herbicide can be
used on cover crops for feed.
2. Must control the troublesome weeds without
injuring or killing cover crop
Summary
27. Herbicide applications in 2,4-D-resistant soybean
Treatment 49 DAT (6-26) 28 DAT POST
0 fb Cheetah 0 f
0 fb Roundup 0 f
0 fb Cheetah + Enlist One 0 f
0 fb Roundup + Enlist One 0 f
Valor fb Cheetah 54 e
Valor fb Roundup 58 de
Valor fb Cheetah + Enlist One 61 d
Valor fb Roundup + Enlist One 58 de
Fierce XLT fb Cheetah 78 bc
Fierce XLT fb Roundup 73 c
Fierce XLT fb Cheetah + Enlist One 74 c
Fierce XLT fb Roundup + Enlist One 81 ab
Authority Supreme fb Cheetah + Enlist One 87 a
28. Herbicide applications in 2,4-D-resistant soybean
Treatment 49 DAT (6-26) 28 DAT POST
0 fb Cheetah 0 f 51 d
0 fb Roundup 0 f 10 f
0 fb Cheetah + Enlist One 0 f 80 bc
0 fb Roundup + Enlist One 0 f 74 c
Valor fb Cheetah 54 e 85 ab
Valor fb Roundup 58 de 23 e
Valor fb Cheetah + Enlist One 61 d 94 a
Valor fb Roundup + Enlist One 58 de 90 ab
Fierce XLT fb Cheetah 78 bc 45 d
Fierce XLT fb Roundup 73 c 9 f
Fierce XLT fb Cheetah + Enlist One 74 c 84 ab
Fierce XLT fb Roundup + Enlist One 81 ab 94 a
Authority Supreme fb Cheetah + Enlist One 87 a 92 a
29. โข PRE (high rates & 2 to 4 aiโs) fb 1 POST
โ Soybean injury likely
โ May need a 2nd POST
โข PRE fb 2 POST
โ Same POST herbicide will lead to resistance
โ 2nd POST may be too late for soybean stage
โข Liberty = R1; dicamba = R1; fomesafen = R1 and only
one application; Enlist One = R2
โข PRE fb POST + Residual
โ Need rain to active
โ Existing plant MUST be controlled
Herbicide strategies
30. โข Site 14 (PPO)
โ Flumioxazin (2.5 oz), sulfentrazone (8 fl oz)
โข Site 5 (PSII)
โ Metribuzin (8 oz/A / 12 fl oz)
โข Site 15 (mitosis inhibitor)
โ Metolachlor (1.5 pt), acetochlor (1.5 qt), pyroxosulfone
(4.08 fl oz), dimethanamid (18 fl oz)
โข Site 7 (PSII)
โ Linuron (1.5 to 2 lb/A)
โข Site 3 (Mitotic inhibitors)
โ Pendimethalin (2.4 pt)
PRE AIโs available
31. โข Glyphosate
โ Resistance in most populations
โข Fomesafen, lactofen, and acifluorfen
โ Resistance in some populations
โข Glufosinate
โ No resistance and not perfect
โข Dicamba
โ No resistance and not perfect
โข 2,4-D
โ Resistance in MO, IL, NE and not perfect
POST AIโs
32. โข Stage
โ 3rd trifoliate โ Dual II Magnum
โ 90 days PHI โ Dual Magnum
โ 5th trifoliate โ Outlook, Parallel
โ 6th trifoliate - Zidua
โ R2 โ Warrant
โข Maximum rate
โ Dual II Magnum - 2.5 pt/A
โ Parallel - 2.55 pt/A
โ Outlook โ 24 fl oz/A
โ Zidua โ 5.75 fl oz/A
โ Warrant โ 4 qt/A
Limitations with POST residuals
33.
34.
35. Why is giant ragweed difficult to manage?
๏Good amount of genetic diversity โ
monoecious
๏Germination period is increasing, especially
late
๏Too few effective herbicides in soybean
๏Timing of POST herbicides, not always
correct
๏Herbicide resistance
โ Sites 2, 9, 14
36. Strategy for giant ragweed in soybean
๏ PRE fb POST fb POST
๏ PRE contains the following
โ Chlorimuron / cloransulam /
imazaquin / imazethapyr
โ Flumioxazin ??
โ Metribuzin ??
โ Sulfentrazone = 0!
37. Strategy for giant ragweed in soybean
๏ PRE fb POST fb POST
๏ POST
โ Glyphosate
๏ฑResistance!!
โ Fomesafen / lactofen
๏ฑResistance!!
โ FirstRate ??
๏ฑResistance!!
โ Glufosinate
โ Dicamba
โ 2,4-D
38. Strategies for giant ragweed in corn
๏ PRE fb POST
โ Comprehensive PRE
๏ฑAtrazine (1.6 to 2) + Balance,
Callisto, Stinger or Acuron
โ POST
๏ฑStatus, DiFlexx, DiFlexx Duo +
atrazine (??)
๏ฑOthers โ Impact, Laudis,
Callisto, Shieldex + atrazine
39. Strategies for giant ragweed in corn
๏ Early POST only
โ Corvus + atrazine (high rate) to
< V2 corn
โ 3-4โ giant ragweed, < 12โ corn
๏ฑCapreno, Resicore, others +
atrazine, Acuron
โ Concerned about timing - yield
loss