SOYBEAN
HERBICIDE INJURY DIAGNOSISPlanting/Emergence
Poor germination and uneven
emergence
- misapplication of 2,4-D
or Banvel for burn-down in the spring prior to soybean planting. Allow 7 and
30 days before planting after applications of 2,4-D ester at 1 pt/A and 1
qt/A, respectively.
- This is most severe sulfentrazone
(Authority First and Canopy XL) injury which can be caused by low organic
matter soils, high rainfall and cool temperatures.
Cotyledon/Young plant
Cotyledon burn, veinal chlorosis,
and/or stunted plants
- sulfentrazone (Canopy
XL and Authority First) injury with low organic matter soils, high rainfall
and cool temperatures.
Leaf crinkling/"bud seal"
- misapplication of Eradicane,
Eptam, or Sutan+ (shoot inhibitors)
Leaf puckering/shortened
midrib/"drawstring"
- excessive rates and/or
cold wet conditions following application of Axiom, Dual, Frontier or Lasso
(shoot inhibitors).
Leaf burn on older leaves
- wet conditions following
application of Lexone/ Sencor, or carryover of triazine herbicides (Atrazine,
Princep).
Leaf burn on young &
old leaves
- postemergence applications
of Blazer, Basagran, Cobra, Flexstar, Reflex or Resource. Crop oil concentrates
and other additives may increase injury.
Leaf puckering/cupping/epinasty
- growth regulators (2,4-D,
2,4-DB, Banvel, Clarity, Crossbow, Hornet, MCPA, Scorpion III, Stinger, Tordon).
Spray drift from nearby applications should follow wind channels. Hot, moist
conditions up to three days following application of a growth regulator may
lead to volatilization. Injury from volatilization may not reduce yields.
In some instances similar symptoms are present where a growth regulator can
be ruled out. Current theories explain this phenomenon as a plant hormone
response regulated in the apical meristem of the plant. This type of response
may be initiated as a result of plant stress coupled with or without postemergence
herbicide application. Effect on yield is probably minimal.
Stunted plants and/or interveinal
chlorosis
- potential carryover of
Exceed, especially under drought conditions following application of Exceed
and soil pH greater than 7.8.
Swollen or cracked hypocotyls/pruned
roots
- excessive rates of DNA
herbicides (Prowl, Sonalan, Treflan). Lateral roots may be short and thick.
Callused, yellow plants/purple
mid-veins
- usually associated with
"amino acid" inhibitors. Could result from misapplication of Accent, Beacon,
Basis, Basis Gold, Exceed, Permit, Roundup Ultra, Spirit or plant stress in
conjunction with the application of Classic, Firstrate, Pinnacle, Pursuit,
Raptor or Scepter. New growth will be the first to yellow. Severe injury will
result in death (browning) of stem pith tissue and eventual necrosis of leaf
tissue.
Bloom/Pod set
Speckled leaves
- spray drift from nearby
application of a cell membrane disrupter (paraquat).
Leaf puckering
- growth regulator type
herbicides (Banvel, 2,4-D, Stinger). Should not appear this late in the season,
but the possibility does exist. Refer to the discussion Cotyledon/Young plant
- leaf puckering /cupping /epinasty.
Corn,
Soybean, Wheat, and Alfalfa Field GuideBulletin 827