Herbicide injury from glyphosate: a non-selective, systemic herbicide.
- Initially, new tissue chlorosis on most grasses and broadleaves.
- Chlorosis progresses to tip necrosis in 5 to 10 days.
- Necrosis of entire plant within 3 weeks.
- Woody plants or glyphosate resistant weeds may re-sprout.
- Re-sprouting tissue may be chlorotic, malformed, strap-shaped, witches broomed.
- In woody perennial weeds, symptoms may re-occur up to 3 years after exposure.
Plant Entry and Symptom Expression
Foliar applied and symplastically translocated throughout the plant. Root absorption is rarely possible, only in sand or other soilless substrates. Not volatile. Crop injury is most likely as a result of misapplication or spray drift.
Glyphosate injury may be confused with symptoms from:
- Desiccation – loss of cell turgor pressure; salt accumulation.
- Frost damage – non-selective injury to plant tops.
- Paraquat (gramoxone) – rapid burn-down of all above ground tissue; regrowth possible.
- ALS inhibitor herbicides may produce nearly identical chlorosis and tip die-back.
- In woody plants, strap-shaped distorted foliage may resemble auxin herbicide damage, ALS inhibitor herbicides, or plant virus (such as rose rosette virus).
Herbicide Mode of Action Category
WSSA / HRAC – 9
Applied Weed Science: Including the Ecology and Management of Invasive Plants (3rd Edition), Merrill Ross & Carol Lembi, pages 165, 170-172.
Publication date: Sept. 10, 2015
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