Herbicide Symptom Key

I. Herbicide applied exclusively to the soil - injury appeared as the weed/crop emerged or did not emerge

Symptoms:

Cell division inhibitors - General symptoms include stunted plants with abnormally thick, short roots with swelled root tips. Injured plants may not emerge at all or do not fully emerge. Grass shoots are short and thick and may appear red or purple in color. Broadleaf plants may have swollen and cracked hypocotyls. Tolerant species, typically large seeded species, emerge and are temporarily stunted due to slow root development.

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Shoot cell division/cell elongation inhibitors resulting in shoot malformation - Symptoms are stunted plants with twisted shoots and dark green leaves. Seedlings fail to emerge or exhibit poor emergence from the soil. Grasses may fail to emerge from the coleoptile properly or grass leaves may not properly unfurl. Broadleaves may have crinkled or puckered leaves or a shortened midvein, or leaf buds may not open.

Other cell division abnormalities - symptoms are a lack of weed/sensitive crop emergence

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Caroteniod pigment inhibitors - plants emerge a pale green but tissue rapidly turns chlorotic and white, and eventually necrotic; plants are stunted. Caroteniod pigment inhibitors are absorbed by roots and translocated in the xylem along with water to leaves.