Herbicide Injury Symptoms

Herbicides Which Affect Seedling Growth:
Inhibitors of Cell Division

Common Herbicides in the Group:

• trifluralin (Treflan)

• oryzalin (Surflan)

• benefin (Balan)

• pendimethalin (Prowl, Stomp)

• prodiamine (Endurance)

• thiazopyr (Visar)

• dithiopyr (Dimension)

• napropamide (Devirnol)

• bensulide (Prefar, Betasan)

• DCPA (Dacthal)

• pronamide (Kerb)

How Applied:

All of these herbicides are soil applied with limited movement in the soil.

Movement in the Plant:

Translocation within plants is limited and herbicidal action takes place near the point of absorption.

Mode of Action:

Most herbicides in this group disrupt mitosis and produce stunted plants with swollen root tips. Napropamide, bensulide and pronamide stop cell division before mitosis resulting in limimted root growth.

Common Symptoms:

Stunting and swollen growth tips, sometimes swollen stems.

Effects of Inhibitors of Cell Division

The corn plant shown here emerged in soil treated with dithiopyr. The plant is stunted and has roots which are stubby and swollen at the tips.

The bean plant on the right emerged from soil which had been treated with trifluralin. The plant is stunted with a greatly reduced root system.

Excess levels of some of these herbicides applied at or near the soil surface can result in a swelling of the stem. This monterey pine has a region of thickened, enlarged tissue near the soil line as a result of treatment with oryzalin.