Synthetic auxin growth regulators

Family: phenoxyacetic acid

Example: 2,4D (many product names)

Family: benzoic acid

Example: dicamba (Banvel, Clarity)

Crop Uses: small grains, corn, pasture

Movement: downward through plant (phloem)

Injury by auxin-types -- fiddle neck

Potato Injury: As auxins, these promote cell enlargement in the vascular tissue resulting in clogging and inhibition of translocation. Plants exposed to phenoxyacetic acids exhibit twisting stems (epinasty) due to asymmetrical growth. Leaves will malform appearing cup-shaped, crinkled, strapped, and having parallel veins. Leaves of dicamba-exposed plants have a "fiddle-neck" appearance, or a folded or hooded appearance. Curling of some petioles and leaves may occur along with the puckered appearance. Symptoms may occur within a few hours to several days. Yields are reduced but there are little affects on tuber appearance.

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