What does Roundup - Touchdown injury look like?

Corn in Mississippi

Glyphosate drift injury can be confused with Zorial or Command injury because low rates will turn foliage white. However, drift injury can be distinguished from soil active herbicides by the presence of a distinctive "banding pattern" on leaves.

Glyphosate Banding Pattern This photo shows a typical banding pattern which often results from slight Roundup - Touchdown drift on a young corn plant's leaves. Lower leaves show contact injury, either chlorosis (white tissue) or necrosis (dead tissue), on much of the leaf surface, while contact injury on subsequently higher leaves is closer to the leaf tip. Roundup - Touchdown herbicide drift injury may also produce "purple" injury symptoms which mimic phosphorus deficiency. How does Roundup "purpling" differ from P deficiency.
The banding pattern results from higher leaves being enclosed within the whorl when the drift occurred. This banding pattern is more evident when injury is relatively slight, so little herbicide translocation occurs within a leaf or in new leaves.

You may assess crop injury by observing the degree of chlorosis in new leaves emerging from the whorl over several days at least 2 weeks after the drift occurred. This is because it takes at least 10-14 days for the herbicide to translocate to the growing point, which is underground, and produce injury symptoms in the whorl. Cool growing conditions lengthen the interval required to evaluate plant health, because growth rate slows dependent upon temperature, particularly when soil temperatures are below 55 degrees Fahrenheit (like they were in early April until about 4/15/2000).

	This plant is severely injured and will not likely recover from the herbicide injury. New leaves and leaf sheaths are entirely chorotic, indicating translocation of the herbicide to the growing point, severely injuring it. Replanting will be necessary.
	This photo shows a severely injured plant taken at least four weeks after the herbicide drift. Although the plant is still alive, new leaves are entirely chorotic and not emerging from the whorl, indicating the growing point is severely stunted and will not recover. Replanting will be necessary.
	This plant is moderately injured and may or may not recover from the herbicide injury. The leaves emerging from the whorl show moderate chlorosis and substantially reduced width. Careful evaluation over the next week would be required to make a replant decision.
	Several new leaves are emerging from the whorl and show no chlorosis, indicating this plant has completely recovered from slight herbicide drift and will not likely have any negative effects from the superficial injury. Replanting is NOT necessary.

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