Wind effects may be the most common environmental injury that I see in Nebraska and Wyoming. Wind injury appears in several forms and the degree of injury depends on the strength and duration of the wind.
Leaves injured by lesser winds appear as bronzed areas, brown with a shiny surface. The bronzing is due to the rubbing of leaves against each other. The bronzed areas tend to be brittle from drying out. When pressed, they crack forming a sharp-edged rip through the affected tissue. With higher winds, leaves not only bronze but tatter. Tattered leaves have a quarter to an inch sized tears with irregular brownish borders. Usually, leaf tissue does not hang from the tears and the edges of the leaflets show more tatter then inside the blade.
Stems may also be affected by winds. When exposed to milder winds, the stem may have just flopped around causing a slight weakness. With stronger winds, the vine may actually twist a bit casing a break or hinge-like weakness. If exposed to strong winds for several hours, the vine may actually twist all the way around, 360 degrees. This causes an irreversible pinch point in the stem. Under close examination, one may see the twist, and when the pinch point is cut open longitudinally, one will see that the xylem of the vascular tissue has enlarged and thickened forming Abrace wood@ tissue against the wind. This brace wood presses against and may collapse the phloem in the vascular tissue cutting off nutrient flow between the vine and the tubers.
An effect of these symptoms is to reduce tuber growth and lower yields.
Wind damage -- leaf tatter Wind damage -- vine
Wind damage -- pinch Wind damage -- brace wood
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