Wind effect on corn leaf azimuth

Stalk breakage, greensnap, in pretassel corn (Zea mays L.) increases when leaf azimuths are parallel to extreme thunderstorm winds. Yet wind effect on leaf azimuth is unknown. Azimuths recorded north of east-west windbreaks changed from 185° to 195° (north = 0°/360°; east = 90°; etc.) as distance from windbreaks increased from 1.4 to 13.6 H in 1999 in north-south rows; H is the average height of the tallest row of windbreak trees. Plants at 20 to 25 H are considered unsheltered. In 2000, leaf azimuth changed from 195° to 178° from 1.5 to 25 H in north-south rows. With higher wind speeds and east-west rows in 2002, azimuths ranged 194° to 202° from 3.7 to 23 H. In east-west rows windbreak sheltered leaves were oriented in north-south patterns. In contrast, unsheltered plants had few leaves pointing southward. Early-season wind altered corn leaf azimuth. This affects greensnap tolerance and perhaps other physiological traits.