Last Week’s Frost Damage Update
Imed Dami & Diane Kinney
The Ohio State University
Current situation: The month-long stretch between mid-April to mid-May is the typical frost threat period
from southern to northern Ohio, respectively. Vineyards almost dodged the bullet without frost injury this
year until last week. On May 8th and 9th, minimum temperatures hovered around or dropped below 32oF in
several locations in Ohio. At that time, all grapevines had already broken buds and/or reached shoot growth
of more than 12” long. Since the new growth is sensitive to temperatures just below freezing, several
varieties, exposed to those temperatures, sustained injury. Table 1 shows the lowest temperatures (27.7oF to
36.9oF) recorded on May 8th at OARDC stations throughout the state. It appears that the northeast and
southwest regions experienced the coldest temperatures. Reports of injury to grapevines also corresponded
to those areas. Since the May 8th event was a radiative frost, its impact was sporadic and localized rather
than widespread.