Lightening Damage to Grape Plants

by Dr. Dean Volenberg · October 30, 2012

This article is by Dr. Dean Volenberg of the University of Wisconsin’s Door County Extension. It was first published in the Wisconsin Grape Growers Association’s (WGGA) 30th July 2012 Vineyard IPM Scouting Report.

During July, I had the opportunity to examine a lightning strike injury to grape plants. The majority of vine damage was to shoots that were touching training wires in the VSP canopy (A). Damaged shoots had necrotic piths compared to healthy green shoots (B). Leaves displayed dark areas that resembled ozone injury or complete necrosis (see pictures page 3).

A dead giveaway that the damage was caused by lightning was that trellis wires were melted apart causing some minor collapse of the trellis. Fortunately the trellis wires were grounded which resulted in the electrical charge grounding out. One unique thing that I noticed walking into the damaged area was the smell of decomposing tissue. Since many of the shoots were damaged and weakened by the lightning, they will be removed to prevent secondary fungal infections. As a reminder botrytis likes to establish on tissues that are dead or decaying.