Injury from wind, pelting rain or hail is usually visible only on the side of leaves that were facing prevailing winds during a storm. Spots develop that are typically 1-5 mm (0.06 – 0.2 in.) in diameter, white to yellow in color and round or irregular in shape. Although rain damage is rarely serious, hail damage may defoliate a crop. Storm damage may be confused with Botrytis leaf blight or herbicide injury and can also make plants more susceptible to fungal and bacterial pathogens.
Conditions for Disease Development
Raindrops, hailstones and soil particles blown by strong winds wound leaf, neck and flower stalk tissues.
In areas that are subject to storms, seed cereal crops with onions to act as a wind break. Once the onion seedlings are established use selective herbicides to kill the cereal crop. Spray broad spectrum fungicides on storm damaged plants to reduce the risk of secondary infections.