Hosts:
Symptoms: Trapped heads and curled leaves.
Look-alike symptoms:
1) Hail injury: To distinguish, examine stems for hail bruised areas which first appear white and later turn brown and necrotic(1).
2) Frost injury
3) Wind injury
Favorable conditions: Misapplication, drift, or residual carryover (1). Conditions that increase chances of drift include: wind speed, temperature inversion, high sprayer pressure, small droplet size, worn nozzles, and others (2).
Pattern in field:
Infestation levels:
History in MT and US:
Crop losses:
Controls: Check equipment before going into the field. When replacing equipment consider using drift-reducing nozzles or a shielded boom (2).
References: 1) MPHR 7/2/80 2) NDSU Pest Report. "Spray drift problems beginning", June 5, 1992, No. 6.