Downy mildew has been identified as the primary pathogen plaguing our northeastern hop yards. This disease causes reduced yield, poor hop quality, and can cause the plant to die in severe cases. Control measures that reduce disease infection and spread while minimizing the impact on the environment, are desperately needed for the region. Mechanical control is one means to reduce downy mildew pressure in hop yards. Scratching, pruning, or crowning is a practice initiated in the early spring either before or at the time that new growth has just emerged from the soil.
Darby, Heather; Bruce, John; Gupta, Abha; Morin, Freddy; and Lewins, Scott Lewins, "Hop Crowning Trial Final Report" (2017). Northwest Crops & Soils Program. 60.