What's eating my humulus lupulus?

Hops are seriously damaged by hop aphid and two-spotted spider mite — both are major concerns for growers. Downy mildew-associated damage can look pest-like, but true pests include aphids stripping shoot tips, spider mites causing extensive bleaching, and in North America, the hop looper caterpillar defoliating bines.

Dense colonies on shoot tips and undersides of leaves in summer; leaves curl and yellow; cones become contaminated and unmarketable. Introduce or encourage parasitic wasps (Aphidius spp.) and ladybirds; use insecticidal soap or pyrethrin spray early in infestation; remove overwintering eggs on prunus hosts nearby.

Widespread pale bronzing and stippling of leaves; fine webbing covers undersides; severe defoliation reduces cone yield. Apply predatory mite Phytoseiulus persimilis or Neoseiulus californicus; spray with horticultural oil or miticide; keep soil evenly moist and avoid drought stress.

Large irregular holes in leaves; defoliation of whole bines in heavy years; green caterpillars with pale stripes visible on foliage. Apply Bacillus thuringiensis (Bt) spray targeting young larvae; hand-pick; pyrethrin as a knock-down for severe outbreaks.

Ragged holes in young leaves near ground level in spring; silvery trails on stems and soil. Use ferric phosphate pellets around bine bases; lay bark mulch carefully to avoid hiding spots; hand-pick at night.