Field Guide for Integrated Pest Management in Hops

Weed ManagementRobert ParkerWeeds have many definitions. Inhop yards they are plants that interfere insome way with production, whether directlyimpacting the growth and yield of theplants themselves or indirectly inhibitingproduction by interfering with fieldoperations.Weeds compete with hop plants fornutrients, water, and—to some extent—light. Hop by nature grows tall, thereforecompetition for light is usually not as greata problem as it can be with most row crops.Some weeds also provide an environmentfor certain pathogens to survive when hopplants are not actively growing. Generallyspeaking, as weed density increases in thehop yard, yields decrease. Therefore weedmanagement must be considered in anoverall integrated pest management programin hops.Hop is a perennial crop and weedscan be a problem year around. Summerannual weeds, those germinating in thespring or summer, are found in the growingcrop. They can interfere with sprayingoperations, distort sprinkler patterns insprinkler-irrigated yards, and interfere withharvest. However, winter annual weeds,those germinating in the late summer orfall, usually do not have much direct impacton hop growth. Winter annual weeds can,however, cause indirect problems in hopyards by depleting stored soil moisture,interfering with hop yard maintenanceduring the off season, and slowing springfield operations. Perennial weeds, thoseplants that live more than two years, cancreate problems similar to those posed byannual weeds. Perennials are much moredifficult to control and are frequently spreadwith tillage operations.A few representative annual andperennial weeds are pictured in Figures 142to 148. The pages following contain basicinformation on planning and executing anintegrated weed management program inhops as well as photos of many of the weedsthat can be problematic in hop yards.69RepresentativePerennial WeedsRepresentative Annual WeedsTOP ROW, LEFT TO RIGHT: Figure 142. Prickly lettuce. Figure 143. Common lambsquarter.BOTTOM ROW, LEFT TO RIGHT: Figure 144. Kochia. Figure 145: Puncturevine. (R. Parker)FROM TOP:Figure 146: Canada thistle.Figure 147: Field bindweed.Figure 148: Blackberry.(R. Parker)