Field Guide for Integrated Pest Management in Hops

Nutrient Management and ImbalancesDavid H. Gent79Several nutrients can occur at deficientor toxic levels in Pacific Northwest soils, andthe situation can be difficult to diagnose.Symptoms may be similar among variousconditions or may vary with the samecondition, depending on variety and theenvironment. General symptoms associatedwith nutrient imbalances are describedin this section, as well as known nutrientinteractions with diseases and arthropodpests. Fertilization recommendations varywidely in published literature, differingamong production regions, varieties,irrigation methods, soil pH, and seasons,therefore fertility recommendations are notprovided. Local experts should be consultedfor specific recommendations appropriate foryour hop yard.BoronBoron deficiency can result in delayedemergence of shoots, stunting, distortionand crinkling of young leaves (Fig. 205), andyellowing and death of shoot tips (Fig. 206).Leaves of affected plants may be small, brittle,and develop a fluffy-tipped appearance dueto impaired development of lobes (Fig. 207).Deficiencies are most common in acid soils.Boron deficiency has been suggested as acontributing factor for red crown rot.CalciumSymptoms of calcium deficiencydevelop first in young tissues and at growingpoints. Symptoms can be similar to borondeficiency, and may include yellowing ofgrowing points, reduced development ofleaves, and yellowing and death of leafmargins. Excessive calcium can interferewith uptake of other nutrients and inducedeficiencies in other positively charged ions(e.g., ammonium, magnesium, potassium).IronIron deficiency is first observed onyoung leaves as yellowing between veins,while veins remain green (Figs. 208 and209). Iron deficiency is most common inalkaline soils, although it can be inducedin highly acid soils (approximately pH 5.7or less) because of enhanced solubility anduptake of manganese.Figure 205. Stunting, distortion, and crinkling of young leavesassociated with boron deficiency. (J. Portner)Figures 206 and 207. Misshapen shoot tip and misshapen, “fluffy-tipped” leaf,both due to boron deficiency. (J. Portner, P. McGee)ABOVE: Figure 208. Close-up of yellowed leafdue to iron deficiency. (D. H. Gent)AT RIGHT: Figure 209. Yellowing of theyoungest leaves resulting from iron deficiency.Notice that symptoms are less pronounced onolder leaves. (J. Portner)