Hop Cones: Healthy (Left); Aphid damage (Mold)(Right)

Hops are a specialty crop used for bittering and flavoring beer. All beer may contain two types of hops. Bittering hops are used to make beer more bitter. Aroma hops are used for flavoring. …Mature hop cones contain numerous lupulin glands, which contain the important brewing constituents of alpha-acids, beta-acids and essential oils.

The hop aphid is native to Europe. the hop aphid first appeared in the U.S. in 1863 and ruined the crop in many eastern states with reported yield losses of 90%.

Aphids feed directly on hop plants, extracting cell sap and nutrients with their sucking mouthparts. high aphid populations reduce yields and seriously weaken plants. Hop aphids excrete prolific amounts of honeydew. Honeydew is plant cell sap, composed of sugars passed through the aphid’s digestive system. Sooty mold grows on the honeydew and can destroy a crop’s value, as mold renders hop cones unacceptable for brewing.

“Damson-hop aphid (Phorodon humuli Schrank) is a serious problem in all hop-growing districts of the Northern Hemisphere. If uncontrolled it is capable of completely destroying the crop. In the past aphids severely influenced hop and both its quality and quantity depended on the activity of their natural enemies. …Together, such natural enemies can provide satisfactory control of aphid populations, provided that the environmental conditions are more favorable for the natural enemies than to aphids.

On the other hand it is necessary to realize that hops free from damage caused by pests and diseases in commercial hop gardens will be hardly possible to produce without efficient insecticides, miticides and fungicides.”

Author: Vostrel, J.
Affiliation: Hop Research Institute, Czech Republic.
Title: Negative Effect of Fungicides Used in Practical Hop Production Against Downy Mildew (Pseudoperonospora humuli) on Aphidophagous Coccinellids Propylea quatuordecimpunctata L.
Source: Acta Hort. 2013. 1010:109-112.