Hop Pests and Diseases

Many hop diseases and pests do not attack other species, and so their natural distribution is restricted to areas where hops are native. As a result, these diseases and pests are usually only a problem in the Northern Hemisphere

Table: Hop Pests and Diseases

Name

Type

Main effect on hop

Damson-hop aphid

Pest

Low yields, a sooty mould fungus grows on the aphid honeydew secretion which spoils cone appearance; can cause the cone to turn brown.

Red spider mite

Pest

Silver speckling and webbing is left on hop leaves and cones, which can lead to the cones turning reddish brown, and also to loss of crop.

Powdery Mildew

Disease

White powdery spots form on leaves and stems, which can turn red if untreated. Can cause serious losses if cones become infected.

Downy Mildew

Disease

Fungus causes stunted shoots and laterals, resulting in a serious reduction in vegetative growth and also in cone losses.

Verticillium Wilt

Disease

An infection initially produces yellow patches on the hop leaves, which become black as the tissue dies. Once a field is infected, the disease spreads rapidly and can affect entire growing areas.

Hop Mosaic Virus

Disease (virus)

Severe stunting of the bines; leaves show translucent banding along the veins and also curling. In addition to loss of cone yield, the virus can lead to a drop in α-acid content.

Hop Latent Virus

Disease (virus)

It is suggested that infection may reduce α-acid content.

Necrotic Ringspot Virus

Disease (virus)

Chlorotic rings or arcs appear, that can become necrotic. Cones and α-acids can be reduced by up to 50%.

In summary, not only do hop growers face challenges such as climate and day length, they also need to be wary of pests and diseases. Next, we look at the hop growing cycle.

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