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Beginner

Scientific Name
            Colomerus vitis

Identification
Eggs

• Oval and white

Nymphs

• Resemble adults but smaller

Adults and Nymphs

• Whitish, wormlike
• About 0.2mm long
• Many adults found in colonies within galls

Damage

• Causes patches of concave, felty galls called erinea on the lower leaf surface
• Galls are whitish at first, becoming yellow and finally reddish brown
• Blisterlike swellings on the upper surface, may have a reddish tinge in red cultivars
• Severely infested leaves may drop in the fall somewhat earlier than non-infested leaves

Often Confused With
Downy mildew:  no blister-like bumps on upper surface of leaf

Phylloxera:  projecting galls on underside of leaf

Period of Activity
First galls are present in mid- to late May.  New galls can be produced as long as there is new susceptible leaf tissue.

Scouting Notes
Often first detected in areas near bush lots or areas with tall weeds but can be found throughout a vineyard once established.  Examine young leaves for galls.
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Threshold: Though severe injury is not common, young vines are particularly susceptible to injury that may impact establishment and vigour.  In mature vines, unless more than 25% of the vines have this injury present, specific treatment is not usually necessary.

Advanced

Scientific Name
            Colomerus vitis

Identification
Eggs

• Oval and white

Nymphs

• Resemble adults but smaller

Adults and Nymphs

• Whitish, wormlike
• About 0.2mm long
• Many adults found in colonies

Damage

• Causes patches of concave, felty galls called erinea on the lower leaf surface
• Galls are whitish at first, becoming yellow and finally reddish brown
• Blisterlike swellings on the upper surface, may have a reddish tinge in red cultivars
• Severely infested leaves may drop in the fall somewhat earlier than non-infested leaves

Often Confused With
Downy mildew:  no blister-like bumps on upper surface of leaf

Phylloxera:  projecting galls on underside of leaf

Biology
Adults overwinter under the bark and crawl out during the early summer to feed and reproduce on young leaves. Colonies of mites live inside the blisters (erinea) formed by their feeding on the lower surfaces. The blisters contain masses of enlarged tangled leaf hairs.  Inside the galls, the females lay eggs which hatch to produce nymphs.  When mature, nymphs (crawlers) emerge from the galls and move to new tissue and initiate new galls. Several generations occur every year with new galls developing nearest the growing shoot tip.  Beginning in late summer, adult mites move back to crevices in the bark for the winter.

Period of Activity
First galls are present in mid- to late May.  New galls can be produced as long as there is new susceptible leaf tissue.

Scouting Notes
Often first detected in areas near bush lots or areas with tall weeds but can be found throughout a vineyard once established.  Examine young leaves for galls.
.
Threshold: Though severe injury is not common, young vines are particularly susceptible to injury that may impact establishment and vigour.  In mature vines, unless more than 25% of the vines have this injury present, specific treatment is not usually necessary.

Management Notes
The best time for control is when shoots are growing or when new erinea are forming. 

Usually, little damage results from grape erineum mite, but an early extensive infestation, especially on young vines can produce serious stress on the vine. Sulphur helps control grape erineum mite and its regular use in a rotational disease management strategy usually minimizes the effects of erineum mite.