Ash Flower Gall

Scientific Name: Eriophyes fraxinivorus

Ash flower gall is initiated by the feeding of microscopic mites on the male flowers of ash trees. Control of this pest is quite limited. The galls do not affect tree health, but are considered unsightly.

Attacks: Green ash, white ash

What you will see:

• Ball-like irregular masses
• Current years galls are green early in the season
• Old galls are reddish-brown
• Gall masses persist for up to two years

Life cycle:

• Mites begin feeding on the male flower clusters of ash
• Mite feeding initiates gall formation of flower tissue
• Female mites then lay eggs in the developing galls
• Mites are too small to be seen with the unaided eye
• Female mites spend the winter under bud scales or bark

Cultural Management of Ash Flower Gall

Cultural practices:

• Galls do not harm the health of infested trees
• Once a gall starts growing it will continue to form even if the mite dies
• Increase acceptance of galls by consumers
  • Galls create additional visual structure in winter
• Add color in late season

Insecticides can be used to “reduce” gall numbers