Mountain Ash Berry Failure and Tip Dieback: Pollination and Twig Borer

Central Alberta Mountain Ash with flowers but no berries + annual tip dieback—likely pollination issue (self-sterile?) and twig borer infestation.

Berry Failure

• Many Sorbus require cross-pollination (different cultivar/seedling)
• Single tree = no pollen partner
• Bees needed—cold/wet bloom weather reduces flight
• Arborist/horticulturist for cultivar-specific advice

Tip Dieback

• Snip dead tip → check for borer hole just below dead zone
• 2-4mm hole = twig borer (moth/beetle larva)
• Healthy tree tolerates minor tip loss
• Systemic imidacloprid if severe

Climate Note

Alberta winters test hardiness. Ensure adequate snow cover or mulch for root protection.