Bacteria (Erwinia amylovora) generally cause blights during wet weather in early spring when buds are breaking. Fireblight of crabapples and mountain ash is favored by warm spring temperatures. In wet spring weather cankers formed during previous infections ooze droplets of bacteria. The bacteria are splashed by rain and blown by winds or insects may carry it to nearby plants.

The sudden death of flowers buds leaves young fruit and succulent shoots characterizes blight diseases. The blighted plant tissue is black and shriveled as though they were scorched with fire. Shoots often have a bent drooped tip resembling a shepherd's crook.

Plant resistant varieties. Avoid using high nitrogen fertilizers on susceptible cultivars.

Only fungicides containing copper may be effective against bacterial blights and bacterial disease but copper may burn foliage.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

Common Home Landscape Plants Susceptible to Fireblight:
 
Common Home Landscape Plants Resistant to Fireblight:
  • Crabapples (Malus)
  • ‘Adams’
  • ‘Beverly’
  • ‘Bob White’
  • ‘Camelot’
  • ‘Candied Apple’
  • ‘Centurion’
  • ‘Donald Wyman’
  • Malus floribunda
  • ‘Golden Raindrops’
  • ‘Harvest Gold’
  • ‘Henningii’
  • ‘Indian Magic’
  • ‘Indian Summer’
  • ‘Jewelberry’
  • ‘Mary Potter’
  • ‘Molten Lava’
  • ‘Ormiston Roy’
  • ‘Prairifire’
  • ‘Professor Sprenger’
  • ‘Silver Moon’
  • ‘Strawberry Parfait’
  • ‘Sugar Tyme’
  • ‘White Angel’
  • ‘Winter Gold’
  • M. zumi var. calocarpa
  • ‘Red Jewel’
  • ‘Ruby Luster’
  • ‘Sentinel.’
  • Pyracantha
  • ‘Mojave’
  • ‘Navaho’
  • ‘Teton’ and
  • ‘Shawnee’
     
  • Cotoneaster
  • Cotoneaster amoenus
  • C. adpressus
  • C. dammeri var. radicans
  • C. microphyllus
  • C. praecox and
  • C. zabelii
     
  • Hawthorn (Crataegus)
  • C. arnoldiana
  • C. coccinea
  • C. crus-galli
  • C. douglasii
  • C. phaenopyrum
  • C.prunifolia
  • C. punctata ‘Ohio Pioneer’
  • C. viridis ‘Winter King.’
 

 

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