**Fireblight (Erwinia amylovora)**

Caused by bacteria Erwinia amylovora
Onset in the spring as bacterial cells ooze in a yellow-amber liquid from existing cankers on infected plants
Bacteria spread to flowers, leaves, fruit, and stems by insects, wind, rain, or pruning equipment
Bacteria penetrates through pruning wounds and natural openings such as stomates and nectaries
Thrives in warm, wet weather in the spring
Twigs and branches die rapidly and appear scorched
Tender shoots droop and bend as they die, causing “shepherd’s crook“
Cankers later form at the base of branches, and susceptible plants die
Host plants: Rosaceae family – apple, crabapple, cotoneaster, hawthorn, mountain ash, pyracantha, pear
- Highly associated with host bloom period per crop

Improve plant vigor, but avoid heavy spring fertilization that can promote succulent growth
In late summer (when oozing no longer occurs), prune diseased wood 6-8 inches below the infection, sterilizing the tools between cuts
Remove waterspouts
Dispose of infected plant material
Replace susceptible varieties with resistant ones

Materials:

Contact bactericides:
- Copper [M01]: cuprous oxide, copper hydroxide, copper sulfate
- Phosphonates[P07]: fosetyl-Al
- Streptomycin sulfate [25]
Systemic fungicides:
- {DMI} Triazoles [3]: Myclobutanil, Propiconazole, Triadimefon, Imidazole
- Thiophanate methyl [M1]
Considerations:
- Do not apply group [P07] and copper-based [M01] fungicides within 14dof one another, as phytotoxicity is likely to occur! Rotation is critical to avoid resistance.