Fire Blight in Apples and Pears: Early Signs and How to Stop It

Fire blight is a bacterial disease that can kill blossoms, shoots, and — if it reaches the trunk — the entire tree in a single season. It spreads fast during warm, wet spring weather, right around bloom time, which makes early detection the difference between losing a few branches and losing the tree.

What to look for

• Blossoms and young shoots wilt and turn black or brown, as if scorched by fire (that's where the name comes from).
• Shoot tips curl into a distinctive shepherd's crook shape as they die back.
• A milky or amber-colored ooze may appear on infected bark in humid conditions — this is bacterial exudate, and it's the main way the disease spreads to pollinators and rain-splashed neighboring branches.
• Infected tissue often has a sharp, dark line where it meets healthy wood.

What to do if you see it

1. Prune infected wood immediately, cutting at least 8-12 inches below any visible symptoms into clean wood.
2. Disinfect pruning tools between cuts — a 10% bleach solution or rubbing alcohol works. Fire blight bacteria spread easily on blades.
3. Remove and destroy prunings away from the orchard; don't compost them.
4. Prune during dry weather, since wet conditions help the bacteria spread through fresh cuts.

Why rootstock choice matters before you even plant

The easiest way to reduce fire blight risk isn't treatment — it's prevention through rootstock selection. Older rootstocks, and highly vigorous ones, tend to be far more susceptible. Modern Geneva series rootstocks (G.11, G.41, G.214, G.890, and others) were bred specifically with fire blight resistance as a priority, which is a major reason they've become the standard for new plantings in disease-prone regions like ours.

If you're choosing rootstock for a new planting, fire blight resistance is worth weighing as heavily as mature tree size.