Fireblight on Pear Trees

Seasonal gardening tips for June:

Plant Care

• Feed camellias, azaleas, and rhododendrons with an acid plant food.
• Remove dead flowers and mulch to keep the soil cool.
• Plant fresh herbs from young plants—basil, rosemary, thyme, mint, and sage are good options.
• Check roses for black spots on the leaves and treat immediately to prevent defoliation.
• Hydrangeas produce giant pink or blue flowers and will brighten shade gardens all summer.
• Meyer lemons are attractive, easy to grow, and have sweet-scented blossoms; plant one in a container to move it to a protected spot in winter.

Fire Blight on Pear Trees

Fire blight is a destructive disease common on pear, Asian pear, quince, and sometimes apple trees. It also affects pyracantha, cotoneaster, hawthorn, and related trees and shrubs. The disease can destroy limbs or even entire trees if left unchecked.

Symptoms

• Light ooze from cankers on branches, twigs, or trunks that darkens after exposure to air.
• Flowers, shoots, and young fruit shrivel and blacken.
• Dead, blackened leaves and fruit give the tree a scorched appearance.

The infection usually enters through flowers and moves down branches, infecting fruit, leaves, and stems. Warm, moist spring weather and rain during blooming create ideal conditions for the disease.

Treatment and Prevention

• Prune infected branches at least 8 inches below visible damage, often requiring removal of a larger branch.
• Dip pruning tools in 70% isopropyl alcohol or a 10% bleach solution (1 part bleach to 9 parts water) between cuts.
• Wash and oil shears after use.
• Dispose of all infected plant material.
• Next winter, apply copper sprays before bud break or streptomycin (an antibiotic) from bloom through petal fall at 4-day intervals (do not apply streptomycin when temperatures are below 65°F).
• Use low-nitrogen fertilizers on susceptible trees to avoid excessive new growth.
• Clean up around trees in fall, removing dead twigs and mummified fruit from the ground.