See:
Pear (Pyrus spp.) - Fire Blight
Cause Erwinia amylovora, a bacterium that survives in affected wood of this and many other ornamentals. This is the same fire blight that attacks apple, pear, and other closely related plants. It usually goes unnoticed on ornamentals such as cotoneaster, hawthorn, and pyracantha.
Symptoms A necrotic blight of the flowers and rarely shoots. Blossom blight is usually inconspicuous and may easily go unnoticed. New shoots wilt in late spring. Affected shoots turn brown or black while leaves turn red-brown. Shoot tips curve back, giving the shepherd's crook appearance. Freshly blighted shoots may produce ooze drops on older wood later in the season.
Cultural control
- Prune out diseased branches; cut at least 6 inches below affected tissue.
- Plant resistant cultivars.
- Susceptible-P. angustifolia, P. koidzumii, and P. atalantioides.
- Moderately susceptible-P. crenulata.
- Moderately resistant-P. coccinea var. lalandii, P. fortuneana.
- Resistant-P. hybrids var. 'Mohave', 'Navaho', 'Shawnee', and 'Teton'.
Chemical control
- Dormant season for holdover cankers.
- Bonide Liquid Copper Fungicide at 0.5 to 2 fl oz/gal. H
- CuPRO 5000 at 1.5 to 5 lb/A but only up to 2 lb/A when new growth is present. Group M1 fungicide. 48-hr reentry.
- Nu-Cop 50 DF at 1 lb/100 gal water. Group M1 fungicide. 48-hr reentry.
- Prebloom and bloom period.
- Agri-Mycin at 100 ppm. Tolerant strains of the bacterium easily develop with repeated use of this product. Alternate with other bactericides to prevent or delay buildup of tolerant strains. Group 25 fungicide. O
- Arbor-OTC is registered for trunk injection, see label for details. Group 41 fungicide (antibiotic). 12-hr reentry.
- Badge X2 at 1.5 to 2 lb/A. Group M1 fungicide. 48-hr reentry. O
- Bonide Liquid Copper Fungicide at 0.5 to 2 fl oz/gal. H
- CuPRO 5000 at 1.5 to 5 lb/A but only up to 2 lb/A when new growth is present. Group M1 fungicide. 48-hr reentry.
- Ferti-lome Fire Blight Spray (streptomycin) at 1 Tbsp/2.5 gal water. H O
- FireWall 50 WP at 0.68 oz/25 gal water is registered for residential gardens. Group 25 fungicide. 12-hr reentry.
- Junction at 1.5 to 3.5 lb/A. Group M1 + M3 fungicide. 48-hr reentry.
- Monterey Liqui-Cop at 3 Tbsp/gal water. H
- Nu-Cop 50 DF at 1 lb/100 gal water. Group M1 fungicide. 48-hr reentry.
- Phyton 27 at 2 to 4 oz/10 gal water. Group M1 fungicide. 48-hr reentry.
Note: Aliette and Areca are registered but are not recommended because control is too variable and it is not compatible with copper products.
Reference Van Der Zwet, T., Orolaza-Halbrendt, N., and Zeller, W. 2012. Fire Blight: History, Biology, and Management. APS Press/American Phytopathological Society.