The development of fire blight on pears is nearly the same as that described earlier on apples, although pears appear to be more susceptible. This is because pears tend to have more flowers per spur than apples, and these flowers tend to remain open and susceptible for a longer period than those on apple. For example, individual apple flowers stay open for about 80 degree days DD above 40 F 44 DD above 4 C, while pear flowers stay open for an average of 120 DD above 40 F 67 DD above 4 C. Because of this longer flower life, nearly 90 percent of the total flower buds are open at full bloom on pears compared with only 65 to 70 percent of those on apples.

Address: PO Box 6108, Morgantown, WV 26506-6010
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Website: http://www.caf.wvu.edu/kearneysville/disease_descriptions/ompearfb.html