That is good. Fire blight is a bacterial disease which is difficult to manage. A common problem observed in trees in New Mexico each spring is blackening of leaves of pear, cottonwood, and many other trees. This can be due to slight frost damage or by wind damage. Young leaves in the spring are often very tender and subject to damage from the winds which develop during our warm desert days.
Temperatures can rise from very pleasant temperatures to rather warm mid-day temperatures.
These warm days following cool nights, when combined with our frequent spring winds, can cause rapid desiccation of the leaves. The leaf margin is the most likely injured part of the leaf. This desiccation can occur even if the soil has adequate moisture because the wind can draw water from the leaves faster than the tree can move it from the soil into the leaves. Very young trees may not exhibit symptoms because they are smaller and closer to the ground and more protected from the wind, and also because they have less distance to move water through the plant to resupply the leaves. Newly transplanted trees, with limited root systems, and those which have just begun rapid growth after a couple of years establishment following transplanting may be the most likely to show the symptoms.