Can citrus trees get fireblight?
I have a disease rapidly moving through my mandarin/rangpur lime trees. Trees are in pots. Problem began about 2 months after I moved them indoors (I live in north Washington state). Leaves wilt and turn grayish brown. They do not get brittle until a few days after they turn completely brown. Problem started with outer leaves and progresses toward the trunk. Some branches have green leaves. I have photos. Trees were repotted into larger containers about seven months ago. I let them dry thoroughly before watering. Fertilizing seems to have accelerated the spread of the disease. Trees are under grow lights with about 12 hours of light per day. Photos of fireblight seem to most closely resemble the problem.
No citrus don't get fire-blight. There are other plant diseases possible, but from the photos and your description, I suspect it is a water related disorder and not a plant disease.
"I let them dry thoroughly before watering." You may be letting them get too dry between waterings. How do you measure this?
I use multiple methods of assessment for when to water, physical and intuitive: finger probe of soil surface to maybe 1 inch. Soil moisture meter to 10". Visual appearance of foliage for possible wilting, and when wilting gets extreme there is a color change to a lighter green and then possible bluish-green color, which is usually past the point of no return. I also try to "tune in" to the plant needs, if you will, and let it tell me when it needs water.