Abstract: A movable heat applicator is provided that is configured to treat a citrus tree for a bacterial disease. The heat applicator includes a heat containment structure that at least partially enclose a citrus tree. A steam generator adapted to produce steam is provided to release steam at a desired pressure and temperature for treating the citrus tree. A steam dispenser is connected to the steam generator and may be arranged in the interior of the heat containment structure at a positioned to dispense steam below branches of the citrus tree. The steam is dispensed into the heat containment structure to create a steam heated treatment environment to treat the bacterial disease. The movable heat applicator may also include a chassis coupled with the heat containment structure and a drivetrain that supports the chassis over a ground surface for moving the containment structure.