MaryBlyt is predictive program for fire blight in apple and pear. It was developed by Paul Steiner and Gary Lightner at the University of Maryland, and has been proven to be effective in various regions of the US, including the Midwest. The system uses weather conditions and growth stage to predict likely incidences of four phases of fire blight.

• Date
• Phenological Bud Stage (PH): dormant, silver tip, green tip, first bloom, petal fall, tight cluster, pink, full bloom, secondary bloom
• Minimum (MIN) and Maximum (MAX) Temperature
• Wetness (WET): rain, dew, heavy fog, heavy spray
• Trauma (T): noted when a trauma event has occurred
• Spray (S): to denote when the orchard has been sprayed with an antibiotic