Hawthorn - Disease information and Management Recommendations. 
HOST PLANT DISEASE SYMPTOMS MANAGEMENT
Hawthorn Crataegus monogyna Rust, Gymnosporangium globosum and others Yellow/orange lesions form on leaf surface in early summer followed by tiny white tubes beneath. Infected fruits also have tiny white tubes. Twigs occasionally infected. Remove small brown to tan galls on the alternate host, red cedar (juniper), or the entire plant before spring. Remove visible infections on hawthorn before sporulation. Cockspur hawthorn, Crataegus crusgalli, is resistant.
CHEMICAL: Chlorothalonil, mancozeb, triadifmefon, or zyban AS PER LABEL DIRECTIONS.
These pages some times contain pesticide recommendations. Changes in pesticide regulations occur constantly, some materials mentioned may no longer be available, and some uses may no longer be legal. All pesticides distributed, sold, and/or applied in the USA must be registered with the appropriate State Department of Environmental Conservation (DEC). Questions concerning the legality and/or registration status for pesticide use in the USA should be directed to the appropriate State Cooperative Extension Specialist or your regional DEC office. 
READ THE LABEL BEFORE APPLYING ANY PESTICIDE.