Brown spot disease caused by Alternaria alternata (Fr.: Fr.) Keissl is a serious problem forproduction of tangerines and tangerine hybrids in Iran. The Tangerine pathotype causes brownspot disease on young leaves and immature fruits of limited varieties of mandarins and tangerines(Citrus. reticulata Blanco). Specificity in the interaction between tangerine and the pathogen isdetermined by a hos...