Mandarin Fruit Rot Caused by Alternaria alternata and Associated Mycotoxins

Mandarin (Citrus reticulata) fruits naturally infected by Alternaria alternata had two different symptoms: black and gray heart rot. Two samples of the black rot contained, respectively, tenuazonic acid at 21.0 and 87.2 mg/kg, alternariol monomethyl ether at 0.5 and 1.4 mg/kg, and alternariol at 1.0 and 5.2 mg/kg, whereas one sample of gray rot contained only tenuazonic acid at 173.9 mg/kg. The causal agents isolated from the two types of heart rot differed in toxin production, colony morphology, and pathogenicity to lemon and orange fruit.