Etiology and distribution of foliar fungal diseases of citrus in Panama

Abstract

The etiology and distribution of foliar fungal diseases of citrus in Panama were studied in this work. In total, 85 orchards spanning six provinces were surveyed from 2011 to 2013. Symptoms observed ranged from yellow-brown spots on the abaxial surface of the leaves, brown lesions on petals, twig dieback as well as raised pustules on leaves and fruit. Representative fungal isolates obtained from symptomatic plant tissues were identified based on morphological characteristics, sequences of the ITS, EF1-α and TUB2 loci, and pathogenicity tests. Citrus greasy spot, caused by Zasmidium citri-griseum (=Mycosphaerella citri), was identified as the most prevalent fungal disease of citrus in Panama, confirmed in 68.2% of the orchards. Postbloom fruit drop (PFD) and Key lime anthracnose, caused by Colletotrichum acutatum sensulato, and melanose, caused by Diaporthe citri, were identified for the first time in Panama. Citrus scab, caused by Elsinoë fawcettii, was also detected. Greasy spot was found mainly in areas with a tropical monsoon climate (Am) and to a lesser extent in tropical savanna (Aw) and tropical rainforest (Af) climates. Melanose, PFD and citrus scab were detected only in areas with Am and Af climates. Information about the etiology and geographic distribution of fungal diseases in Panama will help to design effective strategies for disease management.