First Report of Graphiola Leaf Spot Caused by Graphiola phoenicis on Date Palm (Phoenix dactylifera) in the State of Pernambuco, in the Northeast of Brazil. M. F. Lima, Agricultural Research Center for the Semi-Arid Tropics/Brazilian Bureau for Agricultural and Ranching Research (CPATSA/EMBRAPA), C. Postal 23, 56300-000 Petrolina-PE, Brazil. Plant Dis. 80:823. Accepted for publication 18 April 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0823C.
Date palm was introduced from Africa and the United States to the semiarid irrigated region of Pernambuco, Brazil (9° S and 40° W), in an attempt to diversify agriculture. The palm species has become well established in the semiarid environment. Graphiola leaf spot or false smut caused by Graphiola phoenicis (Moug.) Poit. was identified on 18 (5- to 10-year-old) date palm cultivars at CPATSA, in San Francisco Valley, Pernambuco. The fungus develops fruiting structures subepidermally on both sides of the pinnae and on the rachis. These sori are black (1 to 3 mm in diameter) and consist of two layers: the outer peridium is hard, dark, and persistent; the inner peridium is hyaline, membranous, and degenerates after the spore mature. Spores are produced inside the sori and they are interspersed with groups of sterile hyphae. The fungus and its development (2) as well as its taxonomic position as a smut fungus (1), have been described previously. For the last 7-year (1988 to 1995) period during which date palm has been cultivated at CPATSA the annual relative humidity ranged from 41 to 77%; the maximum and the minimum average temperatures were always between 35 and 23°C, favoring the development of the disease on palm. Severe infections can reduce tree growth and fruit production through premature death of the leaf tissues. The dissemination of the fungus among plants is favored by high plant densities (4x5 m), as opposed to low planting densities (8 x 8 or 10 x 10 m) in two of the five plots. Management practices include pruning and removal of the infected leaves to decrease the inoculum.References: (1) G. T. Cole. Mycologia 75:93, 1983. (2) E. Fisher. Bot Zeit. 41:745, 1883.