Disease Note.

Yellow Leaf Blister Caused by Taphrina populina on Eastern Cot-tonwood in Mississippi. T. D. Leininger, Southern Hardwoods Laboratory, USDA Forest Service, Stoneville, Miss. 38776-0227 . S. C. Redlin, USDA-APHIS, Plant Protection and Quarantine, Riverdale, Md. 20737-1236 and T. E. Nebeker, Department of Entomology and Plant Pathology, Mississippi State University, Mississippi State 39762-9775. Plant Dis. 79:967. Accepted for publication 10 July 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0967A.

Yellow leaf blister, caused by Taphrina populina (Fr.:Fr.) Fr., was observed on 2-year-old and older eastern cottonwood (Populus deltoides J. Bartram ex Marsh.) trees in commercial plantations in Issaquena Co., near Filler, Miss. Symptoms were first observed in mid-March 1995, about 2 weeks after bud-break. The blisters, ranging from 1.5 to 15 mm in diameter, were initially bright yellow, changing to pale brown as the asci matured. Asci, typically lacking stalk cells, were 50 to 70 urn long x 18 to 22 μm wide and ascospores were hyaline and globose with diameters of 4 to 6 μm consistent with the description of T. populina (1). The occurrence of symptoms varied from one or two blisters per leaf to numerous blisters that coalesced to form irregularly shaped, thickened masses, resulting in leaf curling and deformity. Blisters typically developed on the abaxial leaf surfaces midway between the mid-rib and leaf margins and the average area affected on a diseased leaf was approximately 20%. Trees entering their second year had more blistered leaves than older trees. Disease incidence on individual 2-year-old trees varied from very slight to 50% of leaves infected and did not appear to be related to genotype. Taphrina populina has been reported on P. deltoides in Louisiana, Alabama, and South Carolina (1). This disease was not recorded in the 1964 Revised Index of Mississippi Plant Diseases, and has not been reported in Mississippi until the present. Yellow leaf blister is not considered economically important, which may explain why it previously has not been reported. The disease may have been favored by greater than normal rainfall and warmer high and low temperatures in March and April 1995. Voucher specimens have been deposited in the U.S. National Fungus Collections (BPI 802896) Beltsville, Md.