First Report of Diplodia mutila on Golden-chain Tree (Laburnum x watereri). . T. J. Proffer, Kent State University, Salem Campus, 2491 St. Rt. 45 South, Salem, OH 44460. Plant Dis. 80:1303. Accepted Tor publication 10 September 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-1303B.
Golden-chain tree (Laburnum x watereri (Kirchner) Dippel) cv. Vossii is a small ornamental tree valued for its long, pendulous racemes of yellow flowers. In 1995, twig and branch dieback and stem cankers were observed on a golden-chain tree located on the Salem campus of Kent State University. Externally, the affected branches exhibited either a yellow discoloration or a blackening of the normally green bark. Consistent with canker diseases, the internal cortical and cambial tissues were discolored and necrotic. Four fungi associated with twig dieback and branch cankers were identified from fruiting bodies on the branches and fungal isolates recovered from the necrotic tissues. Three species of fungi, Fusarium lateritium Nees:Fr, Nectria cinnabarina (Tode:Fr.) Fr. and its anamorph Tubercularia vulgaris Tode:Fr, and Cytospora leucosperma (Pers.:Fr.) Fr., were associated with the yellow cankered tissues. Diplodia mutila (Fr.:Fr.) Mont, was associated with the black cankers. While F. lateritium has been previously reported from cankers on common golden-chain tree (L. anagyroides Medik., which is one of parental lines of this hybrid), this is the first known report of N. cinnabarina, D. mutila, and C. leucosperma from a species of Laburnum in the United States. In 1996, 65 2-year-old seedlings of L anagyroides were wound-flap inoculated with mycelium from either F. lateritium, N. cinnabarina, C. leucosperma, D. mutila, or a sterile control. F. lateritium and D. mutila produced disease symptoms similar to the respective naturally occurring cankers and were successfully reisolated from necrotic tissues. The isolates of N. cinnabarina and C. leucosperma did not cause cankers, suggesting they were secondary organisms and not responsible for the observed symptoms. The control inoculations did not cause cankers. This report adds D. mutila to the pathogen list for golden-chain tree.