Factors Associated with the Decline of Sweet Cherry Trees in Michigan: Nematodes, Bacterial Canker, Nutrition, Soil pH, and Winter Injury. H. Melakeberhan, Visiting Assistant Professor, Department of Entomology, Michigan State University, East Lansing 48824. A. L. Jones, P. Sobiczewski, and G. W. Bird. Professor, Department of Botany and Plant Pathology and Pesticide Research Center, Michigan State University, East Lansing 48824; Visiting Scientist, Institute of Pomology and Floriculture, 96-100 Skierniewice, Poland; and Professor, Department of Entomology, Michigan State University, East Lansing 48824. Plant Dis. 77:266-271. Accepted for publication 26 October 1992. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1993. DOI: 10.1094/PD-77-0266.

Some of the biotic and abiotic factors associated with the decline and death of sweet cherry (Prunus avium) trees in Michigan were studied. In a survey of 26 orchards in the summer of 1990, nematodes belonging to Pratylenchus, Criconemella, Xiphinema, Meloidogyne, and Pratylenchus spp. were detected in samples from 24, 11, 15, 17, and 17 orchards, respectively. Pratylenchus penetrans was the most abundant nematode in these orchards. However, populations of all nematodes from healthy and declining trees were not significantly different. Pseudomonas syringae pv. syringae and P. s. morsprunorum were isolated from leaves or branches collected from trees in each orchard. Detailed studies of five 6- to 16-yr-old orchards in 1990 and 1991 indicated that low soil pH, some nutritional disorders, and winter injury were among the abiotic factors associated with tree decline. Soil pH, which appeared to increase available aluminum, was as much as 2.5 units below the recommended level. Leaves from most orchards had insufficient levels of Ca and N. Leaf Al concentrations of 110–392 µg/g were detected in three orchards. Severe winter injury was observed in one orchard. Although several biotic and abiotic factors appeared to result in the decline of sweet cherry trees in Michigan, only one or two factors were associated with decline in individual orchards.