Testing of Cherry Rootstocks for Resistance to Infection by Species of Armillaria. T. J. Proffer, Department of Botany and Plant Pathology and Pesticide Research Center, Michigan State University, East Lansing 48824-1312. A. L. Jones, and R. L. Perry. Department of Botany and Plant Pathology and Pesticide Research Center, and Department of Horticulture, Michigan State University, East Lansing 48824-1312. Plant Dis. 72:488-490. Accepted for publication 7 January 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0488.

Ungrafted mahaleb, mazzard, and 17 hybrid Prunus rootstocks were inoculated with two intersterile groups of Armillaria and the incidence of infection evaluated after 27 mo. None of the interspecific Prunus hybrids was immune or highly resistant to infection. Mazzard, M × M 60, and GI 195-1 had the lowest—and mahaleb, Colt, M × M 2, GM 9, and GI 196-4 the highest—incidences of infection. Isolates of the four intersterile groups of Armillaria recovered from cherry in Michigan were used to inoculate 1-yr-old Montmorency sour cherry trees grafted on mahaleb and mazzard rootstock. On the basis of the number of grafted trees killed, mazzard was more resistant than mahaleb to infection. The higher resistance of mazzard to Armillaria in both experiments was consistent with field observations and supports the use of mazzard rather than mahaleb rootstocks in programs for the control of Armillaria root rot of cherry.