Effects of Fosetyl-Al, Metalaxyl, and Enterobacter aerogenes on Crown and Root Rot of Apple Trees Caused by Phytophthora cactorum in British Columbia. R. S. Utkhede, Agriculture Canada, Research Station, Summerland, British Columbia V0H 1Z0 Canada. E. M. Smith, Agriculture Canada, Research Station, Summerland, British Columbia V0H 1Z0 Canada. Plant Dis. 75:406-409. Accepted for publication 18 October 1990. Copyright 1991 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-75-0406.

Fosetyl-Al applied as a foliar spray and a drench, metalaxyl as a granular broadcast and drench, and Enterobacter aerogenes as a drench were evaluated for 3 yr at three sites for control of crown and root rot, caused by Phytophthora cactorum, in naturally infected apple trees. All chemical and biological treatments reduced crown and root rot disease ratings of apple trees. This indicates that these treatments have the ability to arrest further symptom development in naturally infected trees if they are treated as soon as symptoms appear. Fosetyl-Al as a drench and metalaxyl as granular broadcast significantly reduced death of trees infected with crown and root rot in orchard 1. Fosetyl-Al applied as a foliar spray, metalaxyl as a granular broadcast or drench, and E. aerogenes (strain B8) as drench applications significantly increased fruit yield and reduced crown and root rot disease ratings. The biological treatment with E. aerogenes has as much ability as chemical treatments to control crown and root rot of apple trees.