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Biological Control of Septoria Leaf Spot Disease of Hybrid Poplar in the Field

July 2003 , Volume 87 , Number  7
Pages  809 - 813

Laszlo Gyenis , Department of Agronomy and Plant Genetics , and Neil A. Anderson , Department of Plant Pathology, University of Minnesota, St. Paul 55108 ; and Michael E. Ostry , USDA Forest Service, North Central Research Station, St. Paul, MN 55108



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Accepted for publication 1 February 2003.
ABSTRACT

Biological control of Septoria leaf spot of hybrid poplars was investigated using disease-suppressive Streptomyces strains. Field experiments were conducted in 1998 and 1999 on potted trees placed in a hybrid poplar plantation near Rosemount, MN, and on field-planted trees in 1998 at St. Paul. At both locations, one resistant and three susceptible hybrid poplar clones were sprayed with Streptomyces spore suspensions and exposed to natural field inoculum of Septoria musiva. In the 1998 potted-tree experiment, strains GS-93-3, 93, and Mycostop in Tergitol or Triton X-100 solutions applied every 7 days significantly reduced leaf disease by 29 to 83% compared with the controls. In the 1999 potted-tree experiment, Streptomyces strain mixtures in Tergitol solution applied every 5 days significantly reduced leaf disease by 50 to 87% compared with the controls. In the 1998 plantation experiment, strains GS-93-3, 93, or Mycostop in Tergitol solution applied weekly, bi-monthly, or monthly significantly reduced leaf disease in all treatments by 64 to 78% compared with the controls.


Additional keywords: gram-positive bacteria, Mycosphaerella populorum, Populus spp.

© 2003 The American Phytopathological Society