The use of Temperature Threshold Treatments in the Control of Fireblight on Pyrus Kawakami
Pamela M. Elam and Keith Holmes
Abstract: Ornamental pears are extensively planted within the urban forest. In many climate zones, they become heavily infected with the bacterial disease, fireblight (Erwinia amylovora), which causes severe branch dieback and can kill young trees. This disease is also very serious in nursery stock, and trees are no longer grown in some areas. The objective of this study was to evaluate the usefulness of a temperature treatment threshold used in commercial pear production and to compare copper, streptomycin and aluminum tris for use in the prevention of fireblight on 5 gallon nursery stock of Pyrus kawakami. The temperature treatmect threshold is based on daily mean temperatures. In this study, it was found that the best preventative material was copper, followed by aluminum tris. All three compounds provided high degree of control. The daily mean temperature treatment threshold for commercial pear production appears to be later than would be appropriate for nursery production.