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Larry Sagers Horticultural Specialist Utah State University Extension Service Thanksgiving Point Office © All Rights Reserved
The following information is courtesy of Shawn Steffan, Utah State University Extension Service Integrated Pest Manager Technician
TREE FRUIT PEST ADVISORY UPDATE: May 14th, 2003
FIRE BLIGHT: Given the warmth of today and the forecast for the next several days, any wetting event in orchards with open blossoms will likely facilitate infection. The bacteria are present in high numbers in most orchards in Utah County, as well as an isolated orchard in Cache County. Yesterday's fire blight warning is still in effect for northern Utah.
Visit this website http://extension.usu.edu/ipm/FireBlightTables.htm for more information on the model outputs.
The prolonged bloom period and cool temperatures have obviously allowed the fire blight bacteria to proliferate. The programs attempt to "model" bacterial growth and include critical orchard events, but the output can be flawed because of the variability in the interaction of environmental conditions. For this reason, it has been advisable to treat apples and/or pears despite the recent low-to-medium risk estimates. When trees are in bloom for weeks, and the bacteria are present, bee foraging will quickly spread the bacteria throughout an orchard. Several cold, dry days can then "fool" the models into thinking the bacteria have declined, but a single warm day followed by rain can have significant consequences for trees with any open blossoms.
For more information on disease management in Utah tree fruit, visit http://www.extension.usu.edu/plantpath/fruit\_diseases/fruit\_diseases.htm . **********Insect Advisory***********
CODLING MOTH: continue to be caught in Box Elder, Davis, and Utah Counties. Reports also indicate that Salt Lake County and the colder parts of Cache County are catching substantial numbers of moths. Visit this weblink for newly updated information on codling moth development (as well as Peach Twig Borer and Western Cherry Fruit Fly), biofixes, and treatment intervals: http://extension.usu.edu/ipm/PhenolTables.htm.
Projected spray dates remain at late-May/early-June for all of northern Utah.
In various peach trees, many outbreaks of aphids have been controlled by the activities of predatory lady beetles and hover fly larvae. These beneficial insects can destroy local aphid populations when given the opportunity. Lady beetles are present in all monitored orchards at this time.