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Fire Blight: There is still little risk of fire blight infections right now, despite the rain, because the temperatures are cool. As long as they remain cool there is little if any risk of fire blight infection. If temperatures get warmer, pears and susceptible apple varieties will be at risk. Homeowners can use sprays of copper or of Fertilome fire blight spray. It contains the antibiotic, streptomycin. The trees are at greatest risk when they are in bloom. Fire blight sprays can be safely applied to blooming trees because they are antibacterial, not insecticidal. Therefore they can be safely used and will not kill the bees. Never spray blooming trees with an insecticide when they are in bloom. Needless to say you should not be sprinkling fruit trees while they are in bloom for several reasons. 1. They do not need the water right now. 2. The bees will not work the trees if they are being sprinkled so you will not get good pollination. 3. Keeping the trees wet by sprinkling increases their susceptibility to diseases. Apple Scab: Weather data from the USU Kaysville station suggest that we had condition favorable to apple scab infection on last Saturday (4-27-02). Growers in the Northern Wasatch Front Region with a history of apple scab may want to spray to control apple scab if you did not have a protective chemical on the trees. This is seldom a problem for homeowner trees. Some powdery mildew controls will offer some protection for apple scab. Insects: Codling moths are expected to emerge by 200 DD. Most sites along the Wasatch Front have reached 200 DD (See DD table at http://extension.usu.edu/ipm/advindd.htm), so they are expected once we have evening temperatures above 60F. Note that this is emergence and not the spray time. Sprays are generally applied about three weeks after full bloom. Be on the look out for aphids, European red mites, leafrollers and fruit worms. Western cherry fruit fly will not start to attack cherry is until sometime in June. Spraying before that time is a waste of the product and an unnecessary pollution of the environment.
