Apple and pear growers should be ready to protect against fire blight. Many orchards in Berrien County were totally destroyed by an epidemic in 2000. Anytime after the start of bloom, a tree can get fire blight. Since we are in bloom in both pears and apples, now is the time to be ready for control. In order for the bacteria to get into the plant, it needs some form of an opening. Blossoms provide that opening. Plus blossoms have a sugary nectar that is an excellent food source for the bacteria. Thus, bloom-time is when the trees are most susceptible.

Fire blight needs several things to happen in order for an actual infection to occur. First, a susceptible host like apple or pears in bloom is needed. Second, a source of the bacteria needs to be present. After the last several years, most orchards have plenty of old fire blight cankers that can act as a source. Finally, you need the proper weather conditions. Warm temperatures with rainfall, dew, or high humidity are all needed for an infection.

Right now, in Southwest Michigan, not everything is present. Our cooler than normal temperatures have a low population of bacteria out there. In addition, the weather forecast for the next week is cooler, near-normal temperatures. However, if warm temperatures and rain occurs, it could start an infection. Bill Shane, district fruit agent maintains a daily update recording during the blossom season at 944-1477 ext. 805.

The best defense is to apply preventative sprays of streptomycin and Mycoshield just before a rain. Ideally one should not use more than 4 streptomycin sprays in a season to help avoid resistance. Three sprays during the bloom period and one spray for later if hail occurs. At least three are usually needed during bloom because with streptomycin sprays, only open flowers are protected. As new flowers open, they need new coverage. Remember, you need to control fire blight before it strikes.