Asked April 08, 2021, 11:45 AM EDT
Hennepin County Minnesota
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Apple scab is common in Minnesota, so chances are, the pathogen spores are around your garden every year. However, some years apple scab infection on the trees is worse than others. If we are having a dry summer, we will see very little apple scab infection. In a wet year, we experience more apple scab. Last year for instance, the summer was very dry and we had minimal to no apple scab in Minnesota orchards. This year is predicted to also be drier than normal in Minnesota. You should also know that a little bit of apple scab on a tree is not devastating. You will still get a good crop even if a little bit of apple scab is present. However, large infections can definitely lead to a lot of inedible and disappointing fruit.
Resistant variety does not mean that it will never get apple scab. It only means that it is less likely to get apple scab than other varieties.
Armed with all this information, it is up to you whether or not to continue to spray for apple scab every spring. It is present in the environment, but won't cause infections on the trees every year. This year has a lower risk of apple scab than others, if dry weather predictions turn out to be true. If it is important to you that you do everything you can to eliminate the chance of apple scab, then continue having them spray annually. If you are ok with a little bit of scab, and want to reduce chemical inputs, you could consider telling them not to spray if the season is predicted to be very dry.
Hope this helps.
Glad to be of assistance.