Answer: Smoke bush is deciduous so it will lose its leaves this fall; be patient for it to releaf next spring, these tend to leaf out relatively late.
You would not apply dormant oil routinely to all shrubs and trees, no. Please check with your local county extension to see if they have any recommendations for preventive applications for any of the specific plants you are growing (for example, certain fruit trees may be given annual routine sprays), or to determine if any of your plants had a particular problem that could be treated using oil. If so, they will be able to tell you what to use and how/when to apply it for the best results. In many cases the timing depends on the weather each year and dormant oil is usually applied in late winter when the plants are in fact dormant.
Fertilizer is best applied only if a need is indicated for it by soil tests. The tests would give you specific recommendations as to what is needed. Your county extension should be able to help you with the testing and interpreting the results based on what you are growing.
It is actually better to underfertilize than to overfertilize. If you have mature trees and shrubs, or your trees and shrubs are surroudned by or adjacent to a lawn that is fertilized, you probably do not need to fertilize them at all. Using a year round layer of organic mulch several inches thick will help feed the soil gradually as it breaks down over time. This mimics nature's processes and should be sufficient.
If your plants are new and/or your soil is infertile, you might as a rule of thumb apply a topdressing of good quality compost and/or a general purpose granular fertilizer such as 10-10-10 according to the label instructions. This is usually done in the spring.
Evergreens would not be fertilized in the fall. Deciduous plants are sometimes fertilized in the fall after they have begun to go dormant and drop their leaves. If you did this type of split application, you would use a half a year's amount in fall and half in the spring. Do not fertilize now as this could encourage late season growth that would not have time to harden off before winter and thus result in excess winter damage -- it is still too early for a fall application.
I hope this helps.
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