What incisions?The strength is the same for a particular species whether it is treated or untreated, depending on the incisions treated wood may not be as strong as untreated. Surface incisions will have little effect, deeper incisions may weaken the material.
For the same exact species, there is no difference in strength. "Treating", as in pressure treating is primarily intended to protect lumber from insect and fungus infestation. That does very little to cope with weather conditions. Since it's done to softwoods (dimensional lumber) the actual weight may depend on how wet, or the type of chemical used.A treated 2/4 weighs much more than a standard untreated 2/4. Does treating do anything for strength or is it purely weather protection?
I always though of treated wood was more heavy duty/strong but maybe it a false sense.