Prime under exterior caulk?

[tomtheelder2020]

Doing maintenance on my 70-yo v-groove shiplap siding. The boards are horizontal and have horizontal cracks at the board ends. Moisture has degraded the wood adjacent to the cracks. Where this is minor (say, 1/16 inch), I wire brush out the worst, then stabilize the sides with PC-petrifier, and caulk with DAP Alex Fast Dry (sand-able to an invisible repair). However, where wood degradation is worse, I cut a deep V-groove down to sound wood (usually not more than 1/4 inch wide at the surface. My question is this: for these deep grooves, do you think the caulk will adhere better to the bare (sound) wood or should I hit it with primer first?

Thanks for any insights. Also, If you have alternative approaches I am open to suggestion.

 

[Snoonyb]

The petrifier seals the wood, which may also affect the adhesive properties of the caulk, however if you are satisfied with the results, so far, just continue.Time will tell.