Your gut instinct was correct: Thousand cankers disease has not been detected in Michigan. It is not a valid reason to sell.

I appreciate your immediate response, I have a plantation of approx. 400 walnuts that are about 40 years in your opinion should I be concerned of these trees surviving another 25 or thirty years for future generation is this thousand cankers predicted to spread even though not detected yet in Mi. thanks for your help just trying to put this to rest. todd

I'm glad you took the time to reach out instead of just going with what the buyer told you. In terms of wood quality, this disease only affects the outer material, the bark, cambium, and maybe a bit into the sapwood. Even when heavily infested, the trees are still harvestable with minimal economic impact. In areas where the trees are not otherwise stressed, damage to native black walnut trees (if that is what you have planted) has not been extensive. There is no reason to recommend early harvesting.

Reliable information is available here:

https://thousandcankers.com/

Here is additional information about disease severity in neighboring Pennsylvania:

https://www.pa.gov/agencies/pda/plants-land-water/plant-industry/plant-protection/thousand-cankers-disease.html