Hi,
    Thanks for contacting the Master Gardeners. Sorry to hear about your dogwood. Thank you for the picture also, that is helpful. I did some research about dogwood diseases and none seem resemble your picture. I am sending a link of common diseases found on dogwoods. What is mostly resembles is leaf scorch. it has been a really hot summer and I am wondering if it receives enough water to compensate for water needs in high heat. This could lead to the browning of the leaf tips that you are seeing.
    You may need to increase water to your dogwood to prevent further browning. Cooler temps will also help. The leaves do look a little droopy, making me suspect that this  might be the case. I am also sending you a couple of links about leaf scorch from our CSU information. I hope you find this helpful. Contact us if you have any further questions.Thanks, Jeanine

Dogwood Diseases:
https://hgic.clemson.edu/factsheet/dogwood-diseases-insect-pests/

Leaf Scorch:
https://extension.colostate.edu/topic-areas/yard-garden/leaf-scorch-2-911/

https://planttalk.colostate.edu/topics/insects-diseases/1400-12-leaf-scorch-trees-shrubs/