The sad news was posted to the Roses forum:

kohala said: Just wanted to let the forum members know that my husband Dennis, "Kohala" on the forum, passed away last Saturday. He so much enjoyed the Rose Forum, learned so much and had such a great time raising his roses and taking pictures and sharing them. I really appreciate all the joy you all gave him (particularly when you solved a problem he was having or gave him a 'thumbs up' for his pictures)
Mahalo Nui Loa,
Donna Brown (Mrs. Kohala)

My sincerest condolences to the family and friends of Kohala/Dennis. May he rest in peace in heaven's most beautiful garden. 🌴🌹🌸🌺🌿

My deepest sympathy to you and your family and friends. I'm so sorry.

Very sad to see that NGA has lost another member.
My condolences to his family and friends, and wishes for many happy memories of Dennis.

Sympathy to the family of Dennis, fair winds.

Sending our condolences.

Sending my sincere condolences Donna for the loss of your husband, may the memories of Dennis bring comfort and peace to your family and friends. He'll be missed here.