Agree with other posters, we need to know where this hose is located.
Also, it's not clear if the "hose in the picture" means the large one with the repair or the smaller one above it. I cannot see evidence of a leak from either hose, but we need to know what you do see.
Finally, are you certain the fluid is diesel?
Larry, Eileen, and Finley
2004 Alpine 36FDDS
Third motor home, first Alpine, no need for another.