Systemic downy mildew

[dwhill40]

Greetings,
Third year in a row specific vines get hit hard with downy mildew. Same vines, no difference in the surroundings, ground is clean, the downy seems to radiate from one area. Other vines of the same variety and more susceptible varieties remain clean. I use copper sparingly and do two dormant spray. I keep up with spraying and rotating different fungicides. Anyone have experience with eradicating what appears to be a locked in systemic downy mildew problem?

 

[VinesnBines]

Is the problem area more shaded or less morning sun? It could be the spores are overwintering. What variety? What fungicides are you using? Also where are you located?

 

[wood1954]

Have you tried phostrol or tebuconazole? They both work really well, phostrol can burn the plants if you use too much as I found out.
are you spraying your plant to the point of runoff?