Is there a Doctor in the house?

[richinsd]

I wanted to share some pictures that I took right before pruning and see if anyone has similar patterns on their canes. What could cause these spots and what’s the remedy?

 

[BigDaveK]

Not an expert - looks fungal to me.
Resembles pictures of phomopsis viticola that I've seen. Don't know what to do about it, sorry.

 

[Daboyleroy]

https://ipm.ucanr.edu/agriculture/grape/phomopsis-cane-and-leafspot/

 

[richinsd]

Thanks for the pointer. This seems to describe it pretty well.

“Infected canes appear bleached during the dormant season. Severely affected canes or spurs exhibit an irregular dark brown to black discoloration intermixed with whitish bleached areas. The black specks visible in the bleached areas are pycnidia that develop during the dormant season.”

I just finished my dormant spray (sulfur lime oil) this weekend so hopefully that will help.

we did have a surprising amount of rain post bloom last year so maybe that enhanced the problem.

As far as treatment. I have been using captan (not enough last yea apparently). The UC article suggests mancozeb as a preferred fungicide but it says don’t apply it after bloom? What do you do if it rains after bloom?