Hi! First off I would like help identifying what kind of grape vine this is if anyone has any idea. I am located in Vancouver BC. Secondly I am trying to figure out the deficiencies in this plant. In previous years, I have had issues with powdery mildew but I do not see any signs of it this year. I first assumed that this was a general nitrogen deficiency but after fertilizing with a 20% N-P-K for a couple weeks, I have seen minimal change. I am going to continue fertilizing but my fertilizer does not have Magnesium in it so I am going to start treating with dolomite lime. The only problem is, if this is an iron deficiency the lime will raise the ph thus limiting Fe absorption. The yellow patches are the main concern and more pronounce on older leaves which leads me to believe it is a problem with mobile nutrients (i.e. not iron which is immobile but maybe magnesium which is mobile). But, the newer leaves are also quite yellow, but more uniformly yellow. I have noticed that the chlorosis is mostly interveinal and much more prevalent on areas that are in direct sunlight. Any help is greatly appreciated, please let me know if I have made any mistakes in my analysis. Pics: imgur.com/a/gcyHq Thanks, Steve
Grapes look pretty healthy. One thing I did notice is that the first grape buds that popped out are much more densely packed than the ones that developed later. I have concluded (whether right or wrong) that this is a result of iron deficiency. I don't think I have alkaline soil so there simply must not be enough iron so I am going to apply some iron chelate to the soil.
