How to add potassium

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Coriba

Junior
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I’ve planted 25 merlot vines on 3303 rootstock. My soil is clay rich derived from glacial till. It is pretty rocky. I live on central Vancouver island. I haven’t done a soil test, I will, but published soil surveys indicate that the pH is around 4.5 to 5 and that it has a low cation exchange capacity. This our second year and we have noticed some of the leaves turning red. Most likely potassium deficiency or red blotch, hopefully potassium deficiency. Pictures below. I understand that grapes are heavy potassium users and that suggests it needs to be supplemented as part of crop management. I also understand that potassium is not very mobile in clayey soils.

My question, how do I get potassium to the roots of my vines? I’ve read a heavy application of potassium surface, or drip irrigation with soluble potassium surface. What is the easiest method and does it work?

Two of our vines have grapes, tiny little clusters.
 

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Thank you, that is a good link.

These are Merlot grapes and I’ve seen the reddish leaves on several plants and usually one or two leaves each plant.

This is not a grape growing region, there are a few vineyards around but not many. It is difficult to find the right fertilizers from suppliers that service vegetable greenhouses and cannabis operations. Lots of those around here. I can get water soluble KSO4 (0, 0, 53) or granular KCl (0, 0, 62), I’m not sure what they have. Also difficult to find the right fungicides as I’m not registered as a farm. I’m trying to make due with what I can get.

Thanks for your help.
 
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I talked to a wine maker who said he uses foliar sprays to apply potassium. I had never heard of such a thing, but if true, it might get you buy until you can get potassium built up in the soil.

H
 
Thanks all, I’ve found a source locally on the island. I’ve read from UC Davis that foliar application has little impact, I will try it anyway.
 
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