J
*Journeyman*
Just trying to understand...what are you talking about regarding leaf burning? Are you talking about blade teeth burning or more the inside of the leaf?Funny I always use cal mag from veg til week 6 in flower....I think the mag helps to reduce the burning of the leaves, and the cal to help twisting/turning of leaves... When I first started to see something I thought was a magnesium/calcium deficiency I began to run cal mag and have never had problems since...Mind you I never run it at full strength!
Ca must be supplied/available/utilized throughout the growth cycle. If you get behind you need to foliar feed cause only way you'll get it into Ca deficient older growth.
I'd bet money, and give odds, that most peeps dealing with PM have low Ca levels in their plants which in turn will give you lower sap pH levels. Ca inactivates the pectolytic enzymes produce by PM on contact. Just FYI Ca ions are more concentrated in the leaf tips