Hi Jack,
" How do you tell which deficiency symptoms are linked to which nutrient "
You refer to a book like the book titled "Nutrient Deficiences in Bedding Plants" that I quoted from above. The deficiency symptoms are different for each nutrient element. I quoted the book on Boron above. For Magnesium in the Zinnia chapter it says,
"The initial symptom of magnesium deficiency is an interveinal chlorosis of the lower leaves (A). Initial plant growth (bud size, leaf color, and petal expansion) of deficient plants is equal to the control, but as symptoms progress, growth is inhibited (B). As interveinal chlorosis symptoms advance, marginal necrosis also develops on the lower leaves (C). As before, the capital letters in parenthesis refer to photographic illustrations tagged with those letters.
As a general principle, elements that are readily translocated in the plant have deficiency symptoms on the lower older leaves, while elements that are not readily translocated in the plant have deficiency symptoms on the upper newer leaves and buds. In other words, if it can, a plant will "steal" a needed nutrient from older parts to use in newer growing parts.
I purchased the book,
Nutrient Deficiencies in Bedding Plants from Amazon in January 2009. It was published by Ball Publishing copyright 2007. Apparently it is now out of print, because the current asking prices are outrageous. The official price of the book was $69.95 U.S. or $87.95 CAN. The Amazon price I paid was $48.97 plus $3.57 tax. Amazon typically sells books for less than the publisher price. However, Amazon now lets third party sellers sell through them, and as you can see they frequently ask for highly inflated prices.
https://www.amazon.com/s/ref=n...
You might be able to find the book in a library. Or find another book that covers the same subject. Or find Internet websites that document nutrient deficiency symptoms.
After you have studied the subject, you can just look at a zinnia plant and recognize what nutrient it is deficient in.
ZM (not associated with any product or vendor mentioned or linked)
