26-04-2003, 12:26 PM
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How to visually distinguish Potassium and Mag deficiencies?
(David D.) wrote:
(...)
Both affect older leaves. Both cause marked interveinal chloriosis
with reduced new growth. I know that in some cases, Potassium
deficiencies cause corrugation deformities in new growth as well (e.g.
passionfruit), but not always. I also read that Potassium shows marked
scorching on the leaf edges, but again, not always, and indeed,
pictures of Magnesium deficiencies in some crops also show necroses in
affected leaves. The one symptom (and its a judgement call rather than
an absolute, which isn't really helpful) that Potassium has in
contrast to Magnesium deficiency, is that affected leaves are dropped
more reluctantly with the former than in the latter.
(...)
If you weren't certain it was a deficiency of one of those nutrients,
I would suspect nutrient leaching from excess flow through irrigation.
General chlorosis is one easily recognizable symptom of poor nutrition
that can occur in some substrates even when feeding regularly.
If you are monitoring tissue analysis for hydroponic growth,
adjusting pH to match known natural substrates of the plant would be a
first step, IMO. After that I would check the tissue analysis for
possible interference with take-up of one of the major nutrients(and
availability of sulphur and possibly calcium depending on the native
substrate information). After that I would adjust minor elements based
on information from the tissue burns.
If it is a field crop, I know nothing.....except that organic
fertilizers and ground rock have often been highly recommended in this
newsgroup g
Dennis
Dennis
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