Question: Conifers and seasonal chloroses??

michael frankis michael.frankis at
Fri Nov 12 15:36:58 EST 1999

Is this something new, that has only recently started happening, or are you just
noticing for the first time something that has always happened?

Reason I ask, is that many conifers turn yellowish in winter, a character
usually cited as reducing the amount of chlorophyll so as to be able to cope
with extreme winter cold more successfully.  What I don't know is whether your
observations refer to this, or to something else new and potentially more
serious.  Please let me know.

In Scots Pine (Pinus sylvestris), this yellowing is variable with origin -
Siberian origins go the yellowest (to a drab mossy green), while Turkish origins
(var. hamata) hardly turn yellow at all (which is why they are preferred for
christmas trees in the USA).  One selected clone of Scots Pine (named as cv.
'Aurea') turns such a bright yellow in winter, it makes a good selling point for
garden use.

I'll try and dig out some references to it over the next few days.

Michael Frankis
Newcastle, England

Mike the Tree Doctor wrote:

> Folks:
> I have to pose a general question to any with experience in the matter of
> seasonal chloroses in conifers - principally hard pines.
> I have a situation in southern New England (Zone 4) where for multiple years
> now I have observed gradual yellowing of pitch pines (Pinus rigida), table
> mtn. pine (Pinus pungens), and to a lesser degree 'Waxman' eastern white
> pines as each winter approached.
> The trees in question are from multiple provenances, in multiple soils,
> obtained in multiple years. Not each individual of a species for lot is
> affected. I have done the usual battery of soil and paired soil/foliage
> nutrient assays - all are inconclusive. Soil pH, iron, manganese, copper,
> Ca:Mg ratios are all in the ball park, but micronutrient concentrations in
> foliage are off in some tests. All trees have been treated with NPK,
> sea-kelp extracts, humates, etc. at various times.
> Generally speaking, the condition goes away or attenuates greatly with the
> onset of Spring - any ideas or similar experiences.
> Thanks!
> --
> Mike the Tree Doctor

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