Question: Conifers and seasonal chloroses??

truffler1635 at truffler1635 at
Fri Nov 12 13:05:30 EST 1999

In article <FL37vp.L38.A.ebony at>,
  kbonnici at wrote:
> I would assume that its ordinary seasonal leaf drop. However, you say its not
> happening to all individiauls in a species, so that seems puzzling--unless
> within species needles are dropped not every season, but every other, or every
> third season. Chlorosis is certainly not seasonal, and you likely would have
> discovered that with your nutrient assays and pH testing.
> HTH,
> Kellie
This is just a guess, Mike and Kellie. Seasonal chlorosis could be an
indication of stress from lack of mycorrhizae. It's possible that acid
rain could be affecting (just a little bit) the pH of soils, which can
eliminate mycorrhizae (which are very susceptible to changes in soil

You note that some trees are not affected, Mike. I'm guessing that these
trees have already developed appropriate mycorrhizae to supply the trees
with the appropriate nutrients. Some of these mycorrhizae leach
nutrients from bedrock, such as potassium, phosphorus, iron, other trace
metals; and are associated with nitrogen-fixing bacteria. Without
knowing what fungi are associated with which trees, it's impossible to
say anything further. But a suggestion may improve things: take a little
soil from the non-affected trees and mix into the soil next to the
affected trees. There is a good chance that essential mycorrhizae could
be spread that way.

Your question about the seasonal chlorosis could be that one or more
ectomycorrhizal fungi are going dormant, and therefore not gathering
nutrients for their host trees at that point. This most frequently
happens during the fall or winter, and is reversed during the spring
when ectomycorrhizae typically begin aggressively growing again.

Recently on the web I found a site that indicated at last 7 species of
mycorrhizal fungi could be found on a single half-centimeter of rootlet.
How many ectomycorrhizal fungi are necessary for tree health probably
varies from site to site. It's possible that treating with an
ectomycorrhizal innoculant would solve the problem.

Daniel B. Wheeler
> In article <nGKW3.4525$7m.262305 at>, "Mike the Tree Doctor" <mlamana at> writes:
> >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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