What grows on live tree leaves?

dwheeler at teleport.com dwheeler at teleport.com
Fri Sep 19 11:02:14 EST 1997

In article <IKsH00O5IgXV091yn at teleport.com>,
  larryc at teleport.com (Larry Caldwell) wrote:
> In article <874219375.22787 at dejanews.com>, dwheeler at teleport.com wrote:
> > It is probably too late to do anything about the fungus this year.
> > However, adjustaing any nearby sprinklers to spray at lower levels may
> > aid next year's foliage without applying fungicides, which can kill the
> > mycorrhizal fungi necessary for the tree's health, and thus should be
> > avoided.
> A spray of wettable sulfur can be used to control powdery mildew without
> harming mycorrhizal fungi.  Just use enough to wet the leaves, not so much
> as to water the whole blinking tree!
> This can also be used on shrubs and vegetables.  Sulfur is harmless to
> insects and a natural soil nutrient.  I don't know if it's approved for
> organic use, but just wash it off the surface of vegetables and it
> won't hurt you.
> During the dormant season, a dormant spray of lime-sulfur solution and
> light oil is used to control many tree diseases.  Once again, as long as
> it isn't over-applied, it won't hurt mycorrhizae at all.
> -- Larry

I have strong reservations about applying sulphur to plants. Sulphur plus
water equals some very plant unfriendly stuff, and I'd require some
documented proof.

Even if sulphur doesn't affect mycorrhizae, it could affect endophytic
fungi. These fungi may kill one or two cells on the leaf surface, but
produce mycotoxins which evolve and change very rapidly. This is the
trees natural defense mechanism against insect pests, and may explain why
trees with non- natural acidic rainfall are not doing well world-wide.

Daniel B. Wheeler

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