Old Land Syndrom : informations ?

Larry Caldwell larryc at teleport.com
Sat Nov 15 00:35:45 EST 1997

In article <346BFF7B.689 at univ-savoie.fr>,
Francois PELLISSIER <pellissier at univ-savoie.fr> wrote:

> I visited recently plantations of Pinus patula in South Africa. These
> afforestations have been done on former agricultural lands. Curiously,
> if plantations on previous grass land are succesfull, those located on
> areas where soybean and maize were cultivated previously are
> unsuccesfull. Foresters looked after pesticides residues, nutrients
> deficiency, pathogens... but all seems OK. Because some weeds (Cyperus
> esculentus) develop very intensively on such lands, I suspect that they
> could release allelochemicals which could inhibit Pinus seedlings
> establishment.
> Do you know similar problems anywhere in the world.
> Do you have any informations which could help to solve this ?

Suppression of competing vegetation is always helpful. 

Were the pinus seedlings innoculated with mycorrhizal fungi before
planting?  I innoculated firs with various truffle sp. last winter.
I was doing a seedling survival inventory this week, and noted a much
darker color to the needles of the innoculated seedlings vs. seedlings
planted with no innoculation or even natural reprod.  Last summer was
a good summer for seedling survival, so I can't make any conclusions
about the contribution to seedling survival, but the innoculated trees
*appear* to be more robust.

Appropriate mycorrhizae for pinus in North America are various suillus
and boletus sp.  Some of them are excellent edibles, and form a very
profitable second crop in tree plantations.  There is evidence that
trees entertain a succession of mycorrhizae during their lifetime.
I'm sure a South African mycologist could suggest appropriate 
mycorrhizae for the climate and species.  

-- Larry

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