[permaculture] [Fwd: Re: [SANET-MG] Late Blight]
Lawrence F. London, Jr.
lflj at intrex.net
Sun Jul 26 19:42:16 EDT 2009
-------- Original Message --------
Subject: Re: [SANET-MG] Late Blight
Date: Sat, 25 Jul 2009 22:16:38 -0500
From: Douglas Hinds <cedecor at GMX.NET>
Reply-To: Sustainable Agriculture Network Discussion Group <SANET-MG at LISTS.IFAS.UFL.EDU>, Douglas Hinds
<cedecor at GMX.NET>
Organization: CeDeCoR, A.C.
To: SANET-MG at LISTS.IFAS.UFL.EDU
The causative pathogen of late blight isn't a virus.
Late blight is a fungal diease.
Phytophthora infestans is an oomycete or water mold that causes
the serious potato disease known as late blight or potato blight.
Late blight (Phytophthora infestans) is a fungal disease that
attacks the leaves, stems, and tubers of potato plants. In the
1840s, P. infestans caused the Irish potato famine, when a million
people starved and another million and a half emigrated out of
The latter information source mentions a number of measures found to
I myself found a reference stating that the beneficial fungus
Pisolithus tinctorius produced substances with antibiotic activity
against Phytophthora some years back. Pisolithus tinctorius has been
used as an inoculant (although usually for trees) so the possibility
of developing a biocontrol method based on competition from
beneficial fungi deserves further study.
If Late Bight is caused by Phytophthora infestans and Phytophthora
infestans is an oomycete or water mold, and Oomycetes as members of
the chromistans, which in turn, are part of the larger Kingdom
Protoctista, then Phytophthora infestans is neither a fungi nor an
algae (although algae are Protoctistas). In any case, it's far from
being a virus.
Personally, I subscribe to the taxonomy Lynn Margulis postulates,
which recognizes 5 Kingdoms, with Fungi and Protoctista along side
Plants, Animals and Bacteria.
My main point was that the causes of Late Blight can be understood
and dealt with appropriately, if the will to invest in research is
there. (As things stand, most research is motivated by the desire to
develop products with commercial potential. This is unfortunate
because Agriculture is for farmers and comsumers rather than
chemical pedlars, IMO. IOW, Agriculture is an activity dependant on
naturally ocurring biolological processes and should be understood
and dealt with as such).
Pythium oligandrum is an Oomycete. IT IS A PARASITE OF MANY FUNGI
AND OTHER OOMYCETES INCLUDING Botrytis, Fusarium and PHYTOPHTHORA.
IT HAS BEEN LICENSED AS A BIOCONTROL AGENT IN THE FORM OF AN
OOSPORE SOIL TREATMENT, which reduces pathogen load and
concomitant plant disease.
P. OLIGANDRUM CAN GROW WITHIN THE ROOTS OF CERTAIN PLANTS,
including TOMATO and sugar beet. Production of auxin-like
substances stimulate plant growth. Defense responses can be
induced in the plant, which primes the plant from further
infection by pathogenic fungi, oomycetes or bacteria.
Tomatoes and Potatoes are related of course, which suggests the
potential for innoculating potao seed with Pythium o. &/or treating
the soil in which potatoes are planted with it.
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