permaculture

[Thomas Paul Jahn <thomaspauljahn@gmail.com>]

I can already see the problem. Plants are smart and will not keep up with
the systemic acquired resistance just because of the presence of a single
protein of a pest. If they wouldn't mind to keep the resistance constantly
on, they would do anyway. But they don't.
In the natural situation, the pathway will be switched on in part because
of harpin. And if the response as a whole is successful, the pathogen will
eventually vanish.
But when you keep applying the protein, eventually the plants will turn off
their signal perception and consequently their resistance in spite of the
presence of the protein. Then, when the real pathogen comes along, this
particular protein may not serve as a signal any longer, because the plants
are desensitized.

In the end, the protein didn't help the plant to develop resistance, but
prevents it from doing so.

I think the question is not, if Harpin is allowed in organic farming. The
question is, if it makes sense. And it does not in my eyes.
Companion planting and all the other good permaculture practices must be
the solution.


2011/11/25 Lawrence F. London, Jr. <venaurafarm@bellsouth.net>

> -------- Original Message --------
> Subject: [SANET-MG] is Harpin allowed in organic crops?
> Date: Thu, 24 Nov 2011 22:59:39 -0500
> From: jcummins <jcummins@UWO.CA>
> Reply-To: Sustainable Agriculture Network Discussion Group
> <SANET-MG@LISTS.IFAS.UFL.EDU>, jcummins <jcummins@UWO.CA>
> To: SANET-MG@LISTS.IFAS.UFL.EDU
>
> Harpin (MESSENGER®)
> In nature, Harpin is produced by Erwinia amylovora, a bacterium that
> causes the disease fire blight in apples and pears. A weakened strain of
> Escherichia coli was modified to produce Harpin on a commercial scale.
> Commercially produced Harpin protein is identical to the protein that
> occurs in nature. E. coli K-12 is considered to be a non-pathogenic,
> nutritionally deficient bacterium which is unable to grow in the
> environment. Harpin is concentrated from the growth medium of the
> genetically modified E. coli, and the bacterial cells are killed and
> removed from the marketed product.
> Harpin does not act directly on the disease organism, nor does it alter
> the DNA of treated plants, but instead activates a natural defense
> mechanism in the host plant, referred to as systemic acquired resistance
> (SAR). This new active ingredient is currently the only broad-spectrum,
> proteinaceous elicitor of SAR commercially available. Harpin is
> effective against certain viral diseases for which there are no other
> controls or resistant plant varieties. It also protects against
> soil-borne pathogens and pests, such as certain nematodes and fungal
> diseases, which have few effective controls except for methyl bromide,
> which has adverse human health and environmental impacts.
> The harpin gene has been used to produce GM rapeseed,
> cotton,chrysanthemum and rice.However, these crops are in an early stage
> of development.
> I wonder if Harpin can be used in organic production?
>
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