Re: Rosemary disease -a funereal lamentation


In light of the information at this site:
http://helios.bto.ed.ac.uk/bto/microbes/crown.htm  I would certainly recommend
looking into the biological controls you mention. BTW, thank you for bringing
this up. I have long been fascinated with the interaction between plants and
soil life, and that site above appears to have a wealth of information. I might
not have located it without the your post.

Regards, Ryan
Oxnard Plain (SoCal) 34.5N

"Vinciguerra, Alessandra" wrote:

> Dear Medit-gardeners,
> Some time ago I wrote about the mysterious disease that was slowly killing
> my rosemary hedge. I had samples of the infected plants analyzed at the
> local Plants Pathology Agency, and the sad response is that my plants are
> infected by a bacterium, the Agrobacterium tumefaciens. This  is commonly
> known as the crown gall agent. The damned microscopic  organism  apparently
> is able to  transfer part of its  DNA to the (unwilling) guest plant, and
> its DNA integrates into the plant's genome, causing the production of tumors
> and associated changes in plant metabolism. I think I described in the past
> the horrible tumors that were disfiguring my plants. These abnormal  growths
> interfere with the sap flow, and all parts above them just die.  By the way,
> the peculiar  mode of action of A. tumefaciens has enabled this bacterium to
> be used as a tool to genetically modify plants. Any desired genes, such as
> herbicide-resistance genes, but also new (non-plant) genes , can be
> engineered into the bacterial DNA and thereby inserted into the plant
> genome.  When I learned this I immediately thought of  the dreadful, and
> much discussed, strawberries with an anchovy genes,  perhaps a metropolitan
> legend, and other science-fiction monsters that were brought to our
> attention during recent OGM debates. Just imagine what a snake I was
> nurturing in my rosemary's bosom.
> There is no effective treatment for this disease, the only known successful
> one is a preventive biological treatment, which is basically a
> counter-active bacterium that you treat cuttings or young (i.e.not infected)
> plants with. Unfortunately the related commercial products are NOT available
> in Italy (Galltroll, Nogall, Diegall and such), I will have to order them
> abroad (also have to check if  it is legal to use them here).  Spraying with
> copper mixtures such as Bordeaux (copper sulphate and lime) can help but
> doesn't guarantee.
> What the Agency recommended is to remove all diseased and nearby plants (the
> bloody bacterium actually lives in the soils and spreads from that), burn
> them all, incorporate calcium dust in the soil, let it stay for a couple of
> months, then, if  I really want to, (!!!), replant new healthy plants and
> spray  with copper; besides preventively, methodically  spraying all other
> plants in the area. This is for my soft, non spraying, alternative methods
> approach to gardening. The real thing of course  would be to grow some
> disease resistant plants , or just grass, for about three years, to make
> sure that the monster disappears from the soil.
> I am desperate. My rosemary hedge is (as of tomorrow morning, was) 100 m
> long, a lovely, though casual, mix of Jessup's upright, and plain
> officinalis,  with  two shades of blue in the flowers. It is in bloom right
> now, still a beauty in spite of the gaps, and dying plants.  It was a very
> important  feature in the garden, dividing the orchard and vegetable area
> (with a certain formal pattern) from the main , informally arranged area. It
> was beautiful. This message actually has no other point than to  mourn my
> rosemary hedge.
> Thank you for the attention,
> Alessandra
>
> Alessandra Vinciguerra
> Superintendent of the Gardens
> American Academy in Rome
> Via Masina,5
> 00183 Roma Italy
> Tel. 39-6-5846444
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