Rosemary disease -a funereal lamentation

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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