Thanks Jay. My knowledge of this
stuff is very limited but it did concern me once I began to read some
of the info on the internet. We see lots of poorly grown ornamental Anthurium
in some of our local stores, often showing signs of what may be
disease. I have a relative that is a district manager for a large
retailer and he says they throw away lots of plants as a result. I
just wouldn't want anyone to get the stuff in a prized collection.|
Thanks again for the info.
Jay Vannini wrote:
Anthurium blight has been with us forever and affects a wide range of
aroid genera. Breeders, including me, often select for plants that show
apparent tolerance to it but generally have learned to live with it
lurking in the wings. I am not sure that there are any Anthurium spp.
nor hybrids that are truly 100% blight-resistant, although the
riparians antioquiense and amnicola are known to transmit their
tolerance to andraeanum hybrid (the so-called andraecolas) offspring.
Conversely, there are a number of old andraeanum and crystallinum
hybrids and quite a few montane spp. that are exquisitely
susceptible to blight. Whether or not we are seeing more aggressive
strains emerging in the trade is another matter entirely; I have not
imported stock from the 'States since 2006 so would not be the right
individual to address this possibility. It would be interesting to hear
from Denis Rotolante, who would certainly know whether they are seeing
new antibiotic-resistant strains, and with whom I exchanged info on
Xanthomonas management in greenhouses in 2000-2001.
I completely disagree
with the notion that small scale growers cannot effectively
control this blight and should not be buying anthuriums now because of
it (!!!). While the last time I actually had a lab make a positive
pathogen determination for me was almost 10 years back, I think many of
us know it when we see it, and I certainly no longer have the dread
that I used to have for it when I first started growing anthurium in
the late 90s. I suffered a number of severe outbreaks stemming from
imported plants early in the last decade but, frankly, I have not had a
serious problem with it for years in spite of growing more than "just a
few" plants for cut flower ('Tropic Fire' and my own hoffmannii based
hybrids) and 0000s of foliage-type collector goodies.
Basically, what makes anthurium blight control especially difficult for
commercial growers is that the pathogen is rapidly spread, not only by
mechanical means such as non-disinfected cutting tools, employees'
hands, clothes, etc. - DR mentioned once that Cuban treefrogs
clambering from plant to plant in his greenhouses were a suspected
vector! - but also by splashing water and leaves banging against each
other (this is a bad thing generally for all anthuriums!). Anyone who
has this problem should be extremely careful to avoid "hard" overhead
watering or exposure to rain. While this seems counterintuitive to a
tropical aroid fan, bestest and fastest control is gained when foliage
is kept dry, well-ventilated but nearly motionless in order to minimize
mechanical damage to the leaves that facilitates entry for the bacteria.
- My frontline treatment for foliar infection is Agrimycin
(streptomycin sulfate 17%) AFTER removing all visibly infected plant
tissue to a point well beyond the classic yellow halo line
circumscribing necrotic tissue. I would need to check my notes to see
at what concentrations I usually apply, but I do seem to recall that I
make three apps about 5-8 days apart. I often rotate or follow-up with
copper-based ag-chem although it is contra-indicated in the
literature...some have recommended systemic copper but I have found it
unnecessary, expensive and quite phytotoxic.
- While I occasionally use concentrated quat ammonium dips for
disinfecting my pruners (at least three in the greenhouse, used in
rotation), I definitely favor flaming tools between cuts to all
my plants to red hot. If you do not consistently disinfect tools
between plants, IMO, you will never gain good blight control once it is
firmly established in your collection.
- It is VERY important to remove infected leaves once they are visibly
blighted to avoid the blight becoming systemic. I will say that my
experience has been that if one permits a severe blight to extend from
the lamina down the petiole (which will often mush at the geniculum and
the base) to the main stem, the plant is generally going to hand in its
lunch pail in very short order. If this occurs, toss these critters
- It seems that many growers-gardeners love to fondle their plants when
they're in their grow spaces. I cannot emphasize enough that any
handling of aroids that are known or suspected of being blighted should
be kept to an absolute minimum, and hands disinfected between this kind
Note: IME, Agrimycin will invariably burn/disfigure leaves of Anthurium
veitchii and its hybrids, usually quite severely, as well as some old
andraeanum primary hybrids and few others. It can also be extremely
hard on seedlings.
Date: Mon, 11 Jan 2010 13:54:00 -0600
Subject: [Aroid-l] Anthurium blight
A warning from our friend Leland
Miyano from information originating from botanist David Scherberich.
There is now a very bad Anthurium blight
which may be spreading. At least two gardens in France have had to
deal with this one which has no cure. The one that is really bad is Xanthomonas
campestris pv. dieffenbachiae which causes the leaf margins
to turn yellow and all the leaves to drop. I would suggest you be very
careful about buying new Anthurium right now! This has the
potential to kill an entire collection.
Some species appear resistant but others spread it quickly. Some
commercial growers in Hawaii lost almost entire crops of ornamental Anthurium
(the kind you buy in the store) so be very careful about buying any Anthurium
in a local nursery or discount store!
Any of you that are knowledgeable about this blight please pass along
what you know.
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