[Aroid-l] Anthurium blight

From: ExoticRainforest <Steve at ExoticRainforest.com> on 2010.01.15 at 19:35:09 Thanks Jay.  My knowledge of thisstuff is very limited but it did concern me once I began to read someof the info on the internet.  We see lots of poorly grown ornamental Anthuriumin some of our local stores, often showing signs of what may bedisease.  I have a relative that is a district manager for a largeretailer and he says they throw away lots of plants as a result.  Ijust wouldn't want anyone to get the stuff in a prized collection. Thanks again for the info. Steve www.ExoticRainforest.com Jay Vannini wrote: Steve:   Anthurium blight has been with us forever and affects a wide range ofaroid genera. Breeders, including me, often select for plants that showapparent tolerance to it but generally have learned to live with itlurking in the wings. I am not sure that there are any Anthurium spp.nor hybrids that are truly 100% blight-resistant, although theriparians antioquiense and amnicola are known to transmit theirtolerance to andraeanum hybrid (the so-called andraecolas) offspring.Conversely, there are a number of old andraeanum and crystallinumhybrids and quite a few montane spp. that are exquisitelysusceptible to blight. Whether or not we are seeing more aggressivestrains emerging in the trade is another matter entirely; I have notimported stock from the 'States since 2006 so would not be the rightindividual to address this possibility. It would be interesting to hearfrom Denis Rotolante, who would certainly know whether they are seeingnew antibiotic-resistant strains, and with whom I exchanged info onXanthomonas management in greenhouses in 2000-2001.   I completely disagreewith the notion that small scale growers cannot effectivelycontrol this blight and should not be buying anthuriums now because ofit (!!!). While the last time I actually had a lab make a positivepathogen determination for me was almost 10 years back, I think many ofus know it when we see it, and I certainly no longer have the dreadthat I used to have for it when I first started growing anthurium inthe late 90s. I suffered a number of severe outbreaks stemming fromimported plants early in the last decade but, frankly, I have not had aserious problem with it for years in spite of growing more than "just afew" plants for cut flower ('Tropic Fire' and my own hoffmannii basedhybrids) and 0000s of foliage-type collector goodies.   Basically, what makes anthurium blight control especially difficult forcommercial growers is that the pathogen is rapidly spread, not only bymechanical means such as non-disinfected cutting tools, employees'hands, clothes, etc. - DR mentioned once that Cuban treefrogsclambering from plant to plant in his greenhouses were a suspectedvector! -  but also by splashing water and leaves banging against eachother (this is a bad thing generally for all anthuriums!). Anyone whohas this problem should be extremely careful to avoid "hard" overheadwatering or exposure to rain. While this seems counterintuitive to atropical aroid fan, bestest and fastest control is gained when foliageis kept dry, well-ventilated but nearly motionless in order to minimizemechanical 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 planttissue to a point well beyond the classic yellow halo linecircumscribing necrotic tissue. I would need to check my notes to seeat what concentrations I usually apply, but I do seem to recall that Imake three apps about 5-8 days apart. I often rotate or follow-up withcopper-based ag-chem although it is contra-indicated in theliterature...some have recommended systemic copper but I have found itunnecessary, expensive and quite phytotoxic.   - While I occasionally use concentrated quat ammonium dips fordisinfecting my pruners (at least three in the greenhouse, used inrotation), I definitely favor flaming tools between cuts to allmy plants to red hot. If you do not consistently disinfect toolsbetween plants, IMO, you will never gain good blight control once it isfirmly established in your collection.    - It is VERY important to remove infected leaves once they are visiblyblighted to avoid the blight becoming systemic. I will say that myexperience has been that if one permits a severe blight to extend fromthe lamina down the petiole (which will often mush at the geniculum andthe base) to the main stem, the plant is generally going to hand in itslunch pail in very short order. If this occurs, toss these crittersasap.   - It seems that many growers-gardeners love to fondle their plants whenthey're in their grow spaces. I cannot emphasize enough that anyhandling of aroids that are known or suspected of being blighted shouldbe kept to an absolute minimum, and hands disinfected between this kindof manipulation.   Note: IME, Agrimycin will invariably burn/disfigure leaves of Anthuriumveitchii and its hybrids, usually quite severely, as well as some oldandraeanum primary hybrids and few others. It can also be extremelyhard on seedlings.   J     Date: Mon, 11 Jan 2010 13:54:00 -0600 From: Steve@exoticrainforest.com To: aroid-l@gizmoworks.com Subject: [Aroid-l] Anthurium blight A warning from our friend LelandMiyano from information originating from botanist David Scherberich. There is now a very bad Anthurium blightwhich may be spreading.  At least two gardens in France have had todeal with this one which has no cure.  The one that is really bad is Xanthomonascampestris pv. dieffenbachiae which causes the leaf marginsto turn yellow and all the leaves to drop.  I would suggest you be verycareful about buying new Anthurium right now!  This has thepotential to kill an entire collection.  Some species appear resistant but others spread it quickly.  Somecommercial growers in Hawaii lost almost entire crops of ornamental Anthurium(the kind you buy in the store) so be very careful about buying any Anthuriumin a local nursery or discount store! http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1392979/ Any of you that are knowledgeable about this blight please pass alongwhat you know. Steve www.ExoticRainforest.com Windows Live: Friends get your Flickr, Yelp, and Digg updates whenthey e-mail you. _______________________________________________Aroid-L mailing listAroid-L@www.gizmoworks.comhttp://www.gizmoworks.com/mailman/listinfo/aroid-l --------------070701030808030801010305

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