Re: [aroid-l] Amorph Blues

From: Dan Levin <levin at pixar.com> on 2004.07.04 at 09:38:40(11711) Neil- I knew exactly what pest you'd found even before I clicked on the link to view your image. Sadly, I find these all too often in the rotting tubers/ corms of many aroids; Amorphophallus and Alocasia especially. The pest you discovered is the larval or maggot stage of (enter sinister organ music...) the ubiquitous Fungus Gnat. Thing is- and this is important- it is my firm belief based upon years of rotting more aroid tubers/ corms than I'd ever admit to in a public forum, that these fungus gnat larvae are more akin to a nasty secondary infection and are rarely if ever the primary causal agent. +More Not to diminish their impact; I'm sure the larvae -greatly- accelerate the demise of any tuber/ corm they infect, but there always seems to have been an initial case of rot or decay in said plant parts which has preceded the invasion. Even if it's only a matter of hours or one day... i.e. I've never observed fungus gnat larvae laying siege to a healthy tuber- though they are reputed to eat root parts and consequently stunt plant growth. Once fungus gnat larvae are discovered inside a tuber or corm, the problem is most certainly compound and not quite as simple as "eliminate the pest and all will be well... " You will have some fungal or bacterial rot to contend with and by implication, sour compost or media. If you google "fungus gnat" you'll find pages & pages of info; most Universities with an Ag school offer info on this pest & potential controls. A few such sites hosted here in the states: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7448.html (UC Davis) http://www.ipm.ucdavis.edu/PMG/B/I-DP-BRAD-LV.004.html (a Larvae image) http://ohioline.osu.edu/hyg-fact/2000/2114.html (Ohio State) http://insects.tamu.edu/extension/bulletins/uc/uc-028.html (Texas A&M) My advice for hatching Wilbert's micro mail-order Amorpho tubercles: - Never overpot, stick to a suitably sized container - Keep moist but never wet, unless growing in very high heat in a media/ pot with great drainage and much air movement - Check/ lift the little tikes every other day; scrupulously check for rot or desiccation... it's a fine line! Checking them daily is not too often. - If you have fungus gnats in your growing area, by all means: drench the soil in all of your pots with an appropriate insecticide on a preventative basis. By the time your application needs to be curative, you're too late. I'd be happy to offer info/ personal data on effective pesticidal chemistries, but will refrain from doing so unless asked. Hope this is of some help, I wish for you much success. -Dan Neil Gordon wrote: > So i broke it in half and what was inside? One of these little buggers. > http://www.ng23.abelgratis.co.uk/bug/damn_bug.jpg > It was (past tense intended!) about 5mm long. > > Does anyone recognise what it may be? Is it contagious? Should I spray > the soil of my other amorphs with insecticide? >

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