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Re: Scale on Anthuriums

  • Subject: Re: Scale on Anthuriums
  • From: Dan Levin <levin@pixar.com>
  • Date: Fri, 17 May 2002 21:00:26 -0500 (CDT)

Adam Black wrote:

> ... I had a small
> Philodendron williamsii sitting right next to the affected Anthurium,
> with leaves touching. I searched the entire plant over, and could not
> find one scale on the Philodendron. Nothing on any of my other aroids
> and non-aroids in the office either.


Be careful here- were you searching only for the distinctive adult "scale"
insects on your office plants, or were you on the lookout for the juvenile
"crawler" stages as well?  The crawlers are much harder to spot, as they
tend to appear as small to very small non-descript translucent little blobs.
And the little creeps can hide rather well, too.  If you don't find any adults
on your other plants within 4 weeks or so, then the buggers may have stayed
put on your Anthurium.  In my experience scale is a very eclectic pest with
regard to host plants.  The only common thread I've ever noticed- infested
plants are almost always stressed in some manner; with a reminder that being
in need of repotting or being root bound is often times a stress qualifier.

Scale does indeed spread very rapidly- it's always seemed to me the horticultural
analog of aquarium "ich" (Ichthyophthirius multifiliis, a protozoan parasite of
FW tropical fish).  The similarities are: once you've discovered an infestation by
the presence of those adult stages, you're already too late.  In both cases the more
readily visible adults are next to impossible to kill due to an outer "shell" they've
developed for protection; both adult phases are largely fixed in place upon their host
and ironically, about to die.  But not before producing many 100's of babies per
organism underneath that outer shell (so you're correct in noting that populations
can increase exponentially!).  And as with "ich", scale is most vulnerable and best
controlled while in the juvenile (crawler) stage.

They're susceptible to virtually anything then, from most classes of insecticides to
Michael Pascall's kinder, gentler recipes.  The trick here is timing, as reapplications
are required with each successive brood cycle.  Here's what I'd suggest based on
recent experience (a friend gave me a cycad which I put straight into my collection
without looking... 1 month later... doh!!):

Spray or even soak ALL of your office plants in a solution of Insecticidal Soap.  This
will stop the current crawler stages.  Next, treat with a long lasting systemic insecticide.
The very best one being "Merit" (Imidacloprid).  Merit is odorless, can be effectively
applied as a soil only drench (you don't have to spray) and though it takes a few weeks
to translocate into your plants, residual control is at least 1 month and often longer.
Happy hunting!

 -Dan Levin

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