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  Scale on Anthuriums
From: Adam Black epiphyte1 at earthlink.net> on 2002.05.16 at 20:47:37(8821)
A day after discussing with my wife how we have been lucky to have never
had any serious problems with pests in our ever-growing collection of
plants, I found leaf scale all over one of my Anthurium clairnervium.
These things must multiply exponentially in a short period of time, as I
figured I would have noticed them before it became as bad as it is
currently.They are all over the plant's leaves and petioles. I consider
myself lucky in that the affected plant is on my desk at work, 18 miles
away from my home and greenhouse containing all my more treasued Aroids.
Until now, I have never needed to treat plants with insecticide, and I
was curious what other list members would recommend for sucessful
treatment of scale on an Anthurium.

Aside from what insecticides work best, I would be curious to know if
different species of leaf scale are host specific to the genera of
plants they feed on.. I ask because up until now 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.

Thanks for any replies on solutions to this probem. I am thankful that
the affected plant is isolated from my main collection, and I can't
imagine what it would be like to have a problem like this spread in my
greenhouse. I am definately going to get more serious with putting new
aquisitions in quarantine prior to mixing them with my other valuables.

Adam Black

From: "Michael Pascall" mickpascall at hotmail.com> on 2002.05.17 at 08:21:54(8823)
Adam , rather than use a toxic chemical for scale , I have been using
detergent with a few drops of ammonia added , this really works . For the
very small hard scale we get on bromeliads a second spray with a 'organic'
canola white oil spray really finishes them of.

Michael Pascall,

From: mburack at mindspring.com> on 2002.05.17 at 08:23:26(8824)
I constantly deal with scale and aphids on everything as we have a nonstop ant problem in Florida... and if you have a lot of ants here.. you have a lot of scale and such.

What you experienced with the plant not infecting others is common... I beleive (from much experience) that many of these things will stay very "local" on a single plant until they are forced to venture elsewhere.

For example I have a gigantic Acalphia hispida plant growing dead center in my landscaping. It is the most pest prone plant I have ever seen next to some gingers.... The plant can be covered from top to bottom with scale, aphids, mealybugs(God forbid!) and yet the surrounding plants are clean.

From: Dan Levin levin at pixar.com> on 2002.05.17 at 19:00:26(8827)
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!

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