Here in the North, Scale is a problem on a number of temperate woody plants.
You may also encounter scale sometimes on perennials and tropicals kept in containers,
Around here, a horticultural grade oil, sometimes in combination with an insecticide,
is applied via can sprayer, or a trigger sprayer. If you would want to use organic products,
combining Rotenone with the oil, or using Rotenone alone, I believe would work.
The oil obviously smothers the insects, and the insecticide, if any were used
in conjunction, would hasten their demise. I myself have not had any issues with
phytotoxic reactions, when
applying oil to exotic plants, for an insect control issuse.
There may be someone else in the forum, who is from a warmer climate, who
may have more info, regarding oil spraying treatment in warmer climate zones.
I have used this method before, on some larger Aroids, purchased from a wholesaler,
which had the critters on them, when they arrived at the greenhouse.
I have never treated the soil, in my experience, scale is almost always found up on the plants,
not at the ground.
What we also encounter up here, is that ants can be associated with the scale, and the ants
are drawn to the plants, because of the "honey dew", that the scale may produce.
Indeed, the largest scale we see here in Illinois, is the scale Neolecanium
which is usually only seen on Magnolias. It can get to be as large as, and looks
like a yogurt covered Almond!
I have to use a picture id to figure out which scale is which. An excellent reference book to use,
"Insects That Feed on Trees and Shrubs," from Cornell University Press.
This is a remarkable book, which has incredible photographs
of the many types of insects that can infest plants
across the United States.
I myself do not know of any book, that would deal with tropical scales,
if the scale infestation you have would not be a "local" scale.
I hope that this posting will be helpful to you.
Elgin, IL USDA Zone 5 B
From: Sherry Gates <TheTropix@msn.com>
To: AroidSendMessage <email@example.com>
Sent: Saturday, August 29, 2009 1:46:59 PM
Subject: [Aroid-l] scale insect
I have encountered a problem I haven't had to deal with.... SCALE insects. This past Spring, we moved from Beaumont, Tx (zone 9) to the Woodville, Tx area (zone 8), about 55 miles north. I've noticed on a couple of plants(Aroids) that scale are getting on them. Affected so far were Anthurium Big Bill and Monstera del (variegated). Just a couple have been slightly infested and I've immediately taken them to the bathtub and removed them by hand. What's the best way to kill them and prevent infestation
without harming my plants? I try so hard to use organic methods for insect control & fertilization, but I'm ready to break out the big guns on this, if necessary. I've never had this problem, so I'm kind of at a loss. What's safe for Aroids, but lethal to the little *%$!!!#$!? I'm keeping a sharp eye out for any of the obvious ones, but I'm guessing that I need to treat the soil as well. What's my best bet?
Thanks for any advice, Sherry Gates