Hot water bath treatment for
mites
Why should you bother? If you think this is a bother,
don't do it. However if you have just a few plants and do not
want to invest in expensive chemicals, or are chemically
sensitive… you might want to try this "organic approach. One
potential added advantage to this approach is that it is
possible that it may kill both eggs and live mites at the same
time…. So it MIGHT be a one shot treatment. Also, one of the
problems with the chemical approach is that it is easy to miss
just a few mites… that is why it is so important to treat
three times. But with a hot water bath, you should get them
all in one shot.
In the end, I can make no guarantee since I have not
had mites and not used this method to cure them. All I can
tell you that based upon research I have read it SHOULD work
and based upon my own experiments it SHOULD not kill your
plant. This is posted for informational purposes only and
claims no expertise and guarantees neither efficacy or plant
safety.
How long do you need to
soak?
What temperature is required?
As with so many other things in
life, different people say different things. I have seen
references to 15 minutes at 110 and 30 minutes at
100 degrees. Unfortunately it is very hard to have an
entirely stable temperature for so long. Therefore I suggest a
combined technique. Starting at 112 degrees --- ending at 110
degrees--- for 30 minutes. This should mostly meet either
requirement.
Does it work (kill mites)?
The following link is just one reputable site where
this technique is mentioned:
http://www.greenhouse.cornell.edu/pestsdis/pdfs/Guidelines2004/04Bio&MgtArthro.pdf.
Is it safe for my Violets?
I was wondering
this. I tested this on a disposable noid violet I had. And the
plant survived fine with no apparent damage
How do you do it
How do you do it?
I will now describe a
technique that I think will work based upon my own
testing.
If you want to do this, you
need to understand a few background principles that are
important for proper technique.
Thermal Mass: A larger mass of water will resist
cooling better than a smaller mass of water. When you add a
room temperature plant to a heated water bath, the bath will
lose temperature as it gives up heat to heat up the plant.
Therefore it is important to start with a heat bath
temperature a little above target range. I use 115 degrees as
an initial temperature
Convective heat loss:
It is important to insulate the heat
bath container to eliminate convective heat loss
Evaporative heat loss:
it is important to cover a hot water
bath to prevent evaporative cooling
Test your technique first: As with everything else in life,
you will get better with practice. Therefore I suggest that
you practice this technique on plants you do not value before
trying it on your best plants. You might even want to buy a
couple of cheap noids at the local home depot to practice on.
Where are the mites:
As I understand it, mites live in your
foliage and perhaps on top of the soil, but not in the root
mass. Therefore I invert the plant into the water bath (upside
down) with some of the root ball ok to remain outside the
bath.
Constructing an insulated
hot bath container:
You need a container that will
keep your hot water bath at a relatively constant temperature
for about 30 minutes. Here is one way. Get a cheap Styrofoam
picnic cooler.
Partially full it with
shipping peanuts.
Inside the cooler, have a pot, a mixing bowl, or
something similar nested into the shipping peanuts. The bowl
should be able to hold about gallon of water so it
will have sufficient thermal mass. The bowl should have some
top/lid (improvised is ok)
The water: If you have ever had a pet with fleas, you may know
that you can throw a flea into water and it will happily float
for a very long time. However if you put just a touch of
detergent in the water, the flea sinks to the bottom and
drowns. I have no idea if the same principle applies to spider
mites…. But I figure it cannot hurt to add just a drop of
detergent, insecticidal soap, or physan 20 to the water to
make this treatment even more effective. But remember--- more
is not better- you just need a tiny amount.
How do you get the correct water temperature
bath?
·
Heat up a
large quantity of water in a pot on your stove. This water
should be about 130-140 degrees.
·
Have a
separate container of cool water.
·
Pour the hot
water into your insulated container.
·
Cover the
container with out the plant in it.
·
After 2
minutes, measure the temperature. It will have dropped a
little from the temperature of the water in the pot.
·
Now you start
lowering the bath temperature slowly to your target temp (115)
by slowly adding cool water and measuring the
temperature.
·
If you happen
to go below target temperature, just add more hot water.
·
If you have
too much water, use a cup and remove some water
·
The bowl
should be about ¾ full before you add the plant. The extra
room in the container is required to accommodate the increased
water level after
you add the plant.
·
When you reach
the correct target temperature (115), invert the plant into
the water bath bowl.
·
Cover bowl
immediately
·
Cover bowl
cover with a towel inside the cooler
·
Put cover on
the picnic cooler
·
Set timer for
30 minutes
·
After 30
minutes, remove the plant and plunge the plant into a luke
warm water bath (75-80) which will remove residual heat from
the plant.
·
As the plant is soaking in warm water bath,
measure the final temp of the heat bath to verify that it is
100 degrees or
over.
If you follow these
instructions, the initial bath temperature will be 115, this
will fall to 110-112 when you add the plant, after 30 minutes,
the bath will be about 102.
I have tested the above and it
has worked for me without hurting the plant. Of course I
cannot guarantee your results. Again I would encourage you to
try this with a disposable plant before using on anything
special. Also, it would not hurt to save a leaf or two "just
in case"
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