Date: Mon, 5 Jan 1998 15:01:38 -0500 (EST) From: Perry Malouf <pmalouf@access.digex.net> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg61$foo@default> Subject: phytotoxic styrofoam
Hello everyone,
I'd like to relate an interesting observation I made recently, which could be
very important for others in this forum. It concerns the phytotoxicity of
colored styrofoam peanuts, of the sort often used as cushioning material in
packaging.
In summary, I believe these colored pieces of styrofoam were responsible
for setting back several of my Nepenthes. Other growers should be careful.
Here are the observations.
I repotted several small plants about a year ago. I always put a shallow
layer of styrofoam peanuts in the bottom of my pots, followed by a clump of
potting media (sphagnum/perlite). Then I put the plant on top of the media,
spreading out the roots (old potting media is removed as much as possible).
Finally I drop in more media on top of the roots and lightly tap the pot down
on a table top a few times to settle the media around the roots.
Though the plants grew nicely after a month of adjustment, I recently noticed
that some of the plants were dying back. The lower leaves would turn
yellow and then dry up, followed by the upper leaves. (These plants were
about 7" in diameter and only 4" tall). The change was fairly sudden,
occurring over a period of 2 weeks. It was strange, especially after such a
healthy growth spurt.
This past weekend I repotted some of these plants. Invariably I noticed that
the unhealthy ones had roots growing _through_ a _colored_ styrofoam
peanut. Then I remembered one line in a posting by Al Bickell (when he
recited his recipe for Nepenthes potting media). He described how he puts
styrofoam peanuts in the bottom of his pots, and then added in parentheses
"white ones; colored ones are phytototoxic". [I'm paraphrasing here.]
Suddenly it all made sense. When the plants were enjoying a growth
spurt of green tissue, they were also growing more roots. The roots
finally came in contact with some colored styrofoam and grew through it.
At this point the roots began absorbing phytotoxic material and the
plants started to decline in health.
Since the rest of my plants are doing well, since I've not seen any sign of
other pathogens on the sick plants, and since all the plants experience the
same growing conditions, I surmise the colored styrofoam is the problem.
(The healthy plants I repotted hadn't yet grown roots into the colored
peanuts.) I'm going to repot all my plants over the next few weeks, and use
white styrofoam from now on.
By the way, I'm trying a different spin on my old recipe for potting media.
Instead of soaking the sphagnum in water, I'm soaking it in a 1:1 dilution of
peat tea. Let's see what happens.
Regards,
Perry Malouf
This archive was generated by hypermail 2b30 : Tue Jan 02 2001 - 17:31:28 PST