August 15, 2015

Aphids / Duckweed

Today's Pond Q&A

In this issue:

- Bugs on Water Lettuce

- Duckweed as a Natural Control for Hyacinths


Question #1>

Hi Carolyn,

I have beautiful water lettuce. All of a sudden they started getting
these tiny black bugs on them. You have to look real close to see
they are a tiny bug of some sort. They are slowly destroying them.

Is there anything I can do to save them? They are just covered with
them. I tried washing them off so the fish would eat them, but I'm
sure they will be back.

Any suggestions, I don't want to lose them all. Thanks again.


Answer #1>


Those are aphids. I hate them and they can really make the plants
look ugly, but washing them off or removing by hand is one way to
handle them. Or you can remove the plants to a separate tub, spray
with malathion, wait 20 minutes, and then rinse and return to the

If you look at your roses, you will find them there too, but
they come in a variety of colors. The roses may harbor the green
ones while another plant may have red ones.


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Question #2>

Hi Carolyn,

I had an interesting experience with Duckweed several years ago. We
had a backyard pond (3 back) in which we used Hyacinths as our
predominant plant to control nutrients. We also pot planted some
Louisiana Iris in several places. We put in a dozen "feeder grade"
goldfish, about a dollar's worth. Of course both the Hyacinths and
the fish grew.

After the first year, we had to harvest and compost Hyacinths every
month or so during the summer. Finally, I tried a natural control
that a neighbor suggested. I grabbed a bucket of Duckweed from a
natural pond next door and dumped it in the upwind end of the pond.
The wind blew it up against the hyacinths and amazingly, it put
them in control. Our harvesting dropped back to just once or twice
a season (it's a 9 month season in S. Texas ). They just didn't
seem to want to grow against it, until the fish ate the Duckweed.

Then, of course, the neighborhood Great Blue Heron decided that the
pond was his private fishing hole and bagged a number of the fish
before we spotted him one night. Well, once again natural control
was the answer and we sent out the Lab to re-establish the
territorial pecking order. He became quite sensitive to the bird
problem and would even keep watch all night and whenever the Heron
showed up, he would wake us up rather enthusiastically to let us
know he needed to defend the pond.

The Duckweed however remained the silent control over the
Hyacinths. No one has been able to tell me why it works, but the
dreaded Hyacinths simply will not expand much against the Duckweed
barrier. Goldfish love it.


Answer #2>


What a great story! I do believe in natural control and this
epitomizes that belief. I had no idea that hyacinths would be
controlled by duckweed.

So, for all the people out there suffering with duckweed, maybe you
need to give it something to "control"... then you'll appreciate it
better. And I am sure you have nice clear water under there.

I was also told by someone, not sure about the veracity of this
yet, that duckweed removes all oxygen from the water.

Does anybody know something technical about this and care to


========== @SK Carolyn =================
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Happy Pondkeeping!

Brett Fogle
MacArthur Water Gardens

MacArthur Water Gardens
PO Box 3628
Alpharetta, GA 30023-3628

Posted by bfogle at August 15, 2015 04:27 PM