On 6/3/09 23:47, in article , "DerekW"
wrote:


"Sacha" wrote in message
...
On 6/3/09 19:05, in article
, "Judith
in
France" wrote:

On Mar 6, 5:26 pm, Sacha wrote:
Any chance that frogs and/or tadpoles eat duckweed?!
--
Sachahttp://www.hillhousenursery.com
South Devon
Exotic plants, shrubs & perennials online

Straw will clear it. Don't know about Frogs though.

Judith


It's quite a large pond and barley straw hasn't helped in the past - or
not
enough, anyway. I suppose we could try dragging some clumps of it across
the pond.....

--
Sacha
http://www.hillhousenursery.com
South Devon
Exotic plants, shrubs & perennials online

Are we confusing duckweed Lemna minor with algal blooms and filamentous
algae which barley straw does control.

No, what we have is duck weed. And it's worst on the pond we don't want to
put fish into!

We had huge problems on the shoot with a pond being covered with a thick
carpet of duckweed and despite a serious effort to remove it during which
we scooped off around 60-80 kilos a week over a month or more it came back
within days.
This year 2008 it had all but disappeared the only difference being the
introduction of proper pondweed the previous year which has finally taken
hold and colonised the margins it could be the heavy rain or the weed
reducing the nutrient level or even overspray when our farmer applied
herbicide (unlikely he's extremely careful about when he sprays and the pond
is about 30 yds from the nearest cultivated area) We do get a lot of duck
but in the covered years they didn't make an impression on the carpet and
they positively avoided the pond we have few frogs ( heron activity) and no
fish.
Common Koi and Grass Carp do eat duckweed and I did a little research and
found freshwater shrimp also do .
One other suggestion about the sudden reduction in duckweed under windy
conditions when the water gets a little ripple the weed stacks up in layers
at the windward end a good time to scoop a pile out!
DerekW

Absolutely right. Last time we had a gale that blew the duckweed in the
right direction, I noticed it as I came in through the gate in my car -
though "must go and scoop that off" and promptly got diverted so never got
round to it. I'm waiting for the wind to be in the right direction because
it had it all arranged in a neat little pile for me!

--
Sacha
http://www.hillhousenursery.com
South Devon
Exotic plants, shrubs & perennials online