agpcrv at agpcrv at
Thu Mar 30 19:57:26 EST 1995

In Article <mturner.511.000BDE80 at>
mturner at (mel turner) writes:
>In article <3ld3v9$lcs at> agpcrv at writes:
>>I am making this enquiry for a friend who is farming in a dry region of 
>>South Africa. His dam is overgrown with Azolla to the extent that the
>>entire water surface has been covered. Does anyone have any experience 
>>with eradicating this water fern?
>>Any help would be much appreciated
>If it is really Azolla and not Salvinia (better known as a serious  aquatic 
>pest), the farmer may actually benefit from allowing it to grow, periodically 
>skimming off the excess and using it as "green manure"--- Azolla has a 
>symbiotic relationship with nitrogen-fixing cyanobacteria (Anabaena azollae) 
>and thus can be used to enrich soil.

Thanks very much for your reply. I saw the plants about 2 years ago and was
informed by the farmer that they were Azolla. He may have been misinformed,
and since I cannot distinguish between the 2 genera myself, if you know of a
simple way to tell them apart, we would be interested to check them out.
If they are Azolla I am sure he would want to utilise them for compost. However,
if they are Salvinia, is there an effective, less labour-intensive method than
dragging, to get rid of them. He has a concern that the plants will suffocate
his fish as well as silt up the dam.

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