Skip to Content
Weed control, management, ecology, and minutia
by jacquelyn bruce
on April 17, 2011 at 11:38 AM
I have an acre+ pond south of Grass valley that currently looks like a market square with russet azolla. I've become quite the expert on this symbiotic package since the beginning of my personal infesttion last year. I harvested it all last season and put it in the composter where it does indeed make lovely compost which is, however never really quite completely composted as little green leaves of azolla are sprinkled throughout the mixture even after many months. During the season I average two large buckets a day and, on warm days, I'm falling behind as this stuff increases exponentially. I did enquire about stenopelmus rufinasus last year and was met with either total ignorance of this control or the assurance that this weevil would not be allowed. I am very pleased to hear of its "native" existence and would very much like to give it a go in my pond as I am already behind the azolla ball this early in the season. I really seem to be the only pond so severely impacted by this overly-beneficial weed and my little otherwise faily well-balanced ecosystem is bound to suffer as a result. As an aging widow with twenty-three acres to steward organically, I need all the littler helpers I can get and a passle of little weevils actually described as "cute" on one British site, would be just my cup of tea. Come on Davis, lend a girl a hand!  
Sincerely and somewhat hysterically,  
Lynn Bruce
by Steve Osborn
on May 11, 2011 at 9:51 PM
Is there any way to obtain azolla weevils in California? My half-acre pond in Santa Rosa is completely covered with azolla, and has been since last year. Do the researchers in Davis and Albany have any weevils they can spare or sell?
by tropical water lilies
on May 31, 2011 at 12:09 PM
We use azolla here as fish food. Our goldfish do eat it along with duckweed. In the summer it turns reddish.
by Claudia
on July 6, 2011 at 10:47 PM
I live in Mendocino County, have a natural, one-acre pond (fed year round by aquifers and enhanced by seasonal runoff) that was recently infected with ludwigia, duckweed & azolla, it's a long story... However, I scooped out all I could last year & went back in on the 4th of July 2011, to check & control whatever survived, ludwigia aside, I was surprised and happy to find minimal remnants of the floaters, duckweed and azolla.  
I just read that koi love to eat azolla and duckweed. That may explain why azolla and duckweed have not proliferated on our pond, as we have 12 huge koi (3 to 4 feet in length) living in our pond. My pestilence scooping abilities aside, it seems that koi may be the critical element deserving credit for containing these pesky floating invaders....  
Knock on wood, but right now our pond's water clarity is excellent & all seems to be in balance. Anyone else noticed similar 'koi' results?
by Dr Quazi Taheruzzaman
on January 7, 2013 at 8:53 AM
Azolla is an important aquatic fern,has paramount importance for Anabaena azollae which can fix molecular nitrogen from the atmoshphere.So, it can be used directly to the agriculture field as biofertilizer.Besides Nitrgen, it can give a considerable amount of P and K. So it can be used as NPK tablet for the cultivation of Rice.  
As it has a considerable amount of Protein ,it is a good feed of fish,duck,hens etc.  
Azolla can be used as a potent candidate for removing Phosphorous( a key element of eutrophication )from polluted water.  
It can controlls weeds in rice field and mosquito in open water.  
So, Azolla is a potent candidate for SUSTAINABLE DEVOLOPMENT.
by Jim Wilder
on January 12, 2013 at 11:09 AM
We have had limited success in Sonoma and Napa counties manually removing the Azolla and treating the water with sludge digesters to help remove nitrogen from the water thus 'starving' the Azolla. Water aeration also helps. We prefer compressors on shore sending air to bottom diffusers- cheaper and covers more area.
by emma jackson
on July 6, 2016 at 11:59 AM
Hi I live in Dorset and have a pond which is about l acre, I had enormous problems with Azolla and about 4 years ago introduced the weevils, together with some grass eating carp! The combination worked, and its only been this year that the invasion of Azolla has started again - with a vengence. Having spent all day raking off the stuff to give the fish some free space to breathe, seriously thinking about reintroducing more weevils.
by Nora Petrich
on September 10, 2016 at 9:48 AM
I would like to locate an outlet that sells: weevil (Stenopelmus rufinasus). My web search did not produce any sellers.  
Thank you!
by Penny
on May 23, 2017 at 7:57 AM
Has anyone had experience with ducks controlling Azola. I know it loves phosphorus. I'm wondering if they can eat more than the nutrient load would produce. We have a 1/2 acre pond we are thinking of introducing 25 native mallard ducks to controll the azola. Any thoughts?
Reply by John A Roncoroni
on May 24, 2017 at 9:27 AM
if you can keep the ducks in the pond they may be able to keep it down, but I don't think they will ever control it because it reproduces so quickly
by Penny
on May 23, 2017 at 8:05 AM
Has anyone had experience with this weevil: Stenopelmus rufinasus? It supposedly controls azola and only eats that plant so apparently isn't harmful to the environment. Is it allowed in California?
Reply by John A Roncoroni
on May 24, 2017 at 9:31 AM
Penny, I haven't seen good control from the weevil. I am pretty sure it is native to California, so it may already be there. it probably keeps it in check in nature, but does little for the 'explosion' in populations we can see in small ponds in late winter/spring
by Betsy
on June 8, 2017 at 2:10 PM
Penny, or others I will pay shipping and handling for a smallish shipment of your pre-weevil azolla. We are converting an old in ground swimming pool into a pond. We are in NW WA so won't have the same issues you do. I can't find any locally. I found some duckweed in our local slough that is doing well, the fish keep it under control, it's in a good balance. Azolla has properties that will help our new pond to become more stable. Thanks for your consideration.
by Sonja Lewis
on March 25, 2023 at 3:56 AM
If the Azolla is bothering you that much on your pond, take a kayak or rowboat out and rake some of it up. It makes good livestock and poultry food. Azolla might look bad to you, but it's producing oxygen and food for many different native animals. Thick stands do outcompete SUBMERGED aquatic plants--but emergents like water lilies and ornamental reeds would happily coexist! Also, Azolla produces substances that some mosquitos don't like, so fewer mosquitos lay eggs there.
Leave a Reply:

You are currently not signed in. If you have an account, then sign in now!
Anonymous users messages may be delayed.

Security Code: