Fungus on Elodea

jgresens

Junior Poster
Dec 21, 2012
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Hi all
I work in a lab and we keep Elodea canadensis in large tubs of water (dechlorinated with activated charcoal) under full-spectrum light. We use the plants mostly for preparing slides, or to provide to teachers for photosynthesis/cell division lessons. Typically we buy from a vendor on a regular basis and re-stock our tubs.

Recently I've heard that the slides-folks are seeing fungus on their slide-preps made from my Elodea. They've been making these slides for years, and have never seen this issue before, so I'm looking at this as an early warning of something that could further develop if not addressed now. I'm not seeing much in the way of die-off with the plants themselves, but I'd like to nip this fungus-issue in the bud (pardon the pun). Incidentally, I think the fungus came in on a shipment from our vendor. I'm following that up and am looking at replacement but would like to still look at treatment options to see if I can get rid of it on the plants.

Does anyone have any experience with fungicides that can be used for aquatic plants? I know salt and vinegar are both pretty good at eliminating fungus, but they can't possibly be good for the plants.
Would love any input you can provide.
Thanks and happy holidays, al!
-Jill
 

aquabillpers

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Jan 24, 2005
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I wonder if soaking them in a 5% bleach solution for two or three minutes would help? Anybody have any thoughts?

Bill
 

Rhizomorph

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Feb 24, 2015
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Are you sure it's fungal? Some of the water moulds look like fungi but aren't -- and this is going to effect how you go about treating it. Most of the treatments typically aren't great as all these organisms are eukaryotes (and thus pretty similar) so you can't easily target cell wall synthesis etc. -- Rhizomorph.
 

Tom Barr

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Jan 23, 2005
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Jill, selectivity is what you are after. You need something that will kill the pest and not do much harm to the plant.


1. Sometimes biocontrol is very effective. Cherry shrimp are very effective, bred easily and require little care. They will pick and remove periphyton from leaves. Better them, than you.


2. House hold chemical control: Peroxide works fairly well, this would be a better alternative than bleach. Dipping time will vary, but generally 10-30 seconds diluted to 0.3%(3% is standard stock). A bit of trial and error and you should be able to get results there.


3. Glutaraldehyde also will work, it will melt the leaves back some on the plants, but should not kill it. I dosed a 2 ppm on this plant species, Hydrilla and E densa back in 2006 at the aquatic weed lab. Even at higher doses, I was not able to say it would kill the plants(any of the 3 species). It did slow growth and kill algae and any other periphyton.


4. Fertilizers. Sometimes, higher dosing of Boron can help with fungus, this assumes that it is fungus. Adding fertilizers, CO2 etc, can help grow the plants better, and provided healthier samples. This might not be the best method since this requires more labor and trimming, management etc.


5. Vendors just go grab weeds from a pond or lake, maybe a river. Sometimes they might sit on the plants a bit and put them in a tub, there, they can rot some.


We used mostly E densa in the lab for students I had, as the leaves are larger and a little bit easier to view, but it does not matter much. We have lots of E densa available,E. canadensis is less common here. The Glut additions will clean the plants up some, but also melts them back. Due to the volume of plants you get, dips are going to be tougher also. I think using the peroxide dips and some biocontrol(Snails, shrimp etc) would be the best option. You can use the shrimp and snails for other lab experiments and teaching aids also. The Shrimp are too small to use like cray fish for dissections. But they are good for genetics, LD50's, herbivory per unit area for periphyton and a few other questions and concepts for students.


Hydrilla, Egeria and Elodea all have leaves that are 2 cells thick, so most chemicals need to be rather mild, this means the target pest will be harder to get rid of. But, these are really fast growing weeds.


6. Trim off the older leaves and keep only the nice new tops/tips and dip in peroxide and add to a clean sterilized tank.


I do not think the fungal issue will become a problem really, just that students might get distracted with the other items in the slide view.


Fungal issues in planted aquariums are pretty much non existent. They are there, just they are not a problem. For slides, that might be another issue.


I would suggest #6 there.