Re: Cryptocoryne affinis leaf drop

>From the description the leaves appear healthy, but abscise from the 
>plant and float to the surface? Could the abscission be due to some 
>physical action, such as a parasite chewing through the base of 
>the leaf? Transfer of infected material from one aquarium to another would also 
>transfer the organism of interest. 
>Microscopic (even a hand lens might work) examination of the 
>infected material might provide some insight to the source of the 
>problem. If you don't have access to a microscope I could examine some of 
>the infected material. I have an extra aquarium in my office that I had 
>been planning to switch over from a Rift tank to a planted aquarium. I 
>could bring some crypts (affinis and other species) from home, establish 
>them and then add some of your contaminated material if initial 
>observations prove unsuccessful.  
>Ken McNeil
>Horticultural Science Department                 (612)624-2715


Many aquatic plant enthusiasts would be eternally grateful if you can 
figure out what causes the described problem with Cryptocoryne. This is 
the so-called cryptocoryne disease that affects many (or all?)crypts, but 
particularly the affinis species.All or part of the leaves appear to melt 
over a period of several days. It has been hypothesized that the problem 
is attributed to a virus and the University of Florida was even given a 
grant by the Florida plant growers to try to isolate one. As far as I 
know their results have been inconclusive to date. It has also been 
suggested that a change in water chemistry can cause the melt down. This 
is because a water change or introduction of fertilizer or other chemical 
change can sometimes trigger it. Nitrate is often mentioned. The problem 
can also happen when another crypt is added. I have experience all of the 
above. The onset of the problem following addition of a new plant does 
suggest allelochemicals, but could also relate to some other chemical 
that comes from breakdown of the new plants leaf. The water conditions 
may also be a factor, because hard water/soft water and concentration of 
certain elements like copper can make a difference. One way to reduce the 
chance of this occuring is to remove most of the leaves from new plants 
introduced into a tank with crypts. This is a most perplexing problem. 
Contact me if you have any new ideas.

Neil Frank