These are some of the problems that we've struggled with while growing our own plants.  The pictures
show the symptom, treatment regimens are shown adjacent.  
Oopsies!  Common problems with Lotus

Aloha to all our mainland
visitors and people around the
world!  Unfortunately, most of
the problems with growing
Lotuses have to do with their
delight in high temperatures
and long daily exposures to
intense sunlight, and the
inability of your plant to find
these essential things at your
house.  

There are only a few places in
the world that qualify on both
counts and Hawai`i is definately
one of them.  If your plants are
having trouble with your climate
our best advice is... move!  Lots
of room here!
Rainbow Falls  Kaua`i
Aphids - These nasty little things are by far the most common
problem that we've encountered with our Lotuses.  You can usually
find them on the stems and undersides of the leaves.  Thankfully
they're little more than an eyesore if treated promptly.  There are a
number of off-the-shelf treatments for Aphids but at our nursery we
exclusively use Volk Oil to treat all our plants.  It's mostly non-toxic, it
mixes and applies easily, and so far it hasn't affected any of our
fish; including our goldfish which are extremely sensitive to
environmental toxins.
Pale Leaves -
This is one that
you shouldn't
see much - its
caused by
overfertilizing,
which is very
hard to do with
Lotuses.  
Curly Leaves -  This is the most common way in which the Lotus
shows that it is not happy, and could have several different causes:
1.        Your roots have dried out.  If this happens, the plant cannot
be saved.
2.        Your roots are boiled. Depending on severity, the plant may
be saved.  Take steps to lower the temperature at the roots.  
Something more permanent than ice is needed, try shading the
water or using a deeper pool.  Don’t forget that the pond container
itself might be fully exposed to sunlight and contributing to the
problem; that's the case with the top photo on the right.
3.        Someone or something has been fiddling with the roots.  
Unless you really know what you’re doing, it’s not a grand idea to go
poking about in the Lotus’ root structure during its peak growing
season.  They don’t like it.  If you have overly inquisitive fish in the
pond (such as Koi) you may wish to have a quiet word with them
about digging in your plants.
4.        You're not using enough fertilizer.  The plant in the bottom
photo is suffering from this.  Add some fertilizer and the plant will be
very happy with you!  
Slugs - Cory's
Slug Bait,
spread liberally
around your
pond, should
clear this up.  
Don't put it in
your pond, it will
kill the fish.