"Chris" wrote in message
...
Hi,

I'm quite new to both bonsai and hydroponics, but I've been keeping a
couple Ficus, Willow, and Serissa alive for a few months in an ebb and
flow setup using lava rock gravel as the medium and supplemental
fluorescent lighting.

I change the water about once a month, but recently I've noticed a
problem. A fine white fluffy mold has started growing on some of the
roots and leaves. This is really perplexing me, because I spray each
plant with a fungicide every few weeks.

I don't think you have mold, sounds like mealy bug. Your spray probably
won't get rid of it. Here's a link and some info:

http://www.growingedge.com/magazine/...hp3?AID=170448
One of the most highly visible and familiar pests of hydroponics plants is
mealy bug. Growers who have not come across these pests before often mistake
the first signs of these pestsÑa white, waxy or floury looking depositÑas
some sort of disease rather than an insect pest. While this white cottony
growth does look similar to a fungal growth, it is in fact the waxy covering
of the mealy bug. The adult female is about 3 mm long, oval and wingless,
with short antennae and a fringe of filaments around the body. One of the
most common mealy bug species found in hydroponic systems is the long tailed
mealy bug, which has two very long filaments at the tail end of the insect.
Underneath the white waxy covering the insect is usually yellow or grey and
may have a darker strip running down the middle of the back.

Most mealy bugs lay eggs, up to 600 at a time, in a loose cottony waxy
deposit on the undersides of the leaves. As the young mealy bugs settle down
to feed they begin to exude the white waxy material that soon forms a
covering over the whole body.

Some common types infesting hydroponic systems can produce live young, and
populations can build up rapidly. Each female long-tailed mealy bug, for
example, can give birth to as many as 200 crawlers, with as many as 3-4
generations per year, depending on climate. Under cooler winter conditions,
the insects tend to retreat under bark, into crevices and other places to
hide until temperatures warm up.

These insects have piercing and sucking mouth parts which they use to suck
sap from the plant. A heavy infestation can suck a plant dry, stopping
growth and yellowing foliage, leading to plant death.

Mealy bugs feeding will often disfigure foliage and fruit. These insects
also excrete honeydew, which forms a sticky deposit on plant leaves. Sooty
mold may eventually grow on the honeydew, resulting in a black tacky mess
that inhibits plant photosynthesis.

The best method of control is regular inspection of plants and taking action
as soon as mealy bugs are detected. Mealy bugs are difficult to control with
conventional sprays because the adult is protected by a water repellent waxy
covering. In addition, they tend to hide in leaf axils, buds and other
places where sprays don't penetrate for adequate control. For an individual
plant, its often recommended that mealy bugs be brushed with a solution of
alcohol or methylated spirits, which dehydrates the pests. However, this can
be extremely time consuming and often doesn't provide adequate control.



Good luck!

Val