Bulb Scale Mite on Hippeastrum
Hans-Werner Hammen (Sun, 29 May 2005 18:32:56 PDT)

Hello Jim;

I live and I grow my hippeastrums in Germany.

I regret that I can not offer anything for the GROWING crop (nota bene)
which is fully endorsed by legality for the private gardener:

Dicofol ( in Kethane) is no more allowed in Germany and Avermectines (in
Abamectin) is not accessible for the private gardener.

Oxydemeton-methyl (a phosphorous-organic pesticide; in Metasystox-Spezial,
from Bayer) works and its use is principally legal for ornamentals outdoors
but it has to be used at the at less two- better 4-fold concentration
compared to the recommended. AND it has to be sprayed repeatedly BECAUSE you
can not eradicate these mites with it - although it is a systemic pesticide.
You can never obtain a sufficient agent concentrations in the older bulb
scale parts where the bulk of mites live and from where they emerge to seek
for new life space. But you can sufficiently protect the new growth by
spraying into the heart of the plant.

In autumn when I harvest my bulbs I treat them mechanically against these 8
legged critters. I first cut the leaves at a rather high level, then remove
all loose parts on the substrate surface and all dry and loose matter of the
bulbs, then I make the final clean cut to keep only a rather short bulb neck
and immediately spray with 10 % non drying oil in isopropanol. I use JoJoba
oil, medium light mineral oil works, too.

I spray on the wound and on the cleaned bulb and the substrate surface (My
bulbs stay in the grow boxes, keeping the roots undisturbed, during the
winter reposal. There is no hope that removing the soil has any curing
effect on the bulbs The spraying procedure has to be repeated several times
during the winter reposal because new spaces open between the leaf bases as
the bulbs dry. Spraying must be thorough but still so superficially that the
bulk of roots does not get affected.

The only eradicative means is the Hot Water Treatment. It is a well known
and simple procedure but depends on precise laboratory (or technical)
equipment. It is only performed on bulbs after the growth season. It removes
red blotch, eelworms and mites (but not virus). A disadvantage is that the
roots have to be removed before or are killed during the HWT. The bud
initials are usually not killed after 46 degC / 2 h treatment.

Reinfection from the environment is to be expected with high probability,
yes, sorry; I had my experiences in that, too...

Seedlings of amaryllid plants should be raised as far away as possible from
adult plants in order to stay completely free from this pest as long as
possible.

All the world is worrying about the red blotch: I never experienced red
blotch to develop on uninfested gardener's amaryllis bulbs. Red blotch is
"solely" a secondary infestation by the opportunistic Stagonospora although
it can become deadly for amaryllis bulbs particularly in cold wet weather in
autumn.

It seems that all knight star bulbs from commercial sources are infested
with mites. My experience, sorry. I worry about the mite, not about red
blotch.

Hans-Werner