Dennis Kramb
Sat, 11 Dec 2010 09:00:51 PST
I'm battling what I believe to be a thrips infestation on my gesneriads.
Today I noticed a couple plants dying back in my terrarium which is located
in another room.  Lo & behold there's a huge quantity of the same beasties
on those plants.  I only occasionally see flying bugs, but what I frequently
find are these orange worm-like organisms crawling on the leaves, they are
incredibly small, flexible, and relatively fast.  In my terrarium they were
on my Hippeastrum seedling in huge quantities... more than I've seen on any
other plant.

So first of all, does this sound like thrips to you?  And second of all, how
would you battle them?  I never use harsh chemicals, so if that's my only
choice I will just give up growing those plants.  I've been trying to do
immersions in hot soapy water and then isolating the plants.  But it is not
totally effective.  (I started this treatment when I thought the problem was
foliar nematodes.)  Clearly I need to improve my tactics.

Plants affected the worst:  Hippeastrum, Gesneriads (all except Chirita (so
far)), Rex Begonia.
Plants apparently not affected:  Orchids, Irids, Passiflora, Eucharis.

Interesting that the Hippeastrum was affected but not (yet) the Eucharis.
It could simply be the humidity & warmth of the terrarium vs the dryness and
coldness of the windowsill with the Eucharis.

I can't pinpoint when the problem started, but I am suspecting it was a
loooong time ago, and I wasn't alert enough to see the initial signs.  Now
I'm upset it seems to be in 3-out-of-4 of my grow rooms.

On the Hippeastrum they created dark red streaks on the leaves.  On the
Gesneriads and Begonias the leaves basically turned necrotic (black)
wherever they were feasting... from edges outward, or anywhere really.  It
seems to take them a long time to cause lethal damage.

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