Date: Sun, 12 Jan 1997 12:21:11 +0100 From: Clarke Brunt <clarke@brunt.demon.co.uk> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg164$foo@default> Subject: Re: Red Spider mite?
On 9 Jan 97 at 1:49, Russell Elliott wrote:
> I was looking at my collection today, and to my horror,
> a good 50% of my VFTS were looking very sickly. Looking
> at them closely, most of the new traps that were emerging
> were dead, along with most of the old leaves. To be honest,
> I first noticed that they appeared to have more dead leaves
> than normal about three weeks ago.
Assuming you're in the northern hemisphere, then shouldn't your Venus
Fly Traps be largely dormant? Mine go semi-dormant in a greenhouse
with minimum 7C - not really growing, lots of dead traps (which I cut
off) but still a few live ones. Still, I guess you are the only one
who knows what your own plants normally do...
> Anyway, I *think* the problem is red spider mite. The leaves
> appear to have had their tissue "gouged" out (I'm only talking
> about cuts about 1mm in length) and they appear flecked with
> dead patches. I have also noticed tiny red dots on the plants.
> Since I can't find my hand lens, I cant quite make out what
> exactly these are.
Red spider aren't all that red, and you really should be able to see
them if you look closely enough. If you do see them though a
magnifying lens, they usually have a dark spot on each side. I've
never had these on my CP (I certainly do on cacti, and anything else
they take a fancy to). As you mention 'cuts', I wonder if thrips
could be the problem - another pest I have, though again not on the
CP. These are linear insects, maybe 1-2 mm long, black or yellow, and
often jump if disturbed.
> I was wondering if anyone knew of any biological or environmental
> control that is effective on them. I don't want to use Rogor,
> as that chemical badly set back my entire Sarracenia collection,
> and it is only now that they are just about recovered.
There is a predatory mite for red-spider called Phytoseiulus
persimilis which you can get in the UK (there is also one for
thrips), but I doubt the effectiveness of these unless you can
provide conditions more suitable for the predator than the prey. Both
thrips and red-spider seem very resistant to any insecticides on the
amateur market (in this day, if a chemical kills anything, then it
seems to be rapidly banned). Yellow or blue sticky traps are quite
good for thrips (which are attracted by the colour).
-- Clarke Brunt (clarke@brunt.demon.co.uk)
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