Topic: glasshouse red spider mite

[moonbells]

Has anyone any experience on GRSM and biological control? I'm looking at the predatory mite from various suppliers and their description of the numbers needed seem to vary. I've got an endemic infestation - each year they overwinter on something (the aspidistra's been hit really badly this time) and then munch their way through my cucumbers each summer. I've just spotted the telltales on the aubergine already, so enough is enough.

But how many mites to buy? 1000? 2000? Anyone any idea? (Conservatory is 9' x9')

moonbells

[undercarriage plan]

Hi Moonbells, before forking out loads of dosh, have you tried damping down the greenhouse?  Spider mite thrive in dry conditions, they hate it when humid.  Try keeping the base of the greenhouse damp.  Hope this helps.  Lottie

[Doris_Pinks]

Been spritzing my Aubs with water every other day, and have them sitting on gravel in a tray which I moisten with water, I got mited last year so am hoping I can conquer this year!

[giantseye]

Yes I agree with what has been previuosly said.  The greenhouse is too hot :o

Do you have adequate ventilation, or could you create any extra vetilation in yo ???ur G/H

[Mrs Ava]

My conservatory suffered year before last, since then have tried to mist daily, or let the kids have spray fights in there and do the job for me!  ;D  Seems to keep it just about under control.

[moonbells]

Hi Moonbells, before forking out loads of dosh, have you tried damping down the greenhouse?  Spider mite thrive in dry conditions, they hate it when humid.  Try keeping the base of the greenhouse damp.  Hope this helps.  Lottie

It's not a greenhouse. It's a conservatory, so damping down the floor is not really an option. It also has no openable windows so ventilation is entirely by opening doors. I'd love to know which twit of a firm built it... but that info wasn't given to us by previous occupants of the house.

And most of the time it's incredibly humid (we can't keep wooden structures inside as they go mouldy). I've tried most tricks over the past few years and the RSMs still just love it in there in summer.

It's confounded by the temperature going well over 30C and then opening doors to let heat out - that lets humidity out and so it dries out.  And since we run freezers in there (operating temp range up to 32C) we can't afford to keep the doors shut and temperatures too high.

Hence the desperation tactic of getting predators. Least I'll get shot of them for a season and my poor houseplants can have a chance of recovery. (Aspidistra is going outside for the summer in a week or two,  bird of paradise I can't put out as it's growing seed pods and grey squirrels will have them otherwise. )

moonbells

[Marley Farley]

 :) Hi moonbells Check out about the temperatures that the predators will be in as they don't work under some conditions, I think it is hot & dry but not sure :)

[tim]

Here we go - thoughts only!

1. Predators will not rescue a bad situation.
2. You can't use them until the temp is up to (?) 60F, by which time it's often too late.
3. They don't normally get bad until growth is up to the ceiling & you can't see them! But you can see the webs at the leaf/stem juncture. In which case bin the whole leaf.
4. Defenders - et al - tell you how many for how big.
5. I've never known RSM 'munch'. Are we sure that this is RSM??
6. Can you move everything out of the conservatory, for a moment in the Spring, so that you can disinfect? But the smell of the disinfectant would be unacceptable?

[moonbells]

Tim> 1. Predators will not rescue a bad situation.
I know - that's why I'm trying to get them *before* stuff dies this summer,  just as I manage to evict a lot of the overwinterers into the garden.

Tim>2. You can't use them until the temp is up to (?) 60F, by which time it's often too late.
Conservatory is a heated one for tropicals - not just frost-free, so mites overwinter very cosily  :( I know this one.

Tim>3. They don't normally get bad until growth is up to the ceiling & you can't see them! But you can see the webs at the leaf/stem juncture. In which case bin the whole leaf.
I'd have to bin whole plants, that's the problem. You ever tried to de-web a herringbone/prayer plant (maranta leuconera)? The shrivelled leaves stay put and provide hiding places for mites even if you do spray the thing.

Tim>4. Defenders - et al - tell you how many for how big.
Have plumped for large number as apparently once there's webbing, there's a lot of RSM present. Hopefully will be able to report on progress.

Tim>5. I've never known RSM 'munch'. Are we sure that this is RSM??
Oh they are - just me being inaccurate in my terminology! Suck doesn't sound nearly as polite... and may hit the censor anyway :)

Tim>6. Can you move everything out of the conservatory, for a moment in the Spring, so that you can disinfect? But the smell of the disinfectant would be unacceptable?

No, that's the problem. I have three bougainvilleas permanently wired over the patio door to the lounge, a grape ivy ditto at the other end, a hoya over the door to the garden, plus orchids, bird of paradise plants, the aspidistra, prayer plants, hippeastrums and achimenes. Plus all the overwintering fuchsias and agapanthus. Then I cram in all the sowings... and cukes and aubs so I really do have a bit of a problem! Once upon a time I fumigated it (fewer plants then!) and the fumes got into the house through the patio doors and stank the house out for weeks. Course you can't buy the smoke cones any more either and I'm now rather more organic...

I shall play with my predatory mites and see what happens. 

There might even be room for humans too once I've cleaned it out! (I need a greenhouse)

moonbells

[tim]

Sorry to give you tired fingers - but it's good for the mind??

And, of course, when I said bin it, I was thinking in terms of our cus.

[moonbells]

Sorry to give you tired fingers - but it's good for the mind??


And, of course, when I said bin it, I was thinking in terms of our cus.

 ;D ;D

yes, last year I was binning dying leaves as fast as new ones grew.  I used to be able to get sufficient cues for two from one plant but since the RSMs appeared I've had to get two per season simply because the cropping is so much poorer.

Course I *would* like home-made veggie sushi hence needing lots of cues...

If the predators work then I'll have two full-steam ahead plants and there'll be screams in the shed of ANYONE WANT CUCUMBERS?!!!!!!!!  ;D ;D ;D ;D

moonbells

[portway farm]

There is a spray that you use on chickens to prevent / remove RSM I would assume if it is safe for chickens it should be ok for plants. There is also RSM powder. Not much help am I. But its all I can think of.

[moonbells]

There is a spray that you use on chickens to prevent / remove RSM I would assume if it is safe for chickens it should be ok for plants. There is also RSM powder. Not much help am I. But its all I can think of.

Thanks - the trouble is I'm organic where food is concerned and so don't want to spray *anything* on the edibles in the conservatory. 

We were looking at the aubergine this morning. The patches of RSM now seem to all have either black flecks in (which I hope are predator eggs or larvae) or predators wandering about.  Hopefully it's working.

moonbells

[tim]

Sounds hopeful - failing which - too late? - 'Eradicoat'??

[moonbells]

Sounds hopeful - failing which - too late? - 'Eradicoat'??

Something I'm considering getting for next season - a few sprays of that to dent the number of RSM and then an introduction a week later of a small number of predators.  That should keep them at bay!

Had great fun last night trying to get temperature back up to 20C and humidity up. Manic spraying of plants with water and a fan blower on full tilt in the corner.

It's a bit silly - gets to 35 in the day (too hot) and then drops to 15 overnight.  Though from what they are saying it's going to be a bit warmer come the weekend...

moonbells