Topic: Glasshouse Whitefly...what would you do?

[aob9]

It seems I have committed a cardinal sin. I "acquired" strawberry runners from a friend and potted them up for an early crop in the glasshouse. Today I discovered (for the first time in ten years owning a glasshouse) that I have whitefly on the strawberry plants. As they are in pots I took them outdoors and drenched them with Horticultural soap. On inspection of my tomatoes, peppers and cucumbers I find no infestation, just the odd aphid but I can live with that. My question is .....would you remove the strawberry plants now before the infestation spreads or would you continue to treat with horticultural soap and order some Encarsia.

Incidentally, on inquiring my friend told me the runners came from a poly-tunnel which explains how the little buggers hitched a ride into my glasshouse. I had incorrectly assumed that the runners came from outdoor parent plants.

[ed dibbles]

I would recommend you don't put the strawberry plants back in the greenhouse since it would take more than one dose of insecticide to erradicate them.

They will have laid eggs that take up to 3 weeks to hatch so you may kill the exisiting population, re-introduce them to the greenhouse only to find they are back again very quickly.

Also don't assume the other plants in the greenhouse aren't infested for the same reason.

Once you have them they are almost impossible to erradicate (encarsia is a control not a cure). I had them a few years back and the only way I eventually got rid of them (after trying a whole host of things) was to leave the greenhouse and all the plants in it unheated for winter. I lost a lot of plants but got rid of the whitefly.

Greenhouse whitefly don't like outdoor conditions (or freezing conditions)  so in a couple of months your strawberry plants should be clean.

[chriscross1966]

Marigolds seem to drive them off, and yellow sticky traps catch a lot too, but ed dibbles is right, the only real way to get rid of them is to not heat through the winter.... I have a break in mine programmed for each year between early November and late December to try and get them gone...

[laurieuk]

If the white fly came in with the strawberry plnats then is more than likely to be the outdoor fly like the one on brussel sprouts etc. and should not infect indoor plants but you cab use the encarsara wasp to control. I have used this in the past and found it very good. I fyou do use the wasp make sure you have not sprayed recently and not got yellow pads up.

[aob9]

Thanks for replies. I moved them outdoors because they also had a lot of aphids. There was a little too much pest activity for me to be comfortable with leaving them there. I have been very lucky with my glasshouse and poly-tunnel  for some time now and I decided to be ruthless rather than risk a Summer trying to deal with pests. I have them covered (overnight) with fleece outdoors to help them adapt. Yellow sticky traps ordered.

[Aden Roller]

Can you still buy those small smoke cones that I seem to remember using long ago to clear my greenhouse of some pest or other?

[chriscross1966]

My local independent GC has them

[Aden Roller]

From what I can remember they work pretty well but the greenhouse needs to be empty and then well ventilated for 24 hours after use.

They certainly pong!

[laurieuk]

As only adult white fly are killed with smokes or sprays you do need to repeat whatever you use at intervals of 4-5 days as you will have eggs and larva hatching out after you treat the greenhouse. Depending on the temperature what the interval will be.

[Aden Roller]

I'll not be using the pong nasty smoke things again - they were OK but....

Best to keep ventilation up and avoid chance of taking pesky fly in there in the first place if possible.

When they do visit, or even before they are spotted, yellow sticky traps work well and I prefer a spray of very dilute soapy water.