How to Prevent Flies on Vegetable Plants

[wax]

Hi,
Im wondering if there is a preventative method to keeping flies off my veg plants.
I have tomatoes, courgettes, gherkins, peas, onion, garlic spinach, beetroot, rocket and carrots. Ive tried to companion plant in the raised bed (onion, garlic spinach, beetroot, rocket and carrots) and once hardened off and planted out I plan on putting basil close to my tomatoes. I've read about treating the pests once they are there, but is there anything I could spray on the plants that would prevent a lot or at least some flies from bothering in the first place?
Ive ordered some neem oil and I have some ecover washing up soap to make a spray to try and get rid of the leaf miners that have pretty much ruined my first spinach crop but I am about to plant a new crop and if there was a way to stop em before they lay their eggs then that would be great.
Is the neem oil spray good to use as a preventative measure as well as a treatment?
Im mostly concerned about the tomato and spinach.
Oh, and of course, organic is preferable.
Thanks!

[mcdood]

Hi Wax, Of those plants you are growing, my concern would be - carrot fly - you will need an insect mesh barrier to stop that. The Allium leaf miner 1st phase is over now and your garlic and onion should be harvested before the next batch in September.

[Jungle Jane]

Tomatoes are carnivorous plants the flies are motionless stuck in the hairs,they die fall off & fertilise the plant. I always leave the flies on they're fine. The only tomato pest I’ve seen is the brown line bright eye moth caterpillars,they eat so much leaf. Ive never grown spinach but leaf miners are inside the leaf I don’t think spraying anything will work but you can usually see the black dot/insect at the end of the trail & crush it or cut them off & destroy.

[Snoop Puss]

Some good advice above. But what kind of flies are we talking about? Aphids? Are they already on the plants?

[wax]

Well, I'm just hardening my tomatoes, courgette and gherkins off now and when I bring them back in every day they all have quite a lot fo flies on. Black flies, green and white too. Not huge amounts, 5-10 per plant.
That makes sense about them getting stuck there. Ive been picking them off every evening as I was worried about them laying eggs. Probably paranoia from reading about whats happened to my spinach. But now you mention it, they must be stuck to the plant, none try and escape when Im picking them off.

Ive read about the leaf miners and neem oil. Apparently, the infested leaves should be cut off got rid of but a few kept in a zip lock bag. Keep an eye on the bag and when you start to see flies buzzing around in there its time to spray once a day for a week. The neem spray (neem oil, water and soap) disrupts their life cycle affecting breeding and suffocates them. I think I read that there will be 3 or 4 life cycles of these pests over the season, so I'm keeping my eye on that bag of leaves for the flies then I'll start spraying the spinach.
Thanks everyone for their help. Its my first year growing and running in to this problems and everyone here is very helpful.

[Scarlet]

I would personally leave your oils and sprays for things that really need it.
If spinach has a leaf miner you aren't going to eat the leaf that has it. So pick them off and dispose of them - that is preventative.

Any lotion and potion you use will most probably kill off the good insects too.

Using preventative measures that don't harm beneficial insects is the way forward. Buy in the correct mesh to cover your crops.
I've never really used much more than washing off with a hose and generally my plants do fine.

Black, green and white flies in toms, cues and courgettes? ( I've grown courgettes and gherkins for many years and never had an aphid issue - have you got a photo?) Just keep washing them off under a shower tap and then stand outside during the day.

[Snoop Puss]

Me, I'm a big squisher and squasher. Even leaf miners in spinach and other plants I'll squash in the leaves to ensure they're dead, while leaving the rest of the unaffected leaf to carry on photosynthesising. If necessary, I wash the squashed 'residue' off.

[wax]

Apparently neem oil is safe for most other insects. Does anyone have any experience to the contrary?

The green flies were on the courgettes and a few on the toms.

Can only find them on the toms right now.

[Scarlet]

It's not a great number - squish them and blast off in the morning and leave outside during the day.
Try not to get them on your other plants by keeping them separate until they have gone.

[Snoop Puss]

^Seconded.

[Jay-ell]

Me, I'm a big squisher and squasher. Even leaf miners in spinach and other plants I'll squash in the leaves to ensure they're dead, while leaving the rest of the unaffected leaf to carry on photosynthesising. If necessary, I wash the squashed 'residue' off.

Would squished bug count as a foliar feed? It is high in nitrogen.