This is of the other common problems I occur, Fortunately at the moment it only seems to occur on the Pepper plants and only in one greenhouse (The plastic one, Though I’m not sure why)
I have tried some of the ideas displayed around the internet such as using a solution of water & washing up liquid, Unfortunately not which must success.
The water and milk solution I use on the cucumbers above seems to help slightly.
At the moment though the way I get rid of the whitefly is quite simple albeit a little long winded. I purchased a rechargable low power portable vacuum cleaner normally used for vacuuming cars. Now every week or so I go around the plants with Whitefly and vacuum all the whitefly off the plants.
This is 100% successfully, Although you do have to make sure the vacuum cleaner is low powered otherwise you’ll suck up the plant leaves as well .
This is the most common problem I encounter, Partly due to the lack of recirculating air in the greenhouses.
This fungal disease attacks just my cucumbers and creates a powdery substance which covers the leaves and eventually kills them if left untreated. Fortunately after several years of the problem I seem to have found a good solution and a simple one at that.
When the problem starts to occur, I make a solution up of 1 part milk to 10 parts water, This is then liberally sprayed all over the leaves underneath and on top.
So far (fingers crossed) this has helped tremendously.
I simply repeat this every few weeks or so if the problem starts to occur again. Just make sure you empty the container you’ve used after spraying, Otherwise the container gets a little smelly after a few days. As I’ve found out already.