Bertie Doe wrote:

For the last 2 seasons, the flea beetle has ravaged most of my tender leaf
veg - even the leaves of my horseradish plants, looked like a swiss cheese
plant.
I've tried liquid deris, but to no effect. I'm prepared to try something a
bit stronger, so any ideas would be appreciated. TIA.
Bertie

You have tried the sticky yellow traps I take it, hold it over the plants
and give the plant a tap, the flea beetles jump up and stick to the trap
usually offers a certain level of control. You could even place some
sticky material on paper under the plants first to catch any that make it
back to ground level.

Duncan