bug killer on veggies

[crisgal]

my little cucumber plant has got a fungus, rot or bug of some sort. I've bought some organic bug killing stuff and have sprayed it.
It is next to a courgette though (which looks very healthy) and I'm worried that this may get it.
Is it possible to use the spray as a preventative? Or do i just wait to see if any other plants develop problems?

[Hawkwalk]

that depends on what the problem is and what type of spray you have. If you have picked up a bug gun and you have a disease then it wont work.

If you have a contact spray then that will not give any protection. It only works by contacting the thing it is trying to eradicate.

Please explain the symptoms you are seeing on the plants and what you have purchased and I can help further.

[crisgal]

the lower leaves on the cucumber have gone a speckly yellowish white. Underneath, there are a couple of tiny tiny black things :(