Tomatoes and cucumbers

I’ve heard people say you shouldn’t grow them together in a greenhouse is this right and if so why? 

BtB

I plant my Cucumbers at the far end of the greenhouse,, and the Tomatoes nearer the door. I have known people hang a plastic sheet to divide the two. Perhaps putting a gravel tray near the Cucumbers and keep it topped up with water - so it evaporates creating a more humid atmosphere.

ive grow toms and cucs together for 5 yrs , 3 cuc plants across the back of my greenhouses (3)away from the entrance,(telegraph cucumbers),

when they reach a foot high i lay a bucket of horse manure around the roots and water and feed them through the horse manure,

make sure you tend to the cucs 1st as you could pass on something if you tend your toms 1st ,