URGENT HELP REQUIRED!!

after checking my tomato plants yesterday i have become worried!

The top new leaf growth seem to be turning a yellowish colour and the actual plant is wilting, looks like it is dying for water but are watered regular, same thing seems to be happening with cucumbers!

Any suggestions as to what may be happening and what to do about it as it looks like we will lose them very soon if we dont do something!!

Watered regularly and yellow leaves might be case of over-watering -how often are you watering?-are they in pots, ground, growbags?,-inside or out?

They are in the green house in the ground, only seems to be the plants in the middle aswell, the two on each end seem to be fine??

forgot to add, my partner looks after them so assume he only waters them when required, from what i have noticed, he tends to do them roughly every 2 days or so dep on what the weather is like.

If they are growing in border soil has anything else been grown in that soil in the past?-cucumbers especially do not like it too wet and suffer from neck rot where the stem meets the soil

How tall are the plants, how long have they been in, and perhaps you could post a photo?

Will take some photos when i get home and post on, with the rest of info required.

Sounds like too much water to me. It would need to be pretty warm for toms in the ground to need water every two days. Heck, it's in the high 30s here, the toms are in full sun, and I don't water mine more than once a week. But very very deeply when I do water.