What Is Causing The Top Of My Greenhouse Tomato Plants To Wilt?

[Euniceadi]

Can anyone tell me please what is causing the top of my tomato plants to wilt? The varieties are Gardeners’ Delight and Moneymaker, nine plants in total and are in new grow bags, three plants to a bag in my greenhouse. (Two tomato plants of a different variety growing nearby in pots of other compost are not affected.) The lower parts of the affected plants have normal foliage but I see three green tomatoes are going brown underneath. I don’t think that can be attributed to blossom end rot, as the grow bags stand in trays which have not been allowed to dry out.
Any information or advice would be welcome. Thank you.

[malagabob]

White fly. Too much water??

[Euniceadi]

Thank you, Malagabob, but there are no white flies around and I don't think overwatering can be a problem, as I've never had this before and many people give their tomato plants a constant water supply.

[alavahalf]

Over watering or inconsistent watering will leave you a tomato that is likely to have too high a moisture content, or will split.
The brown end on the tomato is down to lack of calcium. Two years ago some of my toms suffered the same fate.
Personally I add two spoons of Epsom salts to a 2 gallon bucket of water and feed them that every 2 weeks throughout the growing season, had no end rot since.
Only feed your toms once a week with tomato feed.
Have had great success this year, brought home three and a half builders buckets full of them last week !

[Euniceadi]

Thanks for your suggestions, alavahalf; I’ll bear them in mind. The plants are still spindly at the top but the fruit are setting and filling out well and it looks like I’ll have a good crop, although nothing like yours!