[Kleftiwallah]

Good morning everyone,  so what is the cause of this line on this standard sized Brandywine tom' ?  Cheers,   Tony.

P.S. Just put this beastie to bed to change into a pupa.  It's a Eyed Hawkmoth caterpillar Smerinthus ocellata  I think!

[Goosegirl]

Could it be due to irregular watering or extreme temps from low to high that have affected the uptake of water by the plant?

[JayG]

It's called 'zippering', and like 'catfacing' is usually caused by unfavourable weather conditions at the time of pollination and/or fruit development.

I've seen it from time to time on most types of tomato, although strangely enough, hardly at all this year, which has not been perfect for tomatoes by any stretch of the imagination!

[Kleftiwallah]

Many thanks to both your answers but especially JayG

Cheers,  Tony.