[omits]

When my plums are going from green to yellow end rot sets in. The soil is kept damp and I feed with the occasional chicken manure and water with rainwater. I have used beetroot water earlier but other plants there are OK.

Any advice welcome before I remove the plant. Thanks.

[mumofstig]

It's caused by calcium deficiency, which is usually caused by the roots getting too dry between waterings. On a really hot day, they're better with a morning and evening watering, rather than one big soaking, as, If your plant’s roots get waterlogged, that may also stop the plant drawing calcium up to the fruit.
 
High Nitrogen fertilizer (like chicken manure) can also make the problem worse, try a proper tomato fertilizer (Poundland sell the cheap and cheerful Doff brand if you have one of those shops nearby - it may be cheap but it still works, I find)

They often just grow out of it anyway, once you've removed the first bad fruits, especially if the weather changes, so don't give up hope

[omits]

It's caused by calcium deficiency, which is usually caused by the roots getting too dry between waterings. On a really hot day, they're better with a morning and evening watering, rather than one big soaking, as, If your plant’s roots get waterlogged, that may also stop the plant drawing calcium up to the fruit.
 
High Nitrogen fertilizer (like chicken manure) can also make the problem worse, try a proper tomato fertilizer (Poundland sell the cheap and cheerful Doff brand if you have one of those shops nearby - it may be cheap but it still works, I find)

They often just grow out of it anyway, once you've removed the first bad fruits, especially if the weather changes, so don't give up hope

Great thanks, I'll pop in there and get some. The other tom plant seems OK except the skins are splitting on some.

edit to clarify quote

[Hortic]

Not only the blossom end rot but the splitting skins show a watering problem.