By Mark61
South Yorkshire,
United Kingdom 
Hi all just wondered if any one could explain as to why some of my tomatoes are doing this.I keep them in a greenhouse,it is only one plant out of three which is infected like this.Any help would be greatly appreciated.:))))
29 Jun, 2011
Answers
It looks like tomato blight to me, and if it is, ALL the plants will suffer the same, as it's very infectious! According to my book, you should ''spray with a copper-based fungicide, or one containing mancozeb, as soon as the first tomatoes have set, and then repeated according to the manufacturer's instructions.''
I've had this before, and once the tomatoes start to be affected, they're not really edible, as they don't ripen properly. Sorry for such bad news. Have a look on the web under 'tomato blight' and see if you can find out any more.
Annie (Cumbria)
29 Jun, 2011
Could be blossom end rot due to irregular watering. You shouldn't have to pull out the plants just take off the rotton fruit and keep plants well watered.
29 Jun, 2011