Tomatoes Forming but not ripening
Having an unusual problem in my greenhouse (small, personal use only) with my tomatoes this year, my old reliable plant variety (a Cobra derivative) is not ripening fruit. Lots of green tomatoes on the plant, with plenty of healthy foliage and new flowers, but the fruit never ripens. Typically this variety will ripen fruit and continue to produce new fruit throughout the season. This year there are new flowers and fruit setting, but the older fruits just stay green.
There is one difference this year from past seasons: I grafted a couple of tomatoes onto commercial rootstock. I did this because I was seeing some disease problems with toms in the GH and thought that grafting onto resistant roots might help. And it may have, we are 60% of the way through the season and no signs of disease yet which is way better than last and previous years.
However both grafted tomatoes (this Cobra and a cherry) are growing way more leaves than usual and the cherry is producing somewhat fewer flowers and fruit than usual. I don't believe that I have increased the level of N over past years, but have not had the soil analyzed this year either. And we have had more rainy weather this summer than typical (although that only effects the amount of sun and temps in the GH).
I am just curious if anyone knows if one of the effects of grafting tomatoes onto commercial rootstock is a delay in the ripening of fruit? Any other things which might be causing this?