By Denbig
United Kingdom 
I planted three sorbus vilmorinii at the front of my bungalow three years ago. Two of the trees are developing strongly but the third is not so vigorous. Nevertheless all three produced a wonderful crop of pink berries last year. This year the weakest tree is flowering well, whilst the two stronger trees have yet to show any sign of flowering. Have you any explanation for the difference in behaviour? Is there any chance that the larger trees may yet produce flowers?
1 Jun, 2010
Answers
Thank you Fractal. Your answer to my question is extremely helpful and I am sure you have hit the nail on the head! It is quite probable that there is a variation in soil quality. My soil in some areas is almost solid clay.
2 Jun, 2010
Previous question
The larger more vigorous trees are making hay while they can as their roots must be in better soil. The third weaker tree is physiologically stressed and has turned completely to flowering.
Personally, I would prefer to have the former growing phase first as they will make fantastic flowering trees later, perhaps a year or two. The other may struggle in the long term unless it can get it's roots down into something better.
The other possibility is that their is another problem with the weaker tree causing the same effect. Check the graft point for any split or suckers coming from below the graft point. This could create the same effect.
1 Jun, 2010