rootstock on wet ground


5 year old buck +
came accross this snippet on g30 rootstock

G30 (semi-vigorous)Medium: 10ft - 12ft10ft-12ft apartBush
Large cordon
Small fan or EspalierG30 is an adaptable, precocious, and productive new rootstock. It produces a tree somewhat larger than M26, similar to M7, and much heavier-cropping than either. It has good fireblight resistance. G30 is very well anchored but nevertheless permanent staking or support is essential for trees on this rootstock, because of the weight of apples it can produce which on some varieties can over-stress the graft union. Probably the best rootstock of any size class if your ground is subject to flooding.
Is it hardy in Zones 3/4?
yep supposed to be very winer hardy
If they are worried about the graft union, would this be one of those trees that could just be grown out from the rootstock? I wonder if there is any info on drop times and apple size for the G30 rootstock trees, similar to the B118 rootstock trees in the other thread?
I seem to remember Ben Harper saying that Polish 18 (P18) rootstock might work well in moist soils also. I haven't seen exactly how hardy it is. It might be worth a look.

Dipper don't you have some of these?
I saw a link on the Rum River QDMA facebook page that dolgo does OK in wet ground. I have heard that from a board member of our MDHA chapter and decided to try some dolgo.

Lee-what compatibility issues did you have with dolgo?