Rootstocks

[Mell]

FB thought this might interest you NYSAES-Geneva Breeders Programs: Geneva 16 Apple Rootstock

[FB.]

Thanks, Mell.

Yes, I'd generally agree with what they say.

I would add that although they state MM111 to be prone to mildew, I don't find the ungrafted MM111 to be any more prone to mildew than other ungrafted rootstocks - and mildew is a serious problem here (many of the garden weeds die from powdery mildews in the summer).
I've found MM106 to be most prone to mildew when ungrafted (but not troublesome amounts).
Scions on M26 seem most prone to mildew - maybe a reflection of the weak roots ability to gather water in a poor dry soil.
I think that MM111 and M25 improve mildew resistance of the scion, but that may well be partly due to the powerful roots gathering water and nutrients better from a poor soil, rather than any anti-fungal-substance exchange between root and scion.

Regarding burr-knots: I find MM106 to be a very heavy producer of burr-knots (and canker infection of the burr-knots happens from time-to-time), while M26 and M9 don't produce many at all, but M25 and MM111 produce medium amounts.
However, on my trees, those trees producing the most burr-knots appear to be those that are in the very worst areas of my soil - almost as if the burr-knots are a desperate attempt at sending out roots anywhere and everywhere to try to find water.
In fact, my Egremont Russet (MM106) sends out burr-knots up its trunk ("own-root"!) - but the poor little thing has a hard life (it's about 5-6ft tall and 3-4ft wide after ten years).
I've also had Belle de Boskoop and Norfolk Beefing produce burr-knots on the scion part of the trunk *above* the rootstock, when they were dying from crown rot.

[FB.]

Addition, to add to the data sheet on MM111 that you linked to:

I'd also say that MM111's bud break tends to be slightly early to average, while leaf fall tends to be average to slightly late.

The same scion on different roots would probably have its spring bud break in the following order in my area:

MM106
MM111
M26
M9
M25

....and leaf fall in the following order:

M9
M26
MM111
MM106
M25

Just a rough guess though, as every season is different and I often have to grow the smaller rootstocks in different soils to the stronger ones.