I have an unidentified pink flowering crabapple that gets fruit rot (both hard oxidized flesh & sunken black spots) and completely defoliates every year from what looks like black rot/frogeye spot, so there is plenty of inoculum here. The affected tree is also upwind of my apples so the fungus will be in contact with my trees.
Of my recent apple bench grafts three have been affected so far - Grimes Golden, Fuji Beni Shogun, and Winecrisp. Grimes got some spots on the first leaves but all new growth is clear. The Fuji OTOH continues to get the spots, but grows anyway. The Winecrisp hasn’t taken off yet so the jury is out, I’m leaning optimistic on it. Since they are benchgrafts I don’t have fruit to measure.
The following varieties have no spots on their leaves and all have taken off.
There are only a few apples I’ve owned that didn’t see black rot. Some are worse than others. Like fire blight, the condition becomes peskier after the tree starts fruiting.
Summer Rambo, Victoria Limbertwig, Winter Terry stand out as low on the rotting. Freedom, Va Beauty are epic rotters.
Oh so you’re saying the rootstock confers fungal resistance to the scion?
All my just planted apples are on Antonovka which I know was used for P18. I’ll be putting some more on M111, Bud 118 & M7. The M111 ones are for a friend.
Yes. P.18 is Antonovka x M.4. We are using P.18 this year as B118 could not cope with the heat here. Plus P.18 has very large roots and does well on sandy loam. No leaning issues.
It’s on my mental list to get some P18 in the future for stooling so this is interesting.
Anchorage is a little bit of a concern for me as well, mainly because of wind gusts that go through here in wintertime. I’m on a clay loam soil with excellent drainage due to the fractured schist rock underneath. This is why I went with Antonovka for my main trees.
Some people say that grafting can influence how genes in the different parts of the tree are expressed. It could also be that P18 is an excellent rootstock for @dannytoro1’s situation and that the trees themselves are just better equipped to handle the fungus just from that extra suitability.
I think P.18’s large root system influences nutritional intake that lessens the incidence of rot. I have read some EU reports where this happened with P.2 and some other P. Series we do not have here.
All P. Series were rigorously chosen and selected for Sandy Loams of Eastern Europe. So yes that means they have advantages with many of the problems found in that type of nutritional deficit soils. Prone to rots, cankers, mildew and nematodes. Silverleaf too.
They definitely are not perfect. WAA and Blight can get them. But I rate them as a step above Malling Merton. On par with Budgosky and below Geneva.
I just did a perplexity search on P18 and it’s suitability for the Deep South. I attached it here, I think arguing with AI is funny, because it is so amazingly intellectually flexible. On a second note, the app learned so much about me already from my searches (where I live, what model and year car I drive, what my hobbies are et cet et cet), that it gives me the creeps.
That is very interesting. I would note the USDA rates P.18 as moderately resistant to fireblight. Growers report it definitely ages into resistance like Antonovka. The fact it is resistant to rots, canker and mildews says it will handle “hot and humid” well.
