Cedar Apple Rust

We’ve had an extremely wet year.  All my Apple trees have some degree of CAR infection. My only Antonovka seedling is much worse than the others. I thought about taking it out. It’s looks awful. It was planted with a couple pounds of morel spawn in the hole around four years. If I take it out, I might at least get morels next year. I was thinking that cutting it down to the ground next spring and grafting a resistant variety onto it might be better?  Does Cedar Apple Rust do anything to the trunk or roots. Is it likely to kill a young tree?

I wouldn’t mind spraying it with organic fungicide next year. I don’t want a tree I have to spray over and over. I will probably spray the other trees next year. Does the disease come back every year?

Hi Ken,

Here is a Cornell readout on the lifecycle of CAR.  I don't spray my trees, but a local orchardist recommended sulfur (too late this year).  I have improved soil health and heavily pruned my trees to keep very open canopies.  This does not eradicate the disease, but it has reduced the symptoms.  If you have Cedars on your lot you

Can remove them and it can break the cycle.  The downside with this remedy is the spore can spread for miles so you can't remove distant trees.  I haven't noticed that CAR effects the wood or bark just the leaves and fruit.  It can affect the vigor of the tree due to leaf drop.   I was surprised to learn that CAR can't spread from apple tree to apple tree only back and forth between

Apple and cedar.   It is a strange beast with a peculiar life-cycle.  Regardless of what the literature says, I have this disease on my trees every year.

The one tree that get's CAR the worst looks better than it has ever looked this year (Esopus Spitsburg) this is from heavy, open canopy pruning and soil improvement.  I do not spray.   The least affected trees are red delicious (pollinator) and Liberties.  The Liberty is very resistant; the problem is it's a triploid and the pollinators.

Are not very resistant.   I have a bunch of Malus sieversii seedlings, and they are affected at different rates.  Some seedlings have CAR terrible, and some hardly have any.

CAR PDF

Hi Ken. Sorry to hear that your trees have been affected by CAR. As someone who has a newly established orchard and tons of cedars on my property, I'm afraid we will fall victim to CAR as well. Seems inevitable at this point.

Anyone know if fruits affected by the disease are still edible? Or it a cosmetic thing? Also, can the leaves still photosynthesize if they have rust spots or should they be removed or cut down and the root stock used instead like OP suggested?

Sorry I can't offer any advice but I'm in the same boat and following the thread. Good luck!

Apart from sulphur, I have heard aerated compost extract sprays for the whole tree being an effective prophylactic as well as treatment for affected trees.

I think there are a number of good management strategies. Removal of organisms that have no resistance is probably the best long-term strategy, as is removal of all cedar on the property, or at least all that can be managed that are generally upwind of the apple trees. To this I would add strategically placed windbreaks and barriers to physically block or trap windborne spore.

I didn't know that CAR was only transmissible back and forth, and not from apple to apple or cedar to cedar.

Honestly, I am allergic to apples, along with pears and all stone fruit (god I miss bing cherries, peaches, and plum butter SO MUCH!) so the only reason for me to plant them is for others, and so that my hyper-local honey will have those components in its allergenic profile, so it can hopefully desensitize me.

But I would be selecting scion wood for grafting from trees with really effective and proven immunity, or at least serious resistance. Better yet, rootstock with that resistance paired with resistant scionwood. Better even still, I would love to air-layer trees previously grafted with said resistant scionwood, such that the seedling produced is all that resistant material.

The best, obviously, is to start a multi-generational program of local apple improvement, but that's a tall order. A worthy goal, but I don't even know how one would start to approach such an undertaking. It's like its the type of thing that you need a really dedicated, giving community of knowledgeable, kind people to begin, sketch out, and motivate people through over the course of many years. It would be even better if such a kind, knowledgeable, giving community could be found online, where it could be of use to many, and where it could be the hub of a number of these projects in their own regional iterations.

I wonder where we could find such a community? Hmmm...

-CK

I found the cedar trees, about six mature trees two blocks away. I was hoping for a few scrubby trees on some vacant land nearby.

I think I’ll try grafting onto it next year after I cut it down.  I have one small tree that seems immune. Think it’s Candycrisp maybe Honeycrisp. It about drowned but no spots so far.  Maybe I’ll look for another type for variety.

I almost made a huge mistake and cut the Antonovka. Partially because I was hoping it would trigger some morels to come up since I’d planted them together. The Antonovka is now my healthiest apple. It recovered very quickly and has many healthy leaves now. My other trees lost almost all their leaves. A few healthy leaves have grown back now. One Winecrisp tree is actually blooming now because of the leaf loss. Another Winecrisp is out in an open area with more air circulation didn’t get as bad. I have another apple tree that almost died. I think it had more than one disease.

The sickest Winecrisp has about 5 big healthy root suckers. I’m thinking about grafting onto all of them, but only keeping the best. My grafting success rate hasn’t been great. I think I’ll leave the main tree a year or two. Does this sound like a good plan? I may try the sulphur for a year anyway.

Do any of the apple rootstocks produce apples that are good for eating or at least cooking?