Hot weather peach grafting

Studying the results of my latest peach grafts done preceding +80 degree weather on Mem. day weekend, it seems those in relative shady locations did better than ones in full sun, suggesting that maybe a small improvised umbrella shading mid-day sun might improve the number of takes- something you might want to try when the weather turns unexpectedly hot after grafting peaches or if you procrastinated too long.

I was also delighted to see my first successful (or at least currently growing) persimmon grafts that I grafted on brand new shoots. Both grafts I made are growing. I haven’t checked the persimmon grafts I made onto older wood on the same day, but this was a Kaki tree frozen to the ground and I grafted Szukis, an American variety, to a couple suckers coming from the ground low enough so I can cover the union with dirt and protect it from freezing out again as it has done for the last two winters.

An orchard I manage has this variety and it is a semi-dwarf tree that produces a large crop of delicious, seedless, very sweet fruit every year- all by itself. It is Lee Reich’s favorite variety of American persimmon.

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Scott suggested something similar- wrap with aluminum foil, shiny side out. I did that on some of my peach grafts, but only after they took almost a day of hot temps, which may have been too much.

While my late peach results were extremely dismal, I used up some extra apple scionwood on 6/4 and got pretty good results. Some of them took some time to come out, but I’m well over 50% now.

PRI 1312-6 (15 brix, scab, PC, and apple maggot resistant) grafts. The one on the right is from 4/22 and the other 4 (one is opposite the camera and hard to see) were made on 6/4, with 3 takes.

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I think scion quality becomes an important factor during a heat wave. I grafted Harrow Diamond and Easternglo onto the same 4 trees just before a heatwave hit. I wrapped them with tinfoil. All of the Easternglo took, but all of the Harrow Diamond failed. I think the Harrow Diamond must have been too dehydrated from storage and handling.

It is difficult to tell quality of the scion when looking at them. You can tell their quality when at the extremes, but most of they time they are somewhere between.

In hot weather and/or late season grafting i increase the use of aluminium foil and the percentage of takes benefits a lot from its use. It prevents dehydration and the “hot greenhouse” effect that parafilm can have that can cook the graft.

Usually in the 3-4 week (depending on fruit type) i inspect them and when the buds break i open the foil a little so the sun may enter, but not directly (like an umbrella). After a week or two i remove it completely.

A few example photos…

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That foil looks really good. I also use foil on any later/warmer graft. This year I still failed on them, in retrospect I should have used more foil to cover more than just the graft itself and the scion. The more of the stock you are cooling the less heat will make it to the graft union. Also I used parafilm on the graft, I agree its not so good to use in the heat. I usually paint with Doc Farwells but was only doing a couple grafts and didn’t feel like dealing with the mess.

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I also think the scion quality and size has a lot to do with the success rate, especially with stone fruits. Thinner wood grafts much better. I’ve never used tin foil, but have had good results with paper bags

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I agree with Ray that scion quality makes a big difference. It’s just hard to keep peach scions dormant and in good shape.

I’ve been grafting Euro plums on peach rootstock for a while. The percentage takes is considerably better with plum on peach vs. Peach on peach. It’s my theory the rootstock does the callusing since that’s mostly where the energy comes during initial growth.

Imo, the best explanation for better E. plum success is that the scions are in much better shape. E. plum scions come out of the fridge looking like apple scions.

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An alternative i am using to aluminium foil is paper bags, like Ray is suggesting, but for most grafts the aluminium foil is simpler to use. I am reusing the cushioned envelopes i receive with scions exchanges. They have a plastic interior and every graft i did using this method is developing nicely even in hot weather. I still use parafilm on the scion, so the buds stay protected against dehydration when i open the bag.

I feel that either method is important because it gives the graft enough time to begin growing without being scorched by the sun (last year i lost several that had taken but didn’t resist the heat they received the first few days after breaking buds)

Both methods have improved the success rate of late grafts in hot weather especially in figs where i am doing whip and tongue in July with success when i used to stop doing it in April/May.

Figs

Pistachio

Apple

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You are so right. Scion shape of peach scions is the reason most fail in my book. Thinner (younger) wood may help in some cases, like Ray says, but the problem, to me, is that peach scion keep badly in the fridge compared to other fruit types.

Last year i received some peach scions where the buds were blooming or falling off before i had a chance to graft them.
By miracle some resisted and took, like the one in the next 2 photos. The scion had a single viable bud near the base (all the others had fallen). I was amazed how lucky i was that it was successful.

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Ray, do you understand the difference between a bark or chip graft and a splice graft?. With a splice you are grafting onto a shoot of the same diameter (when possible) as the scion. A thin piece in this method just makes matching the cambiums that much harder and probably provides less energy reserves as well. Also a thicker shoot you are grafting to means greater access to water and nutrients via the vascular sheaf. Thinner wood works best for your specific method, but not for all methods. I use a splice because it is the quickest technique for me and pretty reliable, although I’m still learning about peaches.

Jsac, thanks for the suggestion that parafilm may be encouraging the cooking of the scion. That was never a problem with early spring grafts but I believe it may be with my later peach grafts.

Alan,
I perfectly understand the differences, and I’m relating my experiences
with the type of grafting I do. I don’t do chip grafting, nor do I care to learn.
I know what does and doesn’t work for me, and I consider myself a proficient grafter in my methodology.

Without a qualifier of the kind of grafting you are doing you could easily leave the wrong impression to someone who doesn’t use your specific technique. I just want to keep things clear for anyone who might be trying to figure out grafting. Graft failures are extremely frustrating.

I’ve stated a number of times in other grafting threads on this forum,
the type of grafting that I do, and the reasons why. I see no reason to
continually repeat myself. But, for your benefit, I bark and wedge graft.
That’s all I care to do.

Jaimie, I too have received similar peach scion wood, but I’ve never had
your success. I believe a lot has to do with when the wood was cut. Too many
people wait too close to bud break to cut scion wood. It’s virtually impossible to wrap that type of scion wood in Parafilm, without destroying the buds.
In those instances, I forego the parafilm and simply place a vented plastic
bag over the entire graft, in order to prevent the graft from drying out.

You have nailed it, Ray. Many people cut their peach scions too late. The buds fall on the journey or on the fridge.

When i see those type of scions i don’t even think about wrapping them in parafilm. I protect them some other way, like you, usually with aluminium film or a paper bag (a bread bag is the best, because has paper on one side and a vented plastic slot microperforated on the other that is great to see when the buds break).

Here’s one, in a fig graft:

Are there cases where aluminum foil can retard the take of a graft because maybe some grafts like the heat not necessarily brutal heat but just not the shade provided by aluminum foil?
I have aluminum foil on paw paw grafts and I’m wondering if I should remove the foil if temperatures are moderate say 60 to 75

I have removed it on occasion, but it was when it was 50F and sunny and I wanted some more warmth on the grafts. 60-75F is fine for callousing, I would just keep it on with that.