Curling Apple Leaves

riddleranchJuly 6, 2010

Each season, the leaves on my five year old Jonagold apple tree curl upward noticeably. I have a Fuji and a Gravenstein that display the same tendency, but to a lesser degree. The tree bears some fruit, but the quality could be better. Adjusting the water regimen doesn't affect the condition. I've also looked for signs of powdery mildew, but I don't see white patches on the upper surfaces of any of the leaves (and it's always been my understanding that the white fuzziness on the undersides of the leaves is normal).

Until just recently, I never sprayed the tree with anything. This season though, with all the late rains we received in Northern California, I believe the tree is suffering from a case of apple scab. For the first time, the fruit has black spots all over them. I applied my first treatment of Neem oil this past weekend. I will continue to apply Neem oil weekly for the next several weeks.

Assuming that the Neem oil treatments don't suddenly cure the curling problem, I am curious whether anyone has faced the condition before and found the key to remedying it?

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myk1(5 IL)

Aphids or hoppers are my curling problem. Spraying pesticide takes care of them.

    Bookmark   July 6, 2010 at 7:11PM
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Axel(12b/Sunset H2)

I live in California, and I've noticed the same thing, but for me it does seem to be related to water. The trees that are next to the lawn that gets a good dousing on a regular basis are all very healthy looking. Yet the leaves on my granny smith, away from the lawn where there is less water are curling.

My theory is that if an apple tree gets even just a little drought stress, the leaves will curl. They will NOT uncurl even if the tree suddenly has plenty of moisture and water again, but new leaves will not be curled, and most likely, the tree may even start blooming again.

If the tree ever gets even a little drought stress, the leaves curl.

    Bookmark   July 7, 2010 at 2:47PM
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Mykl, I'm sure there are some aphids and leaf hoppers because the tree is situated next to a vast area of mostly native vegetation, and I never spray pesticides. However, I don't ever find any when I examine the foliage closely. With virtually all the leaves curled, wouldn't you expect to see quite a few of the critters whenever you decide to look?

Axel's water theory is plausible, except with so much late season moisture in my area this year, everything else (including all of the native vegetation) is continuing to show strong new growth without any supplemental irrigation. It might be that the tree happens to be in a spot that drains particular fast, and where the subsoil holds alot less water than the other soil in the area. When you see the curling, water stress is what naturally comes to mind, but all of the other normal signs of water stress are missing. I grow wine grapes commercially, so I have some experience with water stress, particularly with vinifera. Perhaps there is some interplay going on with soil chemistry and soil moisture, rather than exclusively soil moisture.

I'll keep treating the tree with Neem Oil to counteract the apple scab and possible powdery mildew and critters. I'll make sure it gets plenty of water too. If the leaves don't relax after that, I'll test the subsoil Ph and send a subsoil sample off to the lab to check other aspects of soil chemistry. Maybe the curled leaves are the tree's way of telling me that something in the soil chemistry is way out of whack.

    Bookmark   July 7, 2010 at 4:18PM
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I have a 3rd leaf Jonagold that did the same thing last year which was dry but I irrigated and figured I messed up on not enough water. There are other 3rd leaf varieties on 3 sides of the tree and they never showed the upward curling last year. This year has been WET so I now know the curling this year is not a moisture issue and the tree has no disease problems; however, leafhoppers were present this year and last on all the trees and I have been too lazy to spray for them and have no other insect problems to date. Maybe Jonagold just likes to curl when the hoppers are infesting it, beats me, the other trees are just fine.

    Bookmark   July 7, 2010 at 9:47PM
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Michael, I agree, its not related to how much water the trees are getting. This year, none of the plants in my garden have experienced any water stress yet.

Also, of the three apple trees (all near each other), the Jonagold has the upward curling condition far worse. If it's leafhoppers though, they are doing their dirty work without leaving a trace. I can't see anything wrong with most of the curled leaves, except that they want to curl rather significantly. I don't know if it's a clue of any sort, but the leaves on the newest growth on the tree curl the worst. The leaves toward the base of most branches almost look normal. Go figure . . .

    Bookmark   July 18, 2010 at 10:25PM
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davidguss(6 Walla Walla, WA)

I see the same curling on my Jonagolds. The trees are over 10 years old and on 111 rootstock. I've seen this several years on the trees, but they always produce excellent apples.

    Bookmark   June 30, 2013 at 10:02PM
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I just came back from the local nursery. I have an apple tree ( Rising Sun Fuji) that all the leaves have curled. Their explanation was that the tree has TOO MUCH WATER not that it was or had been too dry. There is no leaf damage at all. All green and no issue on any of the leaves except for the Japanese beetle damage that just started this last week.

    Bookmark   July 19, 2014 at 3:55PM
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Too much water, not enough water. This sounds a little sketchy to me. The leaves on my Jonagold are also curling up. Looks to me like with all the different locations reporting the same thing this might be a normal occurrence for Jonagold. I sure hope so. Jonagold apple is high on my like list. What say you?

    Bookmark   July 20, 2014 at 5:00PM
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skyjs(z8 OR, USA)

According to Warren Marnhart in "Apples for the 21st Century", Jonagold prefers a cool, rainy mild climate like the PNW or England/Holland, while Gala prefers a dry hot climate like Eastern Washington. Could be a reaction to the climate.
John S

    Bookmark   July 20, 2014 at 7:20PM
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