Help w/ apple tree diagnosis

[giantsridge]

We have planted six apple trees over the course of several years, and they are about 7-9 feet tall. All of them looked fine as they budded this spring, but three of them have started dropping leaves and the bark is 'cracking' vertically, as shown in the attached photo. Please help!

 

[S Mc]

Could we get a photo of the entire tree to put this picture in perspective? How many trees are affected and how much of the tree(s) is affected?

What are the condition of the leaves prior to dropping? Are they brown, wilted, dry and crispy, etc. Is the damaged stem blackened? Does the tip bend over in a shepherd's crook?

Have you used any chemicals to control the grass or broad-leafed weeds in the vicinity of these trees?

What is the watering regimen like? Did you have any late, unusual freezes?

Any information like this would be helpful.
Sylvia

 

[giantsridge]

We have 6 apple trees, 3 of them have this condition. The others look completely fine. Also, two new plum trees planted this spring appear unaffected. All of the trees are in the same area of our field, spaced 50 feet apart from one another.

Attached are more photos which hopefully illustrate it better.

The affected trees have vertical 'cracking' along the trunk and/or branches, which may extend only a foot or as much as nearly the length of the tree. The base area seems to be the only place not affected on any of the trees. Where they have cracked, the bark appears darkened (like dark brown, but not black) and is starting to peel off in some places. The tips do not appear to bend over at all.

On affected areas, the leaves wilt, brown and fall off.

We have not used any chemical treatment on these trees. In the past, we have mulched around the bases with wood chips and/or lawn clippings. On the advice of a greenhouse, we purchased Jobe's fertilizer 'spikes' and put them in the ground (two per tree) this spring.

Other than the first few weeks after being planted, we do not water the trees other than rainwater.

We had several frosty mornings in late may/ early June, including one day that was 25 degrees F at dawn. However, for northern MN, this doesn't seem too unusual. I can't say for certain if the condition started before or after this hard frost, unfortunately.

Hopefully, this info is useful. Thanks for any help!
Shawn

 

[Urban Forester]

Your first picture appeared to be sunscald - warm days cause conductive tissue to move water, then cold nights freezes the cells causing expansion cracks. In the 2nd set the last one appears to be a more severe problem. This could be canker disease (vascular disease that entered "wounded tissue") or fireblight a bacterial infection. Here are some clues to look for. Canker disease will manifest itself as small black dots along the stem (woody) tissue. In late summer these dots turn orange (active period). It can also show up as discolored stem tissue, dark maroon, sometimes black in short 1 to 3" segments of stem tissue. Fireblight at the initial point of infection causes the terminal growth (out on the ends) to hook down (like a shepherds pole). The hooked area blackens in a short time and dies then "cankered areas" (see above, no "dots") appear at random points in the tree. This is where the infection now originates. Since both of these move through the vascular system and can move from tree to tree they need to be dealt with. "Long distance diagnosis" is throwing darts at a board, this problem may NOT be these issues and may be something simple. I would contact a Certified Arborist (through the ISA website) and have him take an up close look at these trees to determine what the problem is. Good Luck.