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Fruit & Orchards

Horse tree and powdery mildew ?

14 years ago

I have two issues:

First is my Horse apple tree. I planted it in Nov 2007 along with 20 other trees, all from the same place. The Horse is on mm111. It received the same treatment as all other trees. In May it started to show signs of stress. It is now toast, I think. The first pic is the Horse next to a Smokehouse tree, Horse on right:

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Close-up of Horse:

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Second question, I noticed this white stuff around several areas on one of my grafts. Is it powdery mildew?

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Comments (6)

fruitnut Z7 4500ft SW TX
14 years ago
thomis: The white material is probably woolly apple aphid. See if you can find the purple aphids under the white waxy material.

My only thought right now on your Horse apple is that something might be girdling it. Check for something low on the trunk that is girdling the tree. It is unusual for a tree to look like yours. And your trees are very well cared for. Don't see how it could be anything else you are doing, or failing to do.

The Fruitnut
thomis
Original Author
14 years ago
Damn. You were right Fruitnut. I came home and peeled the plastic trunk protector off and this is what I found:

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I thought I'd covered all my bases. Do you think it was a vole? I don't know what I could have done different. I can't see any tunnels around the tree. I have 20 other trees out there, I can't let this happen to any others. Please advise.
Thomis
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jellyman
14 years ago
Thomis:

I am a little confused here. The first two pics in your original post are obviously apple trees, but the third, the one with the white material, looks to be another species. Almost looks like a fig from the appearance of the leaves. If I saw that on an apple tree, I might consider rosy apple aphid as the culprit, but rosies are not as common in the east as they are in the west. Whatever is on photo No. 3 could also be mealybugs or cottony cushion scale. Looks like a job for oil spray or something like that.

As for the Horse Apple, since you can see no obvious vole tunneling, I might suggest crown rot or collar rot. Crown rot shows up where the roots join the stem, while collar rot appears slightly further up on the trunk. Collar rot does occur where I live, and I lost a Grimes tree to it about 10 years ago. Whatever the case, that tree looks like it should come out.

Don Yellman, Great Falls, VA
thomis
Original Author
14 years ago
Hiya Jellyman,

The third photo in my original post is another Horse apple tree I grafted this past March. It is a one year whip at this point and some of the leaves are bug-eaten. It is indeed an apple so I'll go with mealybugs or cottony cushion scale. I'm only a couple hundred miles south of you in central NC, by the way.

I'm pretty bummed about pulling out the Horse. It was the first apple tree I planted when I started the orchard in Nov 2007. I'd really like to think it was collar rot just b/c maybe that was something I had no control over, whereas the voles I can do my best to prevent...

I wonder if the collar rot can spread to the other trees in the orchard?
jellyman
14 years ago
Thomis:

I've only had collar rot once in an orchard of over 30 apple trees, and it did not spread. The site is now occupied by another apple tree that is quite healthy. Control or prevention of this malady does seem problematic if not impossible, so it is fortunate that it is uncommon.

Your little grafted Horse apple threw me because of the apparent large size of the leaves. Could be the perspective of the photo. I don't see the scale insect infections on outdoor trees, but have seen it in the greenhouse. At least one very thorough oil spray in the dormant season helps to head off these sucking insects. I try to do two, the last just before bud break, but don't always make it. Oil spray has become quite expensive in the quantities I use it. I mix 5-6 ounces per gallon of standard Bonide paraffin-based oil spray, so a full gallon of oil barely covers the orchard for one application.

Don Yellman, Great Falls, VA
jean001
14 years ago
Not powdery mildew.

Instead woolly apple aphids, a pest which is tough to manage, in part, because it also feeds on roots.

See this from Ohio State
http://ohioline.osu.edu/hyg-fact/2000/2208.html

Here is a link that might be useful: woolly apple aphid & more

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