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I currently live in southern Massachusetts. When an apple tree in my backyard blossoms and the little apples begin to show, they all disappear and begin to fall on the ground. FYI, there are also inch-worms all over the tree. Why is this happening? What can I do to prevent it?

EDIT:

The tree is about 6 years old and it has full sunlight, about 8 hours from morning (6 am) until late afternoon (4 PM). We have 3 of these trees and all these trees are in the same condition.

Pictures:

Full Image Full Tree Image

Image of leaves Picture of leaves

The result of some-type of insect (probably inchworms): enter image description here

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    How old is your tree? Do you know the variety? And are there other apple trees in the area? – michelle Jun 16 '14 at 3:52
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    Can you post pics of the worms, leaves, and maybe a shot of the entire tree? Also can you try to describe the location (amount of direct sun, level or sloping ground [and which way it's sloped], soil type, watering schedule, fertilizer applications, if any, etc.). Thanks! – J. Musser Jun 16 '14 at 4:10
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It appears that your apple trees are getting too much nitrogen. Apple trees always prioritize what to do with their available nutrients, and too much nitrogen causes them to abort fruit crops in order to put out new growth with the nitrogen excess. Also, the unbalance caused by the nitrogen excess makes the tree put most of the other available nutrients (Potassium, Phosphorus, and the micronutrients) into the new growth. This also discourages fruit.

I also noted that your trees have never been properly pruned. The tree is very dense in the center where all the fruiting spurs are. Apples don't like growing in the dark. If you don't feel confident pruning your tree, maybe you could consider hiring a professional.

Putting a mulch of high carbon material soaks up nitrogen, especially if it has lots of surface area (like sawdust). Keep in mind the acidifying nature of many of these materials. When you fertilize, use a no-nitrogen fertilizer, like 0-21-15, that has a lot of potassium in it.

If you prune it properly next winter, mulch, fertilize carefully, and keep an eye out for disease, you should meet with more success.

I see only minor damage from the inch-worms. You can spray with carbaryl if you think they will become an issue.

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