Honey Crisp

Asked September 7, 2018, 5:48 PM EDT

Can you please tell me what is wrong with my honey crisp tree? And what to do to help it? Photos attatched. Thank you. Rodney Schulz.

Hennepin County Minnesota

1 Response

The apples have apple maggot damage. Apple maggot flies lay eggs in apples in late June / early July in MN. The eggs hatch into larvae that create tan colored lines from tunneling inside the apples. The bumpiness of the apples and distorted form are caused by this larvae damage. More about apple maggots (and other apple pests) and how to manage them: https://extension.umn.edu/find-plants/fruit#apples--36410

The leaf damage in indicative of Japanese beetle feeding. This is usually more cosmetic damage than actually damaging to the tree provided the tree is healthy overall. More on Japanese beetles: http://blog-yard-garden-news.extension.umn.edu/2018/08/podcast-how-much-do-we-know-about.html

My biggest concern is the incredibly poor form of your tree. From the picture, I see you have planted the tree directly into lawn, pruned it on primarily on one side, and possibly staked it for several years creating a weakened tree structure. If you didn't stake it, it may be that you have not been pruning it annually (late winter) or correctly for best plant health, form and productivity.

Lawn grass will compete with trees and shrubs for moisture and nutrients, so we recommend removing the grass and weeds from the root zone of the tree about 6-feet in diameter, and mulching the root area of the tree with a circle of shredded wood mulch about 3" deep. Do not pile the mulch up around the trunk of the tree, but pull it back away from the trunk to the point you can see the root flare. Piling mulch against tree trunks can cause trunk decay and stem circling roots to form.

Planting directly into lawn also means you have to mow around the tree trunk and trim using a weed whip. Both of these activities can cause mechanical damage to the trunk by banging the equipment into the tree trunk (inadvertently). Damage like this - and it is visible on your honeycrisp - will create wounds which can provide openings for bacteria, fungi and insects to enter the tree trunk an cause further damage and disease. Unfortunately, there is nothing you can do about this damage once it occurs.

Pruning: From what I can see in your picture, your tree has been pruned primarily on one side, creating weight on the other side of the tree. If you staked the tree after planting for longer that a year, it can cause the tree to develop a weak structure so that it cannot stand up straight after the stakes are removed. Trees build trunk girth and strength by moving freely in the wind. At this point, you can try to do restorative pruning to encourage a stronger plant, but there's no guarantee your tree will ever stand straight and tall. Here is a video series about pruning apple trees that I think you find helpful: http://blog-yard-garden-news.extension.umn.edu/2018/03/how-to-prune-apple-trees-3-part-video.html

Apple tree require pest management, annual pruning and good health to produce apples. Please read and watch the Extension materials, and feel free to reply with more questions. We are always happy to help!