Apple Pest Identification

Asked September 20, 2018, 3:24 PM EDT

The apple variety is Honey Crisp. I have two trees one in the back yard and one in the front yard. Both of these and other apple varieties were on a spray schedule using Spinosad and Horticultural Oil. The Honey Crisp in the back yard is the only one with the issue. My initial thought was Apple Maggott but I see no trails of any significance. I will not claim to have anything close to an educated eye for this purpose. The infected apples are all impacted to some degree from the blossom. With a big knife and severing the bottom third (nominal) of an apple and then looking in the saved two thirds for any signs there doesn't seem to be any spotting (occasionally the first third should have been half). I have included three images. The first image (Apple Problem_1.jpg ) is an external view of an infected apple. Many have the spots further up the side . The second image (Apple Problem_2.jpg) is from the blossom end with a thin slice taken off. The cut went through a spot at the nominal 1 o'clock position and you can see no trail from the external spot. The third image (Apple Problem _3.jpg) is another view from the blossom end with an additional slice removed. As I indicated I'm puzzled because of no apparent trail (Apple Maggot) and further confounded because the same variety in the front yard doesn't seem to have the problem. Several other varities in the yard also do not seem to have the problem.

Washington County Oregon insect issues apples fruit trees abiotic issues

1 Response

Your apples do not have any issues with insects.

The little depressed, dry spots were caused by a physiological problem called bitter pit. The cells die in those small areas because insufficient water was available to transport calcium to those cells.

Bitter pit may be visible while the fruit is on the tree. Other times, it shows up only after the fruit has been stored for aawhile.

Hot, dry weather in July or August tends to increase the incidence of bitter pit. Irregular irrigation (uneven soil moisture) may also increase bitter pit.

Other factors include the following:
Heavy dormant-season pruning, excessive fruit thinning (removal early in the season) and excessive nitrogen fertilizer promote bitter pit. Injury to trunks, such as winter freezes, interferes with calcium movement. Bitter pit occurs most severely in years of light crops.

Unfortunately, Honeycrisp is very susceptible to bitter pit. Even so, the problem is not guaranteed to occur every year. And when it does occur, severity will vary from one year to the next.

Management for bitter pit for home-grown Honeycrisp includes the following:
- Maintain even soil moisture by irrigating every 3 to 4 weeks through our dry months. Water deeply (to 8 to 10 inches), mainly at the dripline.
- Add a 3- to 4-inch deep mulch of wood/bark chips, extending outward from 6 inches away from the trunk to the dripline.

"Training and Pruning Your Home Orchard" is also likely to be useful to you. (https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/pnw400.pdf)