Why do my apples have brown spots through and through? - Ask Extension
A few years ago, I sprayed my healthy apple tree with copper spray. Every year since, my apples have had brown spots through and through. Depicted her...
Knowledgebase
Why do my apples have brown spots through and through? #435069
Asked November 21, 2017, 1:23 PM EST
A few years ago, I sprayed my healthy apple tree with copper spray. Every year since, my apples have had brown spots through and through. Depicted here is a fresh picked and cut apple. The brown spots can be seen on the outside and go through the entire apple.
Lane County Oregon
Expert Response
Thanks for your question! First, the copper spray is purely circumstantial and would not result in these symptoms. These symptoms are characteristic of a physiological disorder called bitter pit, which is the result of a calcium deficiency. This may be the result of inadequate calcium in the soil. You could do a soil test, but if you haven't added lime in several years (or ever, which is commonly the case), it would be a good idea to add about 5 pounds per 100 square feet. Now is a great time to add lime, because the winter rains can help carry it into the soil. You can get powdered or prilled (pelletized) lime; prilled costs more but is much easier to spread.
If the pH is really low, it may take more than one application. You can get a cheap pH test kit at most garden centers. If the pH is much below 6.0, it might be good to plan on a second application of lime in late winter/early spring (March or thereabouts).
Bitter pit does not necessarily indicate low soil calcium, although consistent bitter pit for several years certainly points in that direction. Anything that results in excessive foliar growth can cause bitter pit, because calicum gets diverted to the foliar growth. Heavy pruning, excessive nitrogen fertilizer, and excessive irrigation all can lead to bitter pit. It is important to prune correctly and consistently from year to year so the trees don't experience a boom-and-bust cycle of heavy pruning in alternate years. Also, fruit thinning helps to balance the crop load, which can also affect the incidence of bitter pit.
Here is a link to more information about bitter pit...
https://pnwhandbooks.org/plantdisease/host-disease/apple-malus-spp-bitter-pit
If the pH is really low, it may take more than one application. You can get a cheap pH test kit at most garden centers. If the pH is much below 6.0, it might be good to plan on a second application of lime in late winter/early spring (March or thereabouts).
Bitter pit does not necessarily indicate low soil calcium, although consistent bitter pit for several years certainly points in that direction. Anything that results in excessive foliar growth can cause bitter pit, because calicum gets diverted to the foliar growth. Heavy pruning, excessive nitrogen fertilizer, and excessive irrigation all can lead to bitter pit. It is important to prune correctly and consistently from year to year so the trees don't experience a boom-and-bust cycle of heavy pruning in alternate years. Also, fruit thinning helps to balance the crop load, which can also affect the incidence of bitter pit.
Here is a link to more information about bitter pit...
https://pnwhandbooks.org/plantdisease/host-disease/apple-malus-spp-bitter-pit
