Bitter Pit
Calcium-related physiological disorder
A common physiological disorder of apples, not caused by any germ, in which small sunken brown spots of dead, corky flesh form on and just under the skin. It is tied to a shortage of calcium in the fruit and is especially troublesome on prone varieties such as Honeycrisp, showing up late on the tree or after weeks in storage.
🔎 How to spot it
Affected apples develop small, slightly sunken dark spots, most numerous toward the blossom end, and under the skin the flesh beneath each spot is brown, dry, and corky and may taste bitter. The pits can appear before harvest or develop during the first month or two of cold storage, sometimes after the fruit looked perfect at picking. Cutting just under a spot reveals the dry, spongy dead tissue.
🥀 Damage it causes
The corky pits make the fruit unsightly and unpleasant to eat, downgrading the crop and shortening its storage life, since pitted areas break down further in storage. Large, low-crop trees often bear the most heavily pitted fruit. The disorder does not spread from fruit to fruit but can affect a large fraction of a susceptible variety in a bad year.
🔬 What causes it
Bitter pit is a physiological disorder linked to too little calcium reaching the fruit, rather than an infection. Calcium moves poorly into fruit and is pulled away by vigorous shoots and by large fruit on lightly cropped trees, and the problem is worsened by hot dry spells, uneven watering, heavy pruning, over-thinning, excess nitrogen and potassium, and anything that injures the trunk and disrupts calcium flow. Some varieties, notably Honeycrisp, are strongly predisposed.
🛡️ Prevent it
Aim for steady, moderate tree vigor and a good crop load rather than a few oversized fruit: avoid heavy dormant pruning and excessive nitrogen, do not over-thin prone varieties, and keep soil moisture even with consistent watering and mulch. Maintain proper soil pH and avoid excess potassium and magnesium, which compete with calcium. On chronically affected varieties, foliar calcium sprays through the growing season are the standard preventive.
🧯 If it is already here
There is no cure for fruit that is already pitted, so management is preventive over the season: multiple foliar sprays of calcium, usually calcium chloride or calcium nitrate, from early summer until close to harvest reduce the disorder on susceptible varieties. Combine sprays with steady water, balanced fertility, and sensible crop load. Use the most affected fruit first, since pitting worsens in storage.
💡 Good to know
Bitter pit is a nutrition and water-balance problem in the tree, not a disease you can spray a fungicide on, so the fixes are calcium, even watering, and balanced vigor. Honeycrisp is the poster child for it, and growers of that variety plan on calcium sprays every season. Because pits keep developing in the cooler, sell or eat susceptible, heavily set fruit early rather than storing it long.
🌱 Plants it affects
11 plants in the library can be affected by this problem
For educational and informational purposes only. Disease management advice is general guidance drawn from university cooperative extension sources; always identify a problem positively and read and follow the label on any product before use, especially around food crops, children, and pets.