Garden Pests Series: B…

Thoughts and musings

Garden Pests Series: B…

Lewis | March 27, 2015 | 0 Comments

…is for Bitter Pit.

In the second blog post of our new Garden Pests Series, we will be discussed the disorder suffered by apples called bitter pit. In the series itself, we have selected 26 garden-somethings, each corresponding to the different letters of the alphabet, that can negate your gardening efforts. Some are more common knowledge than others, and others may even surprise you that it can affect your garden. The odd one or two may seem like we are ‘clutching at straws’, if you will. But they still fall within the category to be included in this blog series, and be fair, try yourself to find one beginning with letters that are worth a lot of points in a game of Scrabble! Anyway, let’s continue, with the letter ‘B’.

Bitter pit, also known as ‘tree pit’ when it occurs on the tree and ‘storage pit’ when in storage, is a reasonably common disorder in apples. It is classified as a disorder, rather than a disease, as it has been shown to be non-pathological. Either way, it is an unwanted sight; dark, sunken pits will appear on the skin of the fruit, and can also be in the flesh. In more severe cases, brown areas of tissue will be in the flesh – I’ve always wondered what that was – and it results in an unpleasant and bitter taste, hence the name.

The timing of the disorder is usually during the Autumn, especially following a hot and dry Summer. Some types of apples are more susceptible to bitter pit than others; a few are even resistant to it. However, it is still a common problem for gardeners and growers alike, especially on young apple trees that have been fed nitrogenous fertilisers.

The disorder has been reviewed extensively across time, and the main causes of it are dry soil conditions, a low presence of calcium in the fruit or in the tree during fruit development, and an acidic pH level. Therefore, treatment for bitter pit is reasonable simple through good horticultural practice; the dry soil conditions can be combatted by regular and correct feeding and watering. This can be done using a combination of a balanced fertiliser that isn’t nitrogenous- or potassium-rich, and perhaps installing an irrigation system that allows a supply a water during dry conditions. Coupling the former with a mulch will also help maintain water in the soil around the tree.

Not only this, extensive research for years in numerous countries across the world have demonstrated that bitter pit levels can be controlled with calcium sprays, preferably calcium chloride or calcium carbonate. Also ensure that the pH levels in the soil around the tree aren’t too acidic. You want your soil pH to be more towards neutral; 6.5 is recommended.

We hope you enjoyed this article; quite a number of apple trees grow in this country’s private gardens, and if one of them is yours then it is best for you to know about bitter pit! The next in this series will be out soon; what will the letter ‘C’ stand for? Have a guess in the comment section below and see if you’re right!