Apples glassy on the inside: Are pests on the fruit tree to blame?

Freshly picked apples are flawless on the outside. When you take a hearty bite, you suddenly see that the apples are glassy on the inside. What does this mean?

You can find more advice on your productive plants in the garden in the "Garden design"section.

Despite their perfect external appearance, you may notice that the apples are glassy on the inside when you cut or bite into them. The flesh around the core is then somehow translucent or transparent and looks watery.

Such spots can be found especially in fruits of the varieties Alkmene, Boskoop, Cox Orange, Fuji, Gloster and Goldparmäne with a high sugar content.

There is often uncertainty at first sight. Is the apple already bad? Is a disease of the apple tree responsible?

You can now find out what glassiness in apples is, what causes it, whether glassy apples are still edible and how you can prevent it.

Contrary to what some may fear, the glassy patches are not caused by disease or pests.

Instead, the watery spots are a sign of a physiological disorder, i.e. a metabolic disorder. A high sugar content in the fruit causes fluid to accumulate in the spaces between the cells.

This metabolic disorder is caused by various unfavorable growing conditions, such as ...

• ... particularly high solar radiation and temperatures in very warm and sunny summer months,

• a calcium deficiency caused by prolonged heat or dry periods,

• an excessive supply of nutrients,

• excessive vegetative growth (i.e. leaves, roots and shoots) instead of a balanced relationship with generative growth (flowers and fruit) through radical pruning and the resulting new shoots.

Glazed apples are edible and can be eaten without worry. The taste is also not negatively affected by the sugar storage.

Nevertheless, it is advisable to store the affected fruit for about ten days after harvesting at temperatures of ten to 15 degrees before storing them. This allows the watery areas in the fruit flesh to recede.

The apples can then be stored for the coming months.

However, if more than a third of the apple is already affected by the glassiness, it should no longer be stored and should be eaten soon instead.

If you follow a few care instructions, you may be able to prevent glassiness in apples.

• Firstly, ensure a balanced supply of nutrients - with a focus on calcium in particular.

• Make sure to water the apple tree sufficiently, especially in dry periods, or protect it from drying out with a layer of mulch.

• Do not harvest the apples too early or too late.

• Opt for less susceptible, less sugary apple varieties such as "Idared" or "Jonathan" right from the start.

Conclusion

Glassiness in apples is not a warning sign of disease or pest infestation. If the apples are glassy on the inside, the cause is a metabolic disorder.

However, the fruit can still be eaten without compromising on taste, as it is merely an aesthetic flaw.