Managing bitter pit economically

Results of a field trial in Italy (2024)

Bitter pit

Bitter pit is a calcium-related disorder that hits apples hard. It shows up as small, sunken brown spots near the calyx end. Not caused by pests or bruising, but by poor calcium distribution inside the fruit.

Once bitter pit appears, the damage is done. The fruit loses quality, shelf life, and market value. And yes — that’s money lost.

Apple fruits severely affected by calcium deficiency

The root cause?

Calcium imbalance. That’s where POLY4 comes in. By improving nutrient balance and supporting calcium uptake, POLY4 helps reduce bitter pit risk leading to stronger fruit and fewer losses.

While other solutions for bitter pit - like foliar calcium or fertigation - are often expensive, water-dependent, and tricky to manage, POLY4 offers a simpler path.

It delivers calcium as part of a balanced nutrient package, without the extra cost, complexity, or irrigation demands. And for tree crops, where overapplication of water is often not desired, that’s a major advantage.

Evidence that backs the promise

In the 2024 harvest, Red Delicious apples grown in Trento province were part of a field trial comparing fertilisation strategies.

The goal: reduce bitter pit incidence through better calcium delivery.

The result: POLY4 programme led to significant reduction in bitter pit incidence, with similar efficacy to more expensive and cumbersome treatments with foliar and fertigation calcium.

Result of a field trial in Trento province, apple variety Red delicious, harvest 2024. Letters on the columns indicate significant difference (ANOVA and Tukey’s HSD test).

POLY4® is a trademark of Anglo American Woodsmith Limited.

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