Hollow heart

also called Brown center

A potato that looks perfect until you cut it and find a star-shaped cavity in the middle. Growth went too fast after a check, and the center could not keep up.

Disorder Disfiguring Doesn't spread

What you'll see

An irregular, star- or lens-shaped hollow in the center of the tuber, with clean white or tan walls.
A brown discolored center with no cavity yet, which is the earlier stage of the same thing.
No sign at all on the outside — the tuber is smooth, sound and often the biggest in the row.
Large tubers affected and small ones from the same plant clear.
The same problem in the largest fruit of a summer squash or a swede.

Why it happens

The center of a tuber has no vascular tissue of its own and grows by expansion. When a check — drought, cool weather, a gap in the water supply — is followed by a sudden burst of fast growth, the outside expands faster than the middle can fill, and the middle tears. Wide spacing produces fewer, larger tubers and makes it far more likely.

Irregular water, a cold or dry spell followed by heavy rain or irrigation, over-generous spacing, and light sandy soil. Large-tubered cultivars — Atlantic, Kennebec, Yukon Gold and similar — are far more prone.

Treating it

Nothing can be done to a tuber that has it. Cut the hollow part out and use the rest, which is perfectly sound.
Use affected potatoes first rather than storing them; the cavity can pick up a secondary rot in store.
Water the remaining crop steadily to stop the pattern repeating in the later tubers.
Grade the crop at lifting and set the very largest aside for immediate use.
Do not treat it as a disease; there is nothing to spray and nothing spreading.

Keeping it away

Water evenly and mulch so the crop never has a stop-start growth pattern.
Space seed potatoes a little closer, which gives more tubers of a moderate size.
Grow cultivars less prone to it where the problem recurs.
Avoid a heavy nitrogen feed mid-season, which drives exactly the growth surge that causes it.
Do not over-irrigate immediately after a dry spell; bring the soil back up gradually.

Who gets it

Potatoes above all; also swede, turnip, large summer squash and occasionally cabbage stems.