Preventing Hollow Heart

By Heather Bryant, Regional Field Specialist, Food and Agriculture

This is the time of year when vegetable farmers start calling me because having finally caught up on their sleep after a busy season, they are turning their attention to planning ahead to prevent a reoccurrence of whatever last season’s nagging problem was.  I like this part of the job; the nagging problems always change so they’re a good puzzle, but unlike in the middle of the growing season, it’s not an emergency.

One of last year’s problems was hollow heart in potatoes.  If you grow them in your backyard, you’ve probably seen it.  The plants look fine, the potatoes look fine, you peel them and they’re still fine, but then you cut them open and there’s a hole and/or some brown discoloration inside.  If they’re from your garden you cut that part out and go on with your day, but if you paid money for the potato you feel slightly annoyed.  So does the farmer, because s/he wants you to come back next season.

So what is it?  First of all it’s not a disease; it doesn’t spread from potato to potato or get worse in storage.  It doesn’t impact the nutritional value of the potato.  It’s just an unsightly disorder caused by environmental conditions.  It’s actually two disorders, brown center which causes the discoloration and hollow heart which causes the hole.  Often you see the two disorders together, but sometimes you will see one without the other.

The environmental conditions that cause brown center and hollow heart are low soil temperatures (less than 56°F) for 5-8 days, wet soils, and dry soils.  These conditions stress the plants and the problem can be exacerbated by an abrupt change such as heavy rain that follows a dry period.  The plants first become susceptible when tuber initiation starts (when the plants flower) and continue to be susceptible as the tubers grow.  The earlier the stress occurs the more likely you are to see brown center, the later the stress the more likely you are to see hollow heart.  Larger, faster growing tubers are more susceptible than smaller, slower growing tubers.

The weather this past summer explains why hollow heart was one of the season’s nagging problems, but of course we can’t change the weather, so what can we do?  First, plant the potatoes at the tightest recommended spacing for that variety, or tighter than you planted them the year you had a problem.  8-12” apart in rows that are 36” apart is a good starting place, but write down what you do this year so that you can space them closer next year if you need to.  You also want the plants to have 3-4 stems when they emerge, so if you aren’t getting that, cut your seed pieces larger with more eyes.  If you plan to use fertilizer, consider splitting it into two or three applications rather than putting it all on at the beginning of the season.  This will encourage the plants to grow at a uniform rate.  As fall arrives the soil gets colder, so planting earlier varieties and harvesting earlier will minimize the risk.

I can hear it now, “but I like large potatoes for baking”.  Everyone always says that.  What can I say?  You could always leave a small section of your potato patch with wider spacing and smaller seed pieces so you get a few large ones for special occasions.

Source : unh.edu