Swollen lenticels

Tuesday 7th August 2012
A Barn Owl hunts at sunrise

I have swollen lenticels!
Sounds nasty doesn't it? Well here's the story.
When I started digging up my potatoes this year, many of them had broken out in white spots. Not something I'd seen before or that I could recall seeing in the books. The spots rubbed off when the spuds were scrubbed and did not seem to go beneath the surface, nor to affect the taste. Unfortunately they did make the potatoes look worse than they were and difficult to sell as new pots.



Swollen lenticels
Easily rub off, but make the spuds unmarketable.
Given the continued sodden soil,
I think they've also allowed a first point of entry for disease.

At first I had assumed these white spots to be some sort of mould, maybe linked with blight, perhaps the very first signs of the tubers being contaminated. But why had I not seen this in the books?
So I consulted the biggest book on Earth, the interweb. Searched for "white spots potatoes" and up came several discussion forum topics, eventually leading to swollen lenticels.

What's more, it's not as bad as it sounds.
With the soil being so wet this year, the poor spuds have been unable to breathe and their pores have become blocked up. Hence - swollen lenticels.


Courtesy of The University of Nebraska-Lincoln CropWatch website, some very useful information:

Tuber External Growth Defects: SWOLLEN LENTICELS

Lenticels are pores in the skin of tubers; botanically, they are stomates. They are involved in gas exchange of oxygen and carbon dioxide during respiration and photosynthesis. Besides giving an unmarketable appearance to the tuber, the major problem is that an entrance to pathogenic organisms, bacterial soft rot, pink rot and leak, is created.

Development and Appearance

Swollen or enlarged lenticels (water spot, water scab) develop when tissue below the lenticel swell and burst through the protective covering of the lenticel. This forms a corky mass around the lenticel. The disorder is somewhat reversible if the wet period is short.

Causation

This disorder is caused by exposure of the tuber to very wet conditions in the field or in storage. The swelling seems to be related to oxygen deprivation by the watery film covering the lenticel.

Susceptibility

All varieties are susceptible.

Cultural Practices

Avoid over-watering. Avoid harvesting low, swampy spots in the field. Pick fields with good drainage. Avoid condensation in storage. Keep storage well ventilated.

Fascinating stuff ... Well, it is if you've got a severe case of swollen lenticels!

 



Not the best shot, but I still had the camera set for snapping the sun.