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Potato, reasons not to delay harvest

Dig them quick, or perhaps not

by : Nov 1, 2015

Harvesting is a delicate balance between leaving long enough for the skin to mature and late damage. A mature skin is good for long term storage, but various factors can damage the tubers in the soil if they are left too long. Here are some factors to monitor by sampling as the decision is made.


The population of voles is quite high in my garden ever since the owls reduced my population of cats to zero. As a result I am seeing a marked increase in physical damage by chewing on otherwise good tubers. Here is an example of the effect: Image of a potato showing chewing damage Note the extensive chewing rendering the tuber unmarketable, fit only for early processing or the discard pile.

The damage has quite dried out and hardened, indicating that the damage must have occurred after the tuber had reached full size, so late in the season but probably would be hard to prevent unless the potatoes were dug very early indeed.


Normally, due to the fact that my garden is surrounded by grassy areas which act as a playground for white grubs, I see white grubs in my potatoes from time to time. This year I found only one, and made the mistake of eating it (the potato, not the grub) before I could get a photo. I'm sure there will be other opportunities. The white grubs hollow out a cavity in the tuber, making it good only for kitchen or discard.


I know that various worms can be damaging to potatoes, but honestly I don't see any in my crops so I don't really have anything to offer on the matter. I think I had some way back in the distant past when I first started up my garden plot, but since then nothing. Maybe due to strict rotation.


Quack grass (couch grass, etc.) is a valuable weed but spreads by spear-pointed stolons which can easily pierce the skin of a potato tuber, penetrate into the body of the tuber and even pass right through and emerge out the other side. In this picture

Image of an otherwise healthy potato tuber showing a small hole at one end, note the hole on the right side of the tuber. It is about 3 mm. in diameter and penetrates about 1.5 cm. into the tuber. Extracting the stolon leaves a clean cylindrical hole. With luck the tuber is still worthy of use in the kitchen, but is probably unreliable for storage or market.

In my garden this happens particularly at the edge of the garden plot next to the paths which are quite nicely infested with quack grass which is wonderful, in its place, mowed, and discouraged from growing from path into garden.


Note the presence of sclerotia (black spots hard to wash off) on the skin of the tubers in both images above. These can be reduced by early harvesting, but are more a function of good rotation to prevent buildup of spores in the soil. These particular fungi don't affect the quality of the eating since they are purely surface effects, just the visual appeal, so I am not troubled by this level of spoilage. It's the fault of the soil, not my choice of seed potato or lack of rotation.

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