Gardening for Life: How to avoid potato scab in the garden

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By: Jim Carpenter

16:9clue/Flickr Creative Commons

As much as I like to grow potatoes and as much as I think I do a pretty good job in my efforts, I have still had some problems through the years. Of course, this is pretty much par for the course in most any endeavor we strive for in life. Even in the things we are good at, even in our successes in life, there are still some struggles along the way.

A problem I have had with potatoes has been scab. Potato scab causes a warty, scaly growth on the skin of the tuber. It is caused by an organism that lives in the soil. While it won’t make you sick or cause any other harm if you would happen to eat it, it is still something you want to cut off. This is not a big deal in many cases as perhaps there is just a small spot or two on a large potato. However, since the infectious organism that causes scab will live in the soil for several years, it is very important that you rotate your potatoes.

Herein lies the rub. I like to plant my garden in what some might call a haphazard fashion. I will use some long straight rows on occasion but I like to kind of chop it up a little. I end up having potatoes planted in three or four different places in my garden. I try to allow two years before I plant potatoes in the same dirt again to lessen the buildup of scab in that area.

I had a horticultural judge tell me once if you put a bit of sulfur in with each potato you plant, you will not have scab. That will lower the pH of the soil to a point where scab cannot survive. But rotation works pretty well for me and I usually don’t have too much a a scab problem, however…

Even in the things we are good at, even in our successes in life, there are still some struggles along the way.

Because of the way I plant, one year I lost track of just where I had planted my spuds the year before and I planted a row over, pretty much the same area as the year before. This resulted in an entire crop of the worst looking potatoes I have ever seen. All of the potatoes were covered with scab. When I harvested them, I tried to hold out the slightly less affected ones until I realized that after cutting away the scabby areas, I would basically have about a french fry worth of potato left. Fortunately, I still got quite a few potatoes from the other patches I had planted in other areas of the garden.

There are other ways to minimize any scab problems with potatoes but rotating all your crops every year is very important in maintaining a healthy garden. Just as with the potato scab, there are many other organisms that will stay in the soil over time if they continue to get fed by planting the same crops every year that they depend on to survive. Insect larvae also will remain in the soil where their favorite crops are. By rotating every year, you greatly reduce many of the pests that come from the ground.

Another reason for rotation concerns the specific nutrients a particular crop needs. By moving different vegetables around in your garden, you allow the nutrients needed for specific crops to replenish themselves. Also, when you plant legumes (like peas and beans), you actually will make more usable nitrogen for the crop next year. 

Rotation is just one more tool you can use in your garden to help achieve the results you are after. Anything you can do to help create healthy soil is a very good thing. After all, it is the soil that ultimately makes or breaks a harvest, no matter how you fertilize or use chemical controls. All growing things will benefit from practices that improve the soil. Organic mulches, cover crops and rotation are some garden practices that can only improve the health of your garden.

I still battle at least a few potato bugs each year. But I can pick them off or if they get ahead of me, I might use an organic pesticide on them. But the harmful critters that live in the soil are a little more difficult deal with. So I will continue to try to minimize those problems with some basic common sense gardening practices. Rotation is one of the easiest ways to help produce a healthy harvest. That is, if you remember where and what you planted the year before!

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