Q What’s wrong with my maincrop ‘Desiree’ potatoes?
A PIPPA SAYS They appear to have been infected with common scab, which is caused by streptomyces scabies. This problem tends to worsen in light, sandy soils that are low in organic matter or haven’t been cultivated for long. I got it badly for the first couple of years after turning a bit of rough grass into a veg plot. This common scab is also more likely if your soil is alkaline or has been limed recently. The good thing is that the damage is rarely more than skin deep, at worst causing slight discolouration of the flesh just beneath the scabby areas. It is fine to eat the infected tubers. There are no controls as such, but I’d advise adding more organic matter to the soil and increasing the acidity if the soil is naturally alkaline. Also, avoid planting tubers into recently limed soil and ensure that the crop is kept well watered. These steps should help to reduce the problem next year, as you’ll be providing conditions that scab dislikes.
This scab-infected potato may look unappetising but it is edible