Skinning

• Symptoms

Scratches, abrasions and peel damage are examples of superficial damage involving a partial loss of skin (exfoliation) on the surface of the tuber. Under the effect of enzymatic browning, this may cause the formation of rust-brown areas likely to seriously spoil the visual aspect of the tuber (photos 1 to 4). This may also result in significant weight losses during storage and increase the risk of burns caused by the use of sprouting inhibitors in storage.

• Risk factors

Skinning are typical signs of tubers that have been lifted before complete maturity. They are observed chiefly on early tubers, on seed potatoes or ware potatoes whose skin is insufficiently suberised, e.g. haulms destroyed prematurely, too short a retention time in the soil and excessive nitrogen fertilisation.

• Control measures

Preferably, harvesting must be done when the tubers have had sufficient maturation time in the soil to have a well suberised skin. At the same time, it is necessary to avoid too dry conditions. 

During harvesting, the settings must be very accurately adjusted: chain rotation speed consistent with the engine speed (ideally, a ratio of 0.8 to 1.2), minimum shaking, minimum aggression by devices used for the elimination of haulms and clods.