Ditylenchus destructor Potato rot nematode Damage to Potatoes.   Presence of the potato rot nematode potato growing areas preclude the export of potatoes to international markets due to the restrictions imposed by many countries against this pest. Biology   Ditylenchus destructor   Ecology Symptoms.  No symptoms are visible during the growth period. Lesions appear on the tuber as small brown blemishes, the underlying tissues appearing granular and spongy.  General rot may also occur.  Damage to other crops Control