Symptoms

During the growing period, the presence of potato cyst nematodes in a field may be noticeable by the presence of patches (roughly circular foci) of poor vegetation (photo 1). Yield loss is rather proportional to the level of soil infestation and in sandy soil, it can reach 50%. However, very frequently adequate fertilizing regimes may often conceal the problem.

Fine examination of the root system of lifted plants at tuber formation (photo 2) may reveal the presence of white or yellow globes, i.e. females (photos 3 and 4) and brown cysts (photo 5).

In the case of very high potato cyst nematode densities, direct damage resulting from bites of nematodes can be observed on the tubers, in the form of small superficial tiny brown necrotic spots (photo 6).

When the presence of potato cyst nematodes is suspected, the analysis of soil samples is the most reliable form of diagnosis providing the soil sampling method is done thoroughly.