Methods for Detection of Potato Cyst Nematodes1

Methods are reviewed for inspection of growing potato crops and of soil sampling for detection and estimation of potato cyst nematodes (Heterodera rostochiensis Woll. and H. pallida Stone). Modifications of the Dutch soil‐sampling method are now widely used in Europe, including U.K. The statistical principles of soil sampling for Heterodera cysts are discussed. It is concluded that the efficiency of the method for detection is best improved by increasing both the quantity of soil examined and the number of sampling points per area sampled; the quantity is the most important factor which determines the level of infestation that can be detected. The area represented by a standard sample should be the same as that for which a separate decision will be made; variations in this area are unimportant because in effect one is sampling from an infinite population. It is concluded also that effective systems of control on potato‐growing land, and removal of soil from exported plants and potatoes, offer better prospects than soil sampling for preventing transport of cysts; a combination of these methods provides the best safeguard, e.g. for seed potatoes.