Assessment of the losses caused to potatoes by the potato cyst nematodes, Globodera rostochiensis and G. pallida

Abstract

S U M M A R YNine field trials were carried out from 1967 to 1973 on sandy loam soils in Staffordshire and Worcestershire to study the relationship between potato yield and numbers of potato cyst nematodes (Globodera spp.).Three (probably five) of these trial sites appeared to be infested with G. rostochiensis only, whereas both species occurred on the remaining four sites which grew the resistant variety, Maris Piper. Although mixtures of the two species occurred on some plots they tended to have different distributions within each trial site.The results from this work have been analysed, together with those from earlier work in the Eastern Counties on peat and silt soils, over two population density ranges, 0-40 eggslg (5 sites) and 0-160 eggs/g (16 sites). There is no evidence of any difference in the regression of yield on eggslg amongst the five sites in the lower range (b = -0.90 +_ 0.11) nor amongst 15 of the 16 sites in the higher range (b = -0.40 +_ 0-02). Analysis of 10 sites with sufficient data in the 40-160 eggslg range gave b = -0.24 k 0.06. Thus the regression lines are essentially parallel for each of the two ranges, covering several potato varieties, soil textures and different potential yields and suggest that the varieties used are equally tolerant. The losses are 6.25 tfhaf20 eggsfg for the 0-40 eggslg range, 1.67 tlhaf20 eggslg for the 40-160 eggslg range, and 2.75 t/ha/20 eggslg as a mean for the whole range. A maximum loss of 22 t/ha is indicated.Peat soils are less dense than mineral soils but there was no need for adjustment in nematode counts. Losses caused by potato cyst nematodes are better expressed as actual yield losses rather than as percentage decreases.

A review of tolerance by potato plants of cyst nematode attack, with consideration of what factors may confer tolerance and methods of assaying and improving it in crops

“…there is no necessity to determine T, z and m. In fact, the accuracy of Brown's equation was improved by Brown & Sykes (1983) who produced average yield loss figures of 6.25 t/ha/20 eggs/g for population densities between 0 and 40 eggs/g, with 1.67 t/ha/20 eggs/g yield loss in the 40 -160 eggs/g range. Unfortunately, easy as they are to use, the regressions proposed by Brown (1983) and Brown & Sykes (1983) do not concede that cultivars differ in their reaction to nematode attack, i.e. in their tolerance.…”

Field trials using single potato plants as whole plots, with and without nematicide treatment, to assess tolerance of attack by Globodera rostochiensis

“…Brown (1969) showed that, once nematode density exceeded a critical threshold, a yield loss of 0.85 tons/acre could be expected for each 20 eggs/g of soil of the nematode. Brown & Sykes (1983) revised this figure to 6.25 t/ha/20 eggs/g for population densities between 0 and 40 eggs/g and 1.67 t/ha/20 eggs/g in the 40-160 eggs/g range. Brown (1983) found that there was much variation from these figures between trials and attributed the variation to cultivar, seasonal or environmental influences.…”

Scientific Opinion on the risks to plant health posed by European versus non-European populations of the potato cyst nematodesGlobodera pallidaandGlobodera rostochiensis

“…Brown and Sykes, 1983;Trudgill, 1986). Yield losses of potato in excess of 50 % due to PCN are widely reported in the literature (e.g.…”

“…Yield losses of potato in excess of 50 % due to PCN are widely reported in the literature (e.g. Brown and Sykes, 1983;Trudgill, 1986). Yield loss is related to the level of nematode infestation, with crop damage increasing with higher nematode levels (Seinhorst, 1965(Seinhorst, , 1982.…”