Nematode Thresholds and Damage Levels
		compiled by H. Ferris and P. Roberts
		(hferris@ucdavis.edu; philip.roberts@ucr.edu)
Damage levels may increase substantially in the presence of root pathogens, arthropods, water and nutrient stress.
Meloidogyne incognita, J2/250 cc soil (adjusted for extraction efficacy)
		Expected % yield loss at preplant nematode densities
Crop	Threshold	1	2	5	10	20	50	100	200
Bell Pepper	25	0	0	0	0	0	2	5	8
Cantaloupe	4	0	0	1	3	7	17	30	46
Carrot	0	1	2	5	9	16	29	37	40
Chile Pepper	15	0	0	0	0	3	14	24	30
Cotton	22	0	0	0	0	0	6	15	27
Cowpea	52	0	0	0	0	0	0	6	8
Potato	7	0	0	0	4	15	34	47	51
Snapbean	5	0	0	0	1	3	10	18	29
Squash	0	3	5	12	23	41	74	93	100
Sugarbeet	0	0	0	1	1	2	5	8	10
Sweet Potato	0	1	2	4	8	15	30	43	51
Tomato	16	0	0	0	0	0	3	7	14
Meloidogyne chitwoodi; summer crop poato, Klamath Basin
		Expected % tuber blemish at different fall nematode densities
J2/250 cc		1	2	5	10	20	50	100	200	500
% Blemish		3	4	5	7	8	12	15	18	25
Heterodera schachtii, eggs/100 g soil; Sugarbeets
		Expected % yield loss at preplant nematode densities
Cultivar	Soil	Location		Threshold		50	100	200	500	1000
US-H9	clay	Imperial		100		0	0	11	37	64
US-H9	loam	SJV/Idaho		300		0	0	0	5	15
Selected References
Benedict, J.H., K.M. El-Zik, L.R. Oliver, P.A. Roberts, and L.T. Wilson 1989. Economic injury levels for cotton pests.
Chapter 6. In; Integrated Pest Management Syztems and Cotton Production. R.E. Frisbie, K.M. El-Zik, and L.T.
Wilson (eds.). John Wiley and Sons, New York. Pp. 121-153.
Cooke, D.A., and I.J. Thomason 1979. The relationship between population density of Heterodera schachtii, soil
temperature, and sugarbeet yields. Journal of Nematology 11:124-128.
Duncan, L.W., and H. Ferris 1983. Effects of Meloidogyne incognita on cotton and cowpeas in rotation. Proceedings
of the Beltwide Cotton Production Research Conference: 22-26.
Ferris, H. 1984. Probability range in damage predictions as related to sampling decisions. Journal of Nematology 16:
246-251.
Ferris, H. 1985. Population assessment and management strategies for plant-parasitic nematodes. Agriculture,
Ecosystems and Environment 12:285-299.
Ferris, H., D.A. Ball, L.W. Beem, and L.A. Gudmundson 1986. Using nematode count data in crop management
decisions. California Agriculture 40:12-14.
Ferris, H., H.L. Garlson, and B.B. Westerdahl 1994. Nematode population changes under crop rotation sequences:
consequences for potato production. Agronomy journal 86:340-348.
Ferris, H., P.B. Goodell, and M.V. McKenry 1981. Sampling for nematodes. California Agriculture 35:13-15.
Goodell, P.B., M.A. McClure, P.A. Roberts, and S.H. Thomas 1997. Nematodes. In: Integrated Pest Management for
Cotton in the Western Region of the United States. 2nd edition. University of California Publication N0 3305
Pp. 103-110.
Roberts, P.A. and G.D. Griffin 1994. The economic feasibility of management alternatives. In: Quantifying
Nematode Control. G.D. Griffin, and P.A. Roberts (eds.). Western Regional Research publication #149, Utah
State University Press, Logan, UT. Pp. 23-49.
Roberts, P.A., and I.J. Thomason 1981. Sugarbeet Pest Management: nematodes. University of California Special
Publication no. 3272. 32 pp.