1. Nematode Thresholds and Damage Levels for California Crops Howard Ferris and Philip Roberts Nematology Workgroup Meeting March, 2005

2. Sources of Data Ferris et al, 1970s and 1980s Roberts et al, 1980s Cooke and Thomason, 1970s Some Constraints to Early Adoption Availability of inexpensive nematicides Development of resistant varieties in some crops Publication of thresholds in arcane format

3. Some of those involved…. Dan Ball Larry Duncan Pete Goodell Joe Noling Diane Alston Sally Schneider Lance Beem

4. Thresholds by field plot South Coast Field Station USDA Shafter Tulelake

5. Thresholds by transect Imperial and Coachella Valleys Ventura County Tulare County

6. Seinhorst Damage Function Y=m+(1-m)z (P i -T) Y=relative yield m=minimum yield Z=regression parameter P i =population level T=tolerance level Based on preplant population levels – measured or predicted from overwinter survival rates

7. Case Study on Cotton CultivarSoilLocation(T)oleranceZm SJ2loamy sandsouth SJV650.9980.55 Deltapineloamy sandimperial500.99720.65 SJ2, SJ5, SJ-C1l. sand/s. loamsouth SJV550.9990.48 average (all)----------------------------------570.9980.56 average (SJV)----------------------------------600.99850.52 SJ2(-FOV)sandy loamsouth SJV550.99660.54 SJ2(+FOV)sandy loamsouth SJV550.98470.38

8. Meloidogyne incognita, J2/250 cc soil Expected % yield loss at different preplant nematode densities CultivarSoilLocationThreshold2050100200500 SJ2loamy sandsouth SJV2505152741 Deltapineloamy sandimperial1907162634 SJ2, SJ5, SJ-C1l. sand/s. loamsouth SJV2104101937 average (all)----------------------------------2206152740 average (SJV)----------------------------------2305122441 SJ2(-FOV)sandy loamsouth SJV21010233745 SJ2(+FOV)sandy loamsouth SJV210425962 Case Study on Cotton

9. Damage Function Parameters for Selected Crops Crop(T)oleranceZm Bell Pepper650.99780.87 Cantaloupe100.99720.40 Carrot00.990.6 Chile Pepper390.99340.70 Cotton57.50.99760.6 Cowpea220.98160.96 Potato180.990.49 Snapbean140.99780.57 Squash00.98980 Sugarbeet00.99550.89 Sweetpotato00.993750.47 Tomato41.80.999340.47

10. Thresholds and Expected Yield Loss Meloidogyne incognita, J2/250 cc soil; adjusted for extraction efficiency Expected % yield loss at different preplant nematode densities CropThreshold125102050100200 Bell Pepper2500000258 Cantaloupe400137173046 Carrot0125916293740 Chile Pepper1500003142430 Cotton220000061527 Cowpea5200000068 Potato7000415344751 Snapbean500013101829 Squash0351223417493100 Sugarbeet0001125810 Sweetpotato0124815304351 Tomato16000003714

11. Expected Damage Meloidogyne chitwoodi; summer crop potato; Klamath Basin Fall population levels; adjusted for extraction efficiency Expected % tuber blemish at different fall nematode densities J2/250 cc125102050100200500 % Blemish3457812151825

12. Thresholds and Expected Yield Loss CultivarSoilLocation(T)oleranceZm US-H9clayImperial1000.998860 US-H9loamSJV/Idaho3000.999760 Heterodera schachtii, eggs/100g soil Sugarbeets CultivarSoilLocationThreshold501002005001000 US-H9clayImperial10000113764 US-H9loamSJV/Idaho300000515 Expected % yield loss at different preplant nematode densities

13. Some 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 Systems 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. Agricultural, Ecosystems and Environment 12(1984/85):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. Carlson 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. Univ. of California Publ. No. 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. Univ. of California Special Publ. No. 3272. 32 pages.