1. Nematode Thresholds and Damage Levels for California Crops Howard Ferris

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

3. That initial population at which the difference in crop value with and without management is equal to the cost of the management The Economic Threshold amended Most nematode management decisions made before planting Pest population already present Pest population measurable Growing conditions are stable – temperature, moisture – time of planting Nematode population dynamics should be stable Damage should be predictable Premises:

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. Economic Threshold – Discrete Costs Model

7. Optimization – Continuous Costs Model

8. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. temporal avoidance

16. 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 Data from P.A. Roberts

17. Optimized Discrete Model

18. 0 200 400 600 800 1000 1200 1400 1600 012345678 Years After Planting Host Crop Pi(t+x)

21. Perennial Crop Considerations

23. Year 1 0 20 40 60 80 100 0100020003000 DD AUC LU LT NU NT Year 2 0 2000 4000 6000 8000 10000 12000 0100020003000 DD AUC LU LT NU NT Year 3 0 5000 10000 15000 20000 25000 30000 0100020003000 DD AUC LU LT NU NT

24. 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.