Economic Thresholds Crop Management Systems Introduction to Nemaplex Nematology 204 May 6, 2013 Howard Ferris Department of Entomology and Nematology University of California, Davis

Crop Yield in Relation to Nematode Population Density

Annual Crops Critical Point Models Premises: Target nematode population is resident Population can be measured with acceptable precision Population can be measured with acceptable speed Population increase is relatively slow Management alternatives require decision prior to planting Population must be measured prior to planting are these premises valid?

Some Constraints to Early Adoption 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

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

Thresholds by field plot South Coast Field Station USDA Shafter Tulelake

Thresholds by transect Imperial and Coachella Valleys Ventura County Tulare County

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

Case Study on Cotton Cultivar Soil Location (T)olerance Z m SJ2 loamy sand south SJV 65 0.998 0.55 Deltapine imperial 50 0.9972 0.65 SJ2, SJ5, SJ-C1 l. sand/s. loam 55 0.999 0.48 average (all) --------------------- ------------- 57 0.56 average (SJV) 60 0.9985 0.52 SJ2(-FOV) sandy loam 0.9966 0.54 SJ2(+FOV) 0.9847 0.38

Case Study on Cotton Meloidogyne incognita, J2/250 cc soil Expected % yield loss at different preplant nematode densities Cultivar Soil Location Threshold 20 50 100 200 500 SJ2 loamy sand south SJV 25 5 15 27 41 Deltapine imperial 19 7 16 26 34 SJ2, SJ5, SJ-C1 l. sand/s. loam 21 4 10 37 average (all) --------------------- ------------- 22 6 40 average (SJV) 23 12 24 SJ2(-FOV) sandy loam 45 SJ2(+FOV) 42 59 62

Damage Function Parameters for Selected Crops (T)olerance Z m Bell Pepper 65 0.9978 0.87 Cantaloupe 10 0.9972 0.40 Carrot 0.99 0.6 Chile Pepper 39 0.9934 0.70 Cotton 57.5 0.9976 Cowpea 22 0.9816 0.96 Potato 18 0.49 Snapbean 14 0.57 Squash 0.9898 Sugarbeet 0.9955 0.89 Sweetpotato 0.99375 0.47 Tomato 41.8 0.99934

Thresholds and Expected Yield Loss Meloidogyne incognita, J2/250 cc soil; adjusted for extraction efficiency Expected % yield loss at different preplant nematode densities Crop Threshold 1 2 5 10 20 50 100 200 Bell Pepper 25 8 Cantaloupe 4 3 7 17 30 46 Carrot 9 16 29 37 40 Chile Pepper 15 14 24 Cotton 22 6 27 Cowpea 52 Potato 34 47 51 Snapbean 18 Squash 12 23 41 74 93 Sugarbeet Sweetpotato 43 Tomato

Optimizing the Discrete Model for a multi-year cropping system

200 400 600 800 1000 1200 1400 1600 1 2 3 4 5 6 7 8 Years After Planting Host Crop Pi(t+x)

Perennial Crops / Permanent Plantings Multiple Point Models Premises: Target nematode population is resident Population can be measured with acceptable precision Timeframe for population increase is long Management alternatives require decision prior to planting and ongoing management as needed Population must be measured periodically to determine trajectory are these premises valid?

Cropping System Design Agricultural versus Natural systems: Soil carbon 2. Soil food webs 3. Plant-parasitic nematodes

Nematodes at each trophic level Soil Food Web: Resource Flow among Functional Guilds Photosynthates Producers Fixers Sources Opportunists Immobilizers Consumers Mineralizers Top Predators Regulaters Nematodes at each trophic level

Food Web Complexity and the Regulation Function Management practices in industrialized agriculture result in: Soil food web simplification Reduction in higher trophic levels We tested evolving nematode predator:prey hypotheses with data from banana plantations in four Central American countries………. Costa Rica, 2008

Fungal-, bacterial-feeding Predators and prey – the Apparent Competition Hypothesis Generalist and Specialist Predators Amplifiable Prey Target Prey Fungal-, bacterial-feeding Nematodes Plant-feeding Nematodes

Amplifiable and target prey – the expanded model A=favorable conditions for predators Functional complementarity B=co-location of predators and prey Other Prey A E4 + Other Predators E1 + Predator Nematodes Root Associate Nematodes + E3 - + B - A B Amplifiable Prey Target Prey - Protozoa + E2 B + Nematophagous Fungi - E5 B + Rhizosphere Bacteria E6 - + Microbial Biomass + Organic Matter + + + Plant Roots Litter + External Sources 23 23

Sugarcane - Australia

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.