Nematode Thresholdsand

Damage Levels

Annual and Perennial Crops

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 StationUSDA ShafterTulelake

Thresholds by transectImperial and Coachella Valleys

Ventura CountyTulare 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

0

0.2

0.4

0.6

0.8

1

1.2

0 2 4 6 8

Ln (Pi+1)R

elat

ive

Yie

ld

Case Study on Cotton

Cultivar Soil Location (T)olerance Z m

SJ2 loamy sand south SJV 65 0.998 0.55

Deltapine loamy sand imperial 50 0.9972 0.65

SJ2, SJ5, SJ-C1 l. sand/s. loam south SJV 55 0.999 0.48

average (all) --------------------- ------------- 57 0.998 0.56

average (SJV) --------------------- ------------- 60 0.9985 0.52

SJ2(-FOV) sandy loam south SJV 55 0.9966 0.54

SJ2(+FOV) sandy loam south SJV 55 0.9847 0.38

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 0 5 15 27 41

Deltapine loamy sand imperial 19 0 7 16 26 34

SJ2, SJ5, SJ-C1 l. sand/s. loam south SJV 21 0 4 10 19 37

average (all) --------------------- ------------- 22 0 6 15 27 40

average (SJV) --------------------- ------------- 23 0 5 12 24 41

SJ2(-FOV) sandy loam south SJV 21 0 10 23 37 45

SJ2(+FOV) sandy loam south SJV 21 0 42 59 62 62

Case Study on Cotton

Damage Function Parameters for Selected Crops

Crop (T)olerance Z m

Bell Pepper 65 0.9978 0.87

Cantaloupe 10 0.9972 0.40

Carrot 0 0.99 0.6

Chile Pepper 39 0.9934 0.70

Cotton 57.5 0.9976 0.6

Cowpea 22 0.9816 0.96

Potato 18 0.99 0.49

Snapbean 14 0.9978 0.57

Squash 0 0.9898 0

Sugarbeet 0 0.9955 0.89

Sweetpotato 0 0.99375 0.47

Tomato 41.8 0.99934 0.47

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 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

Sweetpotato 0 1 2 4 8 15 30 43 51

Tomato 16 0 0 0 0 0 3 7 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 cc 1 2 5 10 20 50 100 200 500

% Blemish 3 4 5 7 8 12 15 18 25

Thresholds and Expected Yield Loss

Cultivar Soil Location (T)olerance Z m

US-H9 clay Imperial 100 0.99886 0

US-H9 loam SJV/Idaho 300 0.99976 0

Heterodera schachtii, eggs/100g soil

Sugarbeets

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

Expected % yield loss at different preplant nematode densities

Mesocriconema xenoplax

Bacterial canker of Prunus

Mesocriconema

Mesocriconema

Mesocriconema xenoplax

Mesocriconema

Mesocriconema

Some ReferencesBenedict, 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.