Citrus root-knot nematode - Meloidogyne citri

EEffective: August 18, 2010 - December 31, 2011
Resources: Pest Tracker Data Entry Guide for Nematodes
Screening Aids:
Taxonomic Position: Tylenchida : Heteroderidae
Pest Type: Nematodes
Pest Code (NAPIS): NEOBQHA
No manual – See Host Matrix
These Approved Methods are appropriate for:
Pest is vectored by:
This pest is is not known to be a vector and it is not vectored by any organism.
Survey
Approved Method(s):
Method Instructions NAPIS Survey Method
Soil Sample Send sample to nematology diagnostic lab where nematodes will be extracted and identified. 3012 - General Soil Sample
Tissue Sample Collect abnormally swollen roots and send to a nematology diagnostic lab where damage and galled roots will be assessed. 3011 - General Tissue Sample
Signs:
Nematode egg masses are often visible on the surface of galls.
Symptoms:
Root-knot nematodes (RKNs) symptoms are similar to those caused by nutrient or water deficiency, including stunting, wilting, and chlorosis of leaves. Small root galls and lateral proliferation of roots is also observed with most species. For citrus RKNs, yellowing of leaves, premature flower drop, early ripening and fruit drop, and reduced fruit quality and yield are observed. Citrus roots infected by root-knot nematodes show swollen rot tips and axes.
Key Diagnostics


ID/Diagnostic: Morphological

1. Assessment of root galls will indicate a possible root knot nematode infection.

2. Morphological: The length of at least 20 second-stage juveniles, the head and stylet morphology of males, and the nature perineal patterns of females from samples.
Mistaken Identities:
Other Meloidogyne species (M. arenaria, M. hapla, M. incognita, M. javanica)
Notes:
The occurrence of RKNs on weeds is common in citrus groves. Soil samples from these groves are often positive for root-knot nematode because they originate from weed hosts. Careful examination and separation of roots in the samples provides certainty of the origin of nematode infestation.
References
  1. Davis, E.E. and Venette, R.C. 2004. Mini Risk Assessment - Asian Citrus Root-knot Nematodes: Meloidogyne citri; M. donghaiensis; M. fujianensis; M. indica; M. jianyangensis; M. kongi; and M. mingnanica. Cooperative Agricultural Pest Survey, Animal and Plant Health Inspection Service, US Department of Agriculture.
  2. Hunt, D. J., and Handoo, Z. A. 2009. Taxonomy, Identification and Principal species. In: Root-knot nematodes. Perry, R. N., Moens, M., and Starr, J. R. (ed.) CABI Publishing, UK. pp. 55-97.
  3. Perry, R. N., Moens, M., and Starr, J. R. (ed.). 2009. Root-knot nematodes. CABI Publishing, UK, 488 pp.