Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2004
Publication Date: September 1, 2004
Citation: Ingham, R.E., Mojtahedi, H., Brown, C.R. 2004. Challenges to management of root-knot nematode damage to potato caused by mixed populations. Journal of Nematology. 36(3):325. Technical Abstract: Root-knot nematodes are serious pathogens of potato (Solanum tuberosum) in the western United States, causing quality defects that result in reduced crop value or crop rejection. Meloidogyne chitwoodi is generally considered to be the most damaging species and has been reported from nearly all states west of the Rocky Mountains. Meloidogyne hapla also occurs in many western states and may be found alone or with M. chitwoodi. Southwestern states may also have populations of M. incognita, M. javanica or M. arenaria, but these areas account for less than 8% of potato production in western states. Two races are recognized for M. chitwoodi and can only be distinguished by differential host test, race 1 reproducing on 'Chantenay' carrot and not on 'Thor' alfalfa and race 2, which reproduces on alfalfa but not on carrot. A third isolate, originally identified as race 3, is the only known M. chitwoodi to establish on the clonal selection P1275187.10 of Solanum bulbocastanum, breaking resistance conditioned by R Mc1(bib) gene. Race 3 has since been considered as a virulent pathotype of race 2. Both races appear equally damaging to tuber quality, with the potential to cause economic damage at or below the detection limit of 1/250 cm3 soil. Populations of M. chitwoodi containing both races may also occur. The inability to easily identify and distinguish races introduces serious restrictions to developing cultural management strategies. For example, crop rotation to alfalfa would suppress race 1 but not race 2. In addition, potato breeding programs have found it more difficult to attain resistance to race 2 than to race 1.