|Timper, Patti - UNIVERSITY OF ARKANSAS|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 1996
Publication Date: N/A
Interpretive Summary: At least 15 species of root-lesion nematodes are reported to parasitize potatoes. These nematodes can cause losses of 15 to 73% of marketable yields. Pratylenchus penetrans is the most widespread species and the one that most commonly damages potatoes. This nematode also interacts with a fungal pathogen of potatoes and causes a disease known as early dying which hresults in even greater losses in potato production. Traditionally, root- lesion nematodes have been controlled with chemical nematicides. Issues concerning the safe use of these nematicides has forced a decline in their usage and a search for alternative methods of root-lesion nematode control. Our research on environmentally safe means of root-lesion nematode control has focused on host-plant resistance and microbial antagonists. We have realized some success in developing resistance in potato to the common species, P. penetrans, and have identified fungal pathogens of this nematode. During a diagnostic survey of a potato seed grower's field that suffered severe nematode damage, we discovered that the dominant species of root-lesion nematode was P. neglectus rather than P. penetrans. This species of root-lesion nematode is dominant on cereal grains in the midwest but had not been reported from this area. Further, we found that in this field the common species P. penetrans was being naturally controlled by a bacterial pathogen which was not affecting P. neglectus. This information underscores the importance of proper nematode species identification in developing biological controls and points to a potential natural control of the most widespread and damaging species of root-lesion nematode.
Technical Abstract: Soil samples were taken from a field in Wyoming County near Portagwille, New York in 1992 and 1993 where potatoes exhibited poor growth. The samples were collected every 2 m from three transects spaced 20 m apart. The number of Pratylenchus specimens recovered per 100 cm3 of soil was 134+/-8 (mean +/- SE) in 1992 and 195 +/- 12 in 1993. Two Pratylenchus species, P. neglectus (Rensch) Filiphev & Sch. Stek. and P. penetrans (Cobb) Filipjev Sch. Stek. were identified from the samples. Pratylenchus neglectus was recovered from all samples, whereas P. penetrans was recovered from 33% and 78% of the samples in 1992 and 1993, respectively. Where P. penetrans did occur, it consituted only 12-14% of the specimens. Spores of the nematode- pathogenic bacterium Pasteuria spp. were found attached to the cuticle of 60% of the P. penetrans specimens and to less than 1% of the P. neglectus specimens.