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Title: Sampling techniques and detection methods for developing risk assessments for root-knot nematode (Meloidogyne incognita) on lima bean (Phaseolus lunatus) in the Mid-Atlantic region

Author
item SMITH, KRISTINA - University Of Delaware
item JOHNSON, GORDON - University Of Delaware
item EVANS, TOM - University Of Delaware
item Meyer, Susan
item DESAEGER, JOHAN - Dupont Crop Protection
item BAKER, HEATHER - University Of Delaware

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/11/2014
Publication Date: 11/1/2014
Citation: Smith, K.M., Johnson, G.C., Evans, T.A., Meyer, S.L.F., Desaeger, J.A., Baker, H.N. 2014. Sampling techniques and detection methods for developing risk assessments for root-knot nematode (Meloidogyne incognita) on lima bean (Phaseolus lunatus) in the Mid-Atlantic region. Phytopathology. 104(S3):163.

Interpretive Summary:

Technical Abstract: Lima bean, Phaseolus lunatus, is a cornerstone crop in the Mid-Atlantic region and Meloidogyne incognita, the southern root knot nematode (RKN), causes significant yield loss. The RKN has become more pervasive as toxic nematicides have been removed from the market, and risk evaluation research is needed to offset crop losses. In 2013 eight lima bean production fields, 7 in southern Delaware and 1 from Maryland's Eastern Shore, were divided into geo-referenced 1 hectare grids and sampled three times a year. Samples were taken: before crop planting, after lima beans had pinned and podded, and directly after harvest. Edaphic features (pH, EC, temperature, moisture, elevation and texture) were measured during the first sampling period, and additional soil was collected to conduct a bioassay for use in measuring dormant RKN. Subsequent samples of soil and plant material were taken for laboratory analysis of root galls and second-stage juveniles (J2) in soil. Preliminary findings indicate that a spring, pre-planting bioassay is better correlated with levels of post harvest nematodes than are spring samples of J2 from soil. Correlations between edaphic features and nematode levels were inconclusive. Pigweed, Amaranthus hybridus, a suitable host for RKN, was found to correlate with higher levels of galling on lima bean and higher levels of J2 in soil. In addition to sampling during the growing season, weather and moisture data are currently being collected to measure overwinter survival rates, and RKN levels will be measured in March 2014. Data collected on RKN population dynamics will be used to create a risk assessment model.