Observations on the prevalence and abundance of plant-parasitic nematodes were made from soil and root samples collected from 2,640 wheat fields in Kansas and Colorado during 2007-2010. Stunt nematodes (predominately Merlinius brevidens and Quinisulcius acutus), root-lesion nematodes (predominately Pratylenchus neglectus), and pin nematodes (Paratylenchus projectus) were the most commonly encountered taxa. Maximum soil population densities of 6,520 and 1,880 nematodes/100 cm3 soil were observed for pin and stunt nematodes, respectively, while a maximum root population density of 90,309 nematodes/g dry root was observed for root-lesion nematodes. Lower nematode densities were associated with wheat following corn, grain sorghum, or soybean for pin and stunt nematodes, and with wheat following fallow for root-lesion nematodes. Based on the results of this survey, 6% and 8% of wheat acreage in the central Great Plains are estimated to be at risk for significant (>5%) yield loss due to stunt nematodes and root-lesion nematodes, respectively. The number of fields with high population densities of both stunt and root-lesion nematodes was negligible (1%); therefore, the total wheat acreage with nematode populations above provisional economic thresholds is estimated to be ∼13%. Damage relationships with greater accuracy, precision, and relevance are necessary to establish reliable yield loss estimates for this region. 3 June 2014. 11 August 2014.
Nematode Management in Cole Crops
