Some plant-parasitic nematodes exist within root tissue and must be extracted from the roots to identify and count them. However, efficiency comparisons of methods and solutions have not been published. We have tested if water is a better extraction solution than mercuric chloride-dihydrostreptomycin sulfate for recovery of lance and root-lesion nematodes in corn roots. Also, we have tested if the platform shaker method is more effective than the Baermann funnel for extracting these nematodes and if there is an interaction between extraction solution and extraction method in recovery of these nematodes from corn roots. In addition, we infected corn roots with root-lesion nematodes alone and compared the number of the nematode extracted from radical and seminal roots versus nodal roots using both methods and solutions described.

In the second portion of this thesis, we reported the screen of fifteen corn lines for resistant to Pratylenchus neglectus and Hoplolaimus stephanus. Screening would be the first step to provide sources of resistance for breeding programs. There is a lack of commercial corn lines resistant to root-lesion and lance nematode available. We also compared numbers of root-lesion and lance nematodes present in the radical and seminal roots and nodal roots of the fifteen different corn lines to check correlation between nematode numbers and root type.

The third portion of this thesis describes effect of the new seed treatment products available to protect corn roots from plant-parasitic nematodes. Experiments were conducted in 2011 and 2012 at five different locations in Iowa. The treatments were: Avicta® Complete Corn (Avicta® + Cruiser® + Maxim® Quattro); Cruiser® + Maxim® Quattro; Counter® + Cruiser® + Maxim® Quattro; Poncho® (500) / VOTiVO® + Acceleron® fungicides; and Poncho® 500 + Acceleron® fungicides. Plant-parasitic nematode population densities were accounted in the initial and at V5/V6 corn growth stage and corn yields were also accessed.