Response of Peanut, Corn, Tobacco, and Soybean to Criconemella ornate

The relative susceptibility of four field crops to Criconemella ornata differed greatly in microplot tests. As few as 178 freshly-introduced C. ornata/500 cm³ of soil stunted peanut. In contrast, this nematode had no effect on the growth of corn or soybean. Large populations remaining after culture of peanut or corn enhanced the growth of tobacco. A problem of comparing the effects of a freshly introduced population of this nematode with large residual populations was encountered. Freshly extracted, greenhouse-grown inoculum caused the typical "yellows disease" on peanut, whereas much greater residual population densities following a poor host (tobacco) had little effect on the growth of peanut. It is suggested that many of the nematodes in the field following a poor host are dead. Peanut supported greater reproduction (up to 970-fold) than did other crops tested. Corn was intermediate, with a population increase as great as 264-fold; soybean and tobacco failed to maintain initial population densities.