Plant parasitic nematodes have long been known to cause extensive crop losses through reduced yields, shortened productive life, or lowered value of produce. The rood knot nematode, Heterodera marioni, is cosmopolitan. It destroys crops and causes economic losses equal to those of any other plant parasitic speies. in 1948 this nematode caused an estimated loss to the carrot raising industry in Iron County, Utah of approximately $15,000. No estimates for the years prior to 1948 are available; however, reports of the county agent (14) for Iron County show that carrot production in the Cedar Valley is decreasing, and is possibly due to this nematode. The importance of the root knot nematode to the carrot industry in the Cedar Valley was Recognized by farmers at harvest time in 1948. Experimental applications of soil fumigants were tried on many farms with varying success in the spring of 1949. (See figure 1 page 2). One of these experimental plots showed spectacular results. When carrots were harvested in the fall those grown in fumigated soil were found to be of the highest quality and were growing in excellent stands; wheras, the carrots grown in unfumigated soil produced poorer stands of poor quality carrots. Before any conclusions as to the practical value of soil fumigants in carrot raising can be reached, additional tests must be conducted in the area. The fact remains that the root knot nematode is present in the area and causes damage to carrots. If carrots, or any other susceptible crops, are to be grown on economical method of controlling this nematode must be found.