Five fumigants (anhydrous ammonia, chloropicrin, dichloropropene, metham sodium, and methyl bromide) were evaluated for toxicity to sclerotia of Phymatotrichum omnivorum. The dose (mg/liter) required to kill 95% of the sclerotia during an exposure period of 4 hr was: anhydrous ammonia 18, chloropicrin 47, dichloropropene 136, metham sodium 169, and methyl bromide 176. At 250 mg/liter anhydrous ammonia killed all sclerotia in 30 min. Activity of the fumigants was a function of concentration x time. Dosage response equations were calculated for the fumigants.