Published online by Cambridge University Press: 12 June 2017
3-Amino-1,2,4-triazole (amitrole) sprayed on annual grassland infested with medusahead (Elymus caput-medusae L.) at 1/2 to 4 lb/A when medusahead was in the boot or soft dough stage reduced viable caryopses from 60 to 100 percent, and seed production the following year from 75 to almost 100 percent. 1,2-Dihydropyridazine-3-6-dione (maleic hydrazide) and 2,2-dichloropropionic acid (dalapon) reduced viability of medusahead seeds, but were less effective than amitrole. Viable caryopses of soft chess (Bromus mollis L.) were reduced and the year following treatment soft chess was decreased in the stands by early application (boot stage of medusahead) but not by late application of herbicides, when the soft chess heads were dry.