Paraquat Kills Geyer Larkspur

Abstract

Geyer larkspur, a poisonous, perennial forb, is highly susceptible to paraquat applied when flowering stems are slightly above ground. At 1/2 lb./acre, paraquat killed 90 to 95% of geyer larkspur, but was less effective when the treatment was preceded with 2,4-D at 2 lb./acre. Textile onion and most annual species were susceptible to paraquat, while all other perennial species were resistant. There was some reduction in herbage yields in the year of treatment. Although paraquat is not registered for controlling geyer larkspur, it could be considered for that purpose.