Effects of 2,4,5-T and Picloram on Broom Snakeweed in Arizona

Abstract

Foliar-spray and soil herbicidal treatments were made on broom snakeweed (Gutierrezia sarothrae) in a shortgrass vegetation type in central Arizona. Broom snakeweed was effectively controlled with foliar treatments of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) applied at 4 lb/acre in April and May. Foliar and soil (granular) treatments of 4-amino-3,5,6-trichloropicolinic acid (picloram) applied at 0.5 lb/acre were effective from February through March and September through December, respectively. Herbicide effectiveness was influenced by soil moisture and stage of plant growth, but apparently was not directly influenced by relative humidity, air temperature, soil temperature, time-of-day of application, or additives of glucose and boron. The effectiveness of 2,4,5-T was greatly increased by the addition of 10% diesel oil in the spray mixture when applied at the rate of 50 gpa. The effectiveness of 2,4-dichlorophenoxyacetic acid (2,4-D) on snakeweed was similar to that of 2,4,5-T./El estudio se llevó a cabo en un tipo de vegetación de zacates cortos en el centro del estado de Arizona tendiente a combatir "Broom snakeweed" (Gutierrezia sarathrae), una hierba tóxica abundante en los pastizales de Estados Unidos y México. La planta fue controlada efectivamente con la aplicación foliar de 4.0 lb/acre de 2,4,5-T durante los meses de abril y mayo, siendo su acción fuertemente aumentada agregando 10% de Diesel, similar resultado se obtuvo aplicando 0.5 lb/acre de Picloram en forma foliar en los meses de febrero y marzo. Igual dosis, pero de picloram granulado, fue efectivo de septiembre a diciembre. La efectividad del hervicida se vio influida por la humedad del suelo y época de crecimiento de las plantas.