Effect of Pyridate Formulation and Adjuvants on Broadleaf Weed Control in Peanut (Arachis hypogaea)1

Abstract

Field studies were conducted near Archer, FL, and Vienna, GA, in 1995 and 1996 to investigate the effects of pyridate formulation and adjuvants on broadleaf weed control in peanut (Arachis hypogaea). Pyridate formulations SAN 319H 450EC 361LZ, SAN 319H 450EC 216LZ, and SAN 319H 600EC 418LZ were evaluated at two rates, 1.07 and 2.14 kg/ha. Pyridate at 1.07 kg/ha plus 2,4-DB at 0.23 kg/ha were evaluated alone and with five adjuvants. The adjuvants included a crop oil concentrate, a nonionic surfactant, a nonionic surfactant with organosilicone blend, urea ammonium nitrate plus a nonionic surfactant, and chlorothalonil (a fungicide) plus a nonionic surfactant. No pyridate treatment injured peanut. Pyridate formulation did not affect broadleaf weed control. Increasing pyridate rate increased weed control and yield. Mixing 2,4-DB with pyridate generally enhanced sicklepod (Senna obtusifolia) and common cocklebur (Xanthium strumarium) control. Florida beggarweed (Desmodium tortuosum), smallflower morningglory (Jacquemontia tamnifolia), hairy indigo (Indigofera hirsuta), sicklepod, and common cocklebur control with pyridate was not enhanced by adjuvants. Adding chlorothalonil to pyridate plus 2,4-DB did not affect weed control or peanut injury.Nomenclature: 2,4-DB; chlorothalonil; tetrachloroisophthalonitrile; pyridate; common cocklebur, Xanthium strumarium #3 XANST; Florida beggarweed, Desmodium tortuosum # DEDTO; hairy indigo, Indigofera hirsuta # INDHI; peanut, Arachis hypogaea ‘Sunrunner’ and ‘GK-7’; sicklepod, Senna obtusifolia # CASOB; smallflower morningglory, Jacquemontia tamnifolia # IAQTA.Additional index words: SAN 319H 450EC 361LZ, SAN 319H 450EC 216LZ, SAN 319H 600EC 418LZ, crop oil concentrate, nonionic surfactant, organosilicone-nonionic surfactant blend, urea ammonium nitrate.Abbreviations: COC, crop oil concentrate; NIS, nonionic surfactant; NIS/OS, nonionic surfactant with organosilicone; POST, postemergence; WAT, weeks after treatment.