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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #173745
Title: PHYTOTOXICITY OF DELAYED APPLICATIONS OF FLUMIOXAZIN ON PEANUT (ARACHIS HYPOGAEA)

Author
item Johnson, Wiley - Carroll
item PROSTKO, ERIC - UNIV. OF GEORGIA
item MULLINIX, JR., BENJAMIN - UNIV. OF GEORGIA

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2005
Publication Date: 1/17/2006
Citation: Johnson,III, W.C., Prostko, E.P., Mullinix, Jr., B.G. 2006. Phytotoxicity of delayed applications of flumioxazin of peanut (Arachis hypogaea). Weed Technology. 20:157-163.

Interpretive Summary: Flumioxazin (Valor®) has been recently registered for preemergence weed control in peanut. Flumioxazin effectively controls many troublesome weeds of peanut, but can be injurious when applied to emerged peanut. Weed free trials were conducted in 2001, 2002, and 2003 on a loamy sand soil in Georgia to investigate the phytotoxicity of delayed flumioxazin applications on peanut and in separate trials, the effects on peanut maturity. The first set of trials evaluated times of flumioxazin application (0, 2, 4, 6, 8, and 10 days after planting) and flumioxazin rate (nontreated, 2, and 3 oz/A). 'C99R' peanut were shallow seeded (1.25 in. deep) and irrigated immediately after seeding. Flumioxazin applied to peanut 6, 8, and 10 DAP significantly injured peanut, with more phytotoxicity from flumioxazin at 3 oz./A than 2 oz./A. However, stand was not reduced by any of the times of application or rates. Peanut recovered by mid-season, except in cases of severe phytotoxicity. Peanut yields were not affected by either flumioxazin time of application or rate. Other trials evaluated flumioxazin applied at 3 oz./A to 'Georgia Green' peanut at varying intervals after planting to determine the phytotoxic effects on peanut maturity using the Hull Scrape Method. Peanut maturity was delayed by flumioxazin when applied 1 day after planting and later. These results show that the optimum time of application is immediately after planting to 2 days after planting, but within that range the earlier applications are suggested. The highest recommended flumioxazin rate, 3 oz./A, is not overly phytotoxic when applied within the recommended range of timings and has no effect on yield. Peanut growers need to consider the risk of severe flumioxazin injury and logistical difficulties posed by the narrow time interval for safe application with the benefits of excellent Florida beggarweed control it provides.

Technical Abstract: Weed free trials were conducted in 2001, 2002, and 2003 on a loamy sand soil in Georgia to investigate the phytotoxicity of flumioxazin on peanut and in separate trials, the effects on peanut maturity. The first set of trials evaluated times of flumioxazin application (0, 2, 4, 6, 8, and 10 days after planting) and flumioxazin rate (nontreated, 71, and 105 g ai/ha). 'C99R' peanut were shallow seeded (3.2 cm deep) and irrigated immediately after seeding. Flumioxazin applied to peanut 6, 8, and 10 DAP significantly injured peanut, with more phytotoxicity from flumioxazin at 105 g/ha than 71 g/ha. However, stand was not reduced by any of the times of application or rates. Peanut recovered by mid-season, except in cases of severe phytotoxicity. Peanut yields were not affected by either flumioxazin time of application or rate. Other trials evaluated flumioxazin applied at 105 g/ha to 'Georgia Green' peanut at varying intervals after planting to determine the phytotoxic effects on peanut maturity using the Hull Scrape Method. Peanut maturity was delayed by flumioxazin when applied 1 day after planting and later. These results show that the optimum time of application is immediately after planting to 2 days after planting, but within that range the earlier applications are suggested. The highest recommended flumioxazin rate, 105 g/ha, is not overly phytotoxic when applied within the recommended range of timings and has no effect on yield. However, there is potential for yield loss since peanut maturity is delayed in cases of severe phytotoxicity.