INFLUENCE OF AMMONIUM SULFATE ON GLYPHOSATE ABSORTPTION AND TRANSLOCATION IN COMMON LAMBSQUARTERS AND VELVETLEAF

Authors: KNEPP, ANDREW - UNIV OF ILLINOIS; WAX, LOYD; HART, STEPHEN - UNIV OF ILLINOIS

Submitted to: North Central Weed Science Society US Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 1/9/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Greenhouse studies were conducted to determine the sensitivity of common lambsquarters and velvetleaf when slyphosate was applied alone and with ammonium sulfate (AMS) at 20 g L-1. Subsequent laboratory studies were conducted to determine the physiological basis for the differential sensitivities of common lambsquarters and velvetleaf in response to the additions of AMS to glyphosate. GR50 values for common lambsquarters remained fairly constant at 378 g ha-1 for glyphosate applied alone and 413 g ha-1 for glyphosate plus AMS. The GR50 values for velvetleaf decreased dramatically from 510 to 93 g ha-1 for glyphosate applied alone and glyphosate plus AMS, respectively. Absorption of glyphosate increased over time in both common lambsquarters and velvetleaf up to 33 and 31% of applied 14C at 168 hours after treatment (HAT), respectively. The addition of AMS did not increase absorption of 14C-glyphosate in common lambsquarters. AMS increased absorption of 14C-glyphosate at 24, 48, and 168 HAT in velvetleaf. No increase in 14C translocation of the treated leaves were observed in common lambsquarters. An increase in acropetal and basipetal translocation of 14C-glyphosate was detected in velvetleaf with the addition of AMS at 24, 48, and 168 HAT. Total translocation of 14C at 168 HAT was 21% and 47% of absorbed 14C for treatments of glyphosate alone and with AMS, respectively. Increased control of velvetleaf by glyphosate plus AMS may be partially explained by greater levels of glyphosate absorption and subsequent translocation.