Broadleaf Weed Control in Soybean (Glycine max) with CGA-277476 and Four Postemergence Herbicides¹

Abstract

Field research was conducted at three locations in Mississippi to evaluate CGA-277476 tank mixtures with four broadleaf herbicides for possible improvement of broadleaf weed control. Tank mixtures in this research were typically additive, although some instances of antagonism were noted. Control of morningglory (Ipomoea) species and hemp sesbania (Sesbania exaltata) was not consistently improved by the addition of acifluorfen, chlorimuron, fomesafen, or imazaquin to 59 or 79 g ai/ha CGA-277476. However, when a large population of weeds was present, the addition of acifluorfen, chlorimuron, or fomesafen to 59 or 79 g/ha CGA-277476 improved control over CGA-277476 alone. Prickly sida (Sida spinosa) was not controlled more than 68% with any treatment in this study; however, horse purslane (Trianthema portulacastrum) was controlled at least 90% with either 79 g/ha CGA-277476 alone or tank-mixed with acifluorfen, fomesafen, chlorimuron, or imazaquin. The addition of CGA-277476 to acifluorfen or fomesafen did not improve control over acifluorfen or fomesafen alone on any of the weeds evaluated; however, the addition of CGA-277476 to imazaquin improved hemp sesbania control over imazaquin alone. Tank mixtures did not result in yields greater than CGA-277476 alone in areas with moderate weed pressure, whereas in areas with severe weed pressure, tank mixtures improved soybean (Glycine max) yield over CGA-277476 alone.

Weed Control and Potato (Solanum Tuberosum) Crop Response With Low Rates of Sulfentrazone Applied Postemergence With Metribuzin

“…Other researchers have speculated that stressed plants do not absorb herbicides as fast as more healthy plants (Palmer et al 2000); therefore, stress caused by the metribuzin in the tank mixtures may have reduced sulfentrazone uptake by potato plants in our study. postulated that sulfentrazone movement occurs by transpirationdriven apoplastic mechanisms.…”

Early‐Season Lactofen Application has Limited Effect on Soybean Branch and Mainstem Yield Components

“…Furthermore, if soybean of the appropriate maturity are sown at an adequate seeding rate and row spacing to allow for a critical number of nodes to develop, the addition of more nodes via any mechanism is very unlikely to increase soybean pod and seed numbers. On the other hand, diphenyl ether herbicides have become increasingly important for control of broadleaf weed species, such as palmer amaranth ( Amaranthus palmeri S. Watson), that have become resistant to other herbicidal modes of action (Mayo et al, 1995; Palmer et al, 2000; Norsworthy et al, 2008). Growers concerned about the damage caused by the diphenyl ether herbicides can be confident that application of products containing these herbicide compounds will not affect soybean pod and seed production nor, ultimately, yield.…”

Cloransulam Antagonizes Annual Grass Control with Aryloxyphenoxypropionate Graminicides But Not Cyclohexanediones

“…Combinations of APP and CHD herbicides with herbicides used to control broadleaf weeds typically result in antagonistic reactions (Barnwell and Cobb 1994;Brommer et al 2000;Croon and Merkle 1988;Culpepper et al 1999;Devine and Rashid 1993;Ferreira and Coble 1994;Minton et al 1989;Vidrine 1989;Whitwell et al 1985). Antagonism has been successfully alleviated by increasing the application rates of the graminicide in the mixture as well as by applying the herbicides sequentially with herbicide applications separated by a few days (Barnwell and Cobb 1994;Croon and Merkle 1988;Culpepper et al 1999;Ferreira and Coble 1994;Minton et al 1989;Palmer et al 2000). Many broadleaf-graminicide combinations have been classified as antagonistic by researchers.…”

“…Antagonism of the graminicides by the ALS-inhibiting herbicides has not been fully explained. Graminicide antagonism by ALS inhibitors could be linked to the level of activity the ALS herbicides have on annual grasses, but no physiological basis for this theory has been discovered (Burke and Wilcut 2003;Devine and Rashid 1993;Mathiassen and Kudsk 1998;Palmer et al 2000). Ditmarsen et al (1997) reported antagonism of the APP herbicides, fluazifop-P, quizalofop, and fluazifop-P plus fenoxaprop, when mixed with cloransulam but no antagonism of the CHDs, sethoxydim, and clethodim.…”