Effect of Postemergence Application Rate and Timing of Mesotrione on Corn (Zea mays) Response and Weed Control¹

Abstract

Field experiments were conducted in 1999 and 2000 to determine the influence of mesotrione postemergence application rate, application timing, and addition of atrazine on corn injury, weed control, and corn grain yield. Corn injury in the form of leaf bleaching ranged from 0 to 15% at 7 d after treatment (DAT). In general, most of the bleaching injury rapidly dissipated with slight (≤ 8%) to no corn injury observed at 28 DAT. Control of common cocklebur with mesotrione at 14 DAT ranged from 79 to 98% for all treatments over both years. Applying mesotrione at 140 g/ha, at the early postemergence (EPOST) timing, or in combination with atrazine provided the greatest control of common cocklebur at 14 DAT. Application rate of mesotrione was the only factor that was significant in both years for control of common cocklebur later in the season at 56 DAT. Control of ivyleaf morningglory with mesostrione at 14 DAT ranged from 60 to 90% for all treatments in both years. Control of ivyleaf morningglory at 14 DAT was enhanced by the addition of atrazine to mesotrione. Control of ivyleaf morningglory at 56 DAT was greater with mid-postemergence and late postemergence than with EPOST applications, and was generally enhanced by the addition of atrazine. Yellow nutsedge control with mesotrione was inconsistent, ranging from 40 to 87% at 14 DAT for all treatments over both years. The addition of atrazine to mesotrione increased yellow nutsedge control from 47 to 87% at 14 DAT in 2000. Increasing the rate of mesotrione from 70 to 140 g/ha, as well as the addition of atrazine, improved control of yellow nutsedge at 56 DAT. Corn grain yield was not affected by corn injury or weed control as there were no significant differences in grain yield between herbicide-treated plots and handweeded plots.

Response of selected glyphosate-resistant broadleaved weeds to premix of fluthiacet-methyl and mesotrione (Solstice™) applied at two growth stages

“…In addition, the rates required to achieve an acceptable response i.e., control and percent shoot biomass reduction varied between weed species (Tables 1 and 2). Johnson et al (2002) reported variable control of common cocklebur (Xanthium strumarium L.), ivyleaf morning glory (Ipomoea hederacea L.), and yellow nutsedge (Cyperus esculentus L.) following POST application of mesotrione; however, response was improved by increasing application rates.…”

“…The efficacy of herbicides is influenced by several factors including type of weed species present, growth stage, and herbicide application rates (King and Oliver 1992;Jordan et al 1993;Johnson 2002;Abendroth et al 2006). However, the use of herbicides at the labeled rate and appropriate crop and weed stages usually results in high weed mortality and crop safety.…”

Corn Injury from Foliar Zinc Application Does Not Affect Grain Yield

“…Curran et al (1991) reported that clomazone, chlorimuron, and imazaquin applied to V3 corn caused significant injury (up to 39% chlorosis) but did not affect corn yield. Similarly, Johnson et al (2002) observed foliar injury from the herbicide mesotrione applied to V3 to V5 corn but did not observe any yield differences between herbicide-treated and nontreated corn. Corn appears to be tolerant to injury during early-vegetative growth, indicating that the lack of grain yield response to foliar Zn injury is not unusual.…”

Maximum quantum yield of photosystem II to assist in the measurement of herbicide selectivity in popcorn

“…The mesotrione inhibit carotenoid biosynthesis, interfering with the activities of the enzyme HPPD (4-Hydroxyphenylpyruvate dioxygenase) in the chloroplasts, causing bleaching with subsequent necrosis and plant tissues death in about one or two weeks (Mitchell et al, 2001). Johnson, Young, & Matthews (2002) observed injuries to the maize plants seven days after the application of mesotrione, depending on the season and the dose applied.…”