A glasshouse study was established at Louisiana State University campus in Baton Rouge, LA, to evaluate the control of fall panicum and Nealley’s sprangletop treated with florpyrauxifen-benzyl. Florpyrauxifen was applied at 30 g ai ha–1 to each grass species at the three- to four-leaf and one- to two-tiller stages of growth. At 21 d after treatment (DAT), fall panicum control was 91% when treated with florpyrauxifen at the three- to four-leaf stage, and Nealley’s sprangletop control was 78% to 82%, regardless of application timing 21 DAT. Leaf number, tiller number, plant height, and plant fresh weight were reduced when fall panicum and Nealley’s sprangletop were treated with florpyrauxifen. This information can be useful for developing weed management strategies with this herbicide for rice production, and it provides an additional mode of action to help manage and/or delay the development of herbicide-resistant weeds.

A 6-yr project comparing four cash grain–farming systems relevant to the mid-Atlantic region of the United States was conducted from 1993 to 1999. A wide range of parameters was sampled including soil health, nutrient and agrichemical movement, economic viability, and insect and weed communities. The systems and their approaches to weed management were: continuous no-till corn without (System A1) or with (System A2) rye cover crop and preplanned herbicides based on expected weed infestations; System B was a 2-yr corn–soybean rotation with conventionally tilled corn and no-tillage soybean, with preplanned herbicides based on expected weed infestations; System C was a 2-yr rotation with no-till corn, conventionally tilled wheat, and no-till double-cropped soybean, using postemergence (POST) herbicides on the basis of field scouting; and System D was a 3-yr rotation of corn-soybean-winter wheat with rye and hairy vetch cover crops, using cultivation and reduced rates of POST herbicides based on field scouting. Spring weed assessment in 1999 was similar for species evenness (Shannon's E) and diversity (Shannon's H′) indices. Weed density was lowest in System C because wheat in this system received a spring herbicide application. In the final fall assessment, Shannon's H′ was greater in System D than System C. Common lambsquarters, eastern black nightshade, and jimsonweed were more abundant in System D than Systems A1, A2, and C. Fall 1999 assessment also indicated Canada thistle was more prevalent in Systems A1 and A2 than the other three systems. During the 6-yr period, densities of jimsonweed, eastern black nightshade, morningglory species, crabgrass, and fall panicum dramatically increased in a particular system for 1 to 2 yr, then declined to levels similar to other systems. Overall, weed communities were quite stable and effective weed management did not result in dramatic changes in the weed community, regardless of the approach to cropping systems or weed management.

Fall panicum is the most troublesome annual grass weed in sugarcane in Florida. The critical timing of fall panicum removal in sugarcane or the maximum amount of early season interference that sugarcane can tolerate before it suffers irrecoverable yield loss is not known. Field studies were conducted from 2012 to 2015 in Belle Glade, FL to determine the critical timing of fall panicum removal and season-long interference in sugarcane. The effect of season-long fall panicum interference and critical timing of removal based on 5 and 10% acceptable yield loss (AYL) levels were determined by fitting a log-logistic equation to percentage millable stalk, cane, and sugar yield loss data. Millable stalks, cane, and sucrose yield decreased as the duration of fall panicum interference increased. Season-long interference of fall panicum resulted in 34 to 60%, 34 to 62%, and 44 to 60% millable stalk, cane, and sucrose yield loss, respectively. The critical timing of fall panicum removal based on 5 and 10% AYL for millable stalks was 5 to 9 wk after sugarcane emergence (WAE). At 5 and 10% AYL, the critical timing of fall panicum removal ranged from 5 to 9 WAE and 6 to 8 WAE for cane and sucrose yield loss, respectively. These results show that fall panicum is competitive with sugarcane early in the season, demonstrating the need for timely early-season control to reduce negative effect on yield.