In Bangladesh, weeds in transplanted rice are largely controlled by labor-intensive and costly manual weeding, resulting in inadequate and untimely weed control. Labor scarcity coupled with intensive rice production has triggered increased use of herbicides. These factors warrant a cost-effective and strategic integrated weed management (IWM) approach. On-farm trials with transplanted rice were conducted during monsoon (‘Aman’) season in 2016 and 2017 and winter (‘Boro’) season in 2016 to 2017 in agroecological zones 11 and 12 with ten treatments—seven herbicide-based IWM options, one mechanical weed control-based option, and two checks (farmers’ current weed control practice and weed-free)—to assess effects on weed control, grain yield, labor use, and profitability. Compared to farmers’ practice, herbicide-based IWM options with mefenacet + bensulfuron-methyl as preemergence followed by (fb) either bispyribac-sodium or penoxsulam as postemergence fb one hand-weeding were the most profitable alternatives, with reductions in labor requirement by 11 to 25 person-days ha–1 and in total weed control cost by US$44 to 94 ha–1, resulting in net returns increases by US$54 to 77 ha–1 without compromising on grain yield. In contrast, IWM options with bispyrbac-sodium or penoxsulam as postemergence application fb one hand-weeding reduced yields by 12% to 13% and profits by US$71 to 190 ha–1. The nonchemical option with mechanical weeding fb one hand-weeding performed similarly to farmers’ practice on yield and profitability. We suggest additional research to develop feasible herbicide-free approaches to weed management in transplanted rice that can offer competitive advantages to current practices.

Cooperative research was initiated by a multidisciplinary team of weed scientists and agricultural economists in 1975 that laid the foundation for integrated weed management research in Colorado. Colorado's integrated weed management research has four phases: weed seed bank decline, systems approach to weed management, bioeconomic modeling, and multiple weed management tactics. Each phase considered weed seed bank, weed control efficacy, weed control costs, crop yield, and gross margin. All four phases emphasize the need for a weed management system that minimizes seed production in situations where a high soil weed seed bank exists. However, once the weed seed bank is reduced, a weed management program with less than 100% weed control can be employed without increasing the seed bank. Intensive weed management systems are seldom justified when economics, weed control, and weed seed bank are considered. Integrated weed management approaches require integrating crop and weed biology with management tactics. Integrated weed management requires advanced managerial skills and often more time than traditional approaches.

Herbicide-resistant weeds are becoming a major problem in the Midwest, and strategies must be adopted to delay further selection. Strategies of rotating and tank-mixing herbicides with different modes of actions should be effective, but adoption may be limited and certain limitations may exist. Therefore, integrating nonchemical practices that indirectly lower selection pressure or restrict the growth of resistant populations is desirable. Appropriate integration of mechanical weeding, crop rotation, increased crop competition, and decision aids may further delay the development of resistance. Understanding the effect of these practices on weed population dynamics is required to more accurately predict their contributions toward resistance management. This knowledge will aid in justifying the adoption of improved management systems.

An increasing number of farm machines nowadays implement precision agriculture technologies. Most of these operate through proximal sensing using optical sensors (i.e. NIR or Vis-NIR). Imaging techniques in this context have received minor consideration due to the complex analysis of the data but on the other side offer great flexibility. This study reports a preliminary pilot imaging multi-sensor retrofit system to be applied independently on a wide range of agricultural machines and able to test different monitoring or control image-based applications for precision agriculture. The process, based on RGB image, was tested for in-field discrimination of weeds in lettuce and broccoli crops. It works by discriminating and extracting single plants from the soil and weeds. However, to be truly implementable, the experimental code should be optimized in order to shorten the time needed for acquisition and processing.

The effect of weed interference on corn yield and the critical period for weed control (CPWC) were determined in Germany and Benin. Treatments with weed control starting at different crop growth stages and continuously kept weed-free until harvest represented the “weed-infested interval.” Treatments that were kept weed-free from sowing until different crop growth stages represented the “weed-free interval.” Michaelis–Menten, Gompertz, logistic and log–logistic models were employed to model the weed interference on yield. Cross-validation revealed that the log–logistic model fitted the weed-infested interval data equally well as the logistic and slightly better than the Gompertz model fitted the weed-free interval. For Benin, economic calculations considered yield revenue and cost increase due to mechanical weeding operations. Weeding once at the ten-leaf stage of corn resulted already profitable in three out of four cases. One additional weeding operation may optimize and assure profit. Economic calculations for Germany determined a CPWC starting earlier than the four-leaf stage, challenging the decade-long propagated CPWC for corn. Differences between Germany and Benin are probably due to the higher yields and high costs in Germany. This study provides a straightforward method to implement economic data in the determination of the CPWC for chemical and nonchemical weed control strategies.

A 3-yr study was conducted to assess cranberry bean susceptibility to mechanical weeding using a rotary hoe at preemergence, hook, cotyledon, unifoliate, and first to fourth trifoliate stages of bean development and at different combinations of stages. The experiment was conducted in a weed-free environment. Cultivation with the rotary hoe reduced bean yield only for the treatment that received four cultivations at four different bean growth stages. Three cultivations improved yield compared with no cultivation. Single cultivation done at any of the eight crop growth stages did not affect yield. Crop density at harvest was decreased 6% in the treatments receiving two cultivations and 9% in the treatments receiving four cultivations compared to no cultivation. The effects of the cultivations on grain moisture were not consistent and differed from year to year. Seed weight did not differ among treatments in either year. Because this study was conducted under weed-free conditions, the beneficial effects of cultivating with the rotary hoe are probably mostly related to breaking the soil crust, improving soil aeration, preserving soil moisture, or promoting mineralization of the nutrients required by the crop.