Management of broadleaf weeds in chile pepper may be improved by including a rotation with sorghum treated with selective, non-residual herbicides. However, herbicide programs within sorghum specifically for managing weeds in subsequent chile pepper have not been evaluated. This study evaluated the effects of two herbicide programs applied in sorghum on broadleaf weed density and hand hoeing time in chile pepper the following year, and compared the programs for their net economic benefits across sorghum and chile pepper growing seasons. Treatments were: 1) sorghum non-treated control, 2) one herbicide application, which was a premix combination of 2,4-D (0.35 kg ai ha-1), bromoxynil (0.35 kg ai ha-1), and fluroxypyr (0.14 kg ai ha-1) applied at the 4-leaf stage of sorghum, 3) two herbicide applications, which included the aforementioned premix combination followed by bromoxynil (0.28 kg ai ha-1) applied at the 6-leaf stage of sorghum, and 4) weed-free sorghum using hand hoeing. Results indicated broadleaf weeds covered less than 10% of the ground in sorghum treated with herbicides. The two-application program resulted in 24% fewer broadleaf weeds in chile pepper than in sorghum hand-hoed, and 63% fewer than the one-application program. Hand hoeing time in chile pepper was similar among the two-application program, one-application program, and weed-free sorghum. A partial budget analysis indicated that the one-application program provided greater net economic benefit than the two-application program (US$6,550 ha⁻¹ vs. US$5,894 ha⁻¹), due to lower input costs and greater overall gross revenue. These findings indicate the two-application program maximizes reductions of broadleaf weeds in chile pepper caused by rotational sorghum; however, the one-application program may be a cost-effective approach to reduce broadleaf weeds in chile pepper.

The effect of N levels, weed control treatments, and their interaction on maize yield and weed growth in sandy soils is not completely understood. Therefore, field experiments were conducted during 2005 and 2006 to determine if management can improve maize competitiveness with weeds, and thus achieve the yield potential of maize in sandy soils. The experiment included three N levels (300, 338, and 375 kg/ha) and five weed control treatments, e.g., hand hoeing twice, hand hoeing three times, fluroxypr + hoeing once, hoeing once + bispyribac-Na, and a nonweeded check. N rates affected dry weight of weeds growing with maize except with large crabgrass. Biomass of common purslane, considered a nitrophilous species, was increased by all N levels. Weeds were controlled by all treatments compared with the nontreated check; however, herbicide treatments were not superior to hand-hoeing treatments. Using more N favored growth and yield of maize more than weeds. Adding N fertilizer also improved most yield parameters. Highest grain yield of maize resulted at 375 kg/ha N. All weed control treatments improved grain yield two- to threefold compared with the nonweeded check. The interaction between N rates and weed control treatments had significant effects on dry biomass of common purslane and barnyardgrass, as well as grain index and biological yield parameters of maize. Grain yields were improved with fluroxypyr applied 2 wk after sowing (WAS) maize followed by one hand hoeing 6 WAS or hoeing at 3 WAS followed by bispyribac-Na applied 6 WAS. However, highest yields were obtained by hoeing early during the growing season.

Parthenium is a competitive weed spreading in tropical countries. Field experiments were conducted to compare the effect of hand hoeing, growing a smother crop, and applying a herbicide (2,4-D) on parthenium growth and on yield of grain sorghum in smallholder farming systems in eastern Ethiopia. Hand hoeing twice and a smother crop (cowpea) in combination with hand hoeing once consistently suppressed parthenium at the experimental sites. Application of 2,4-D provided inconsistent control of parthenium, possibly because of reemergence from the soil seed bank after control. Growing cowpea as the smother crop suppressed parthenium, but sorghum grain and stalk yields were reduced even when the smother crop was combined with hoeing. Hand hoeing twice, 4 and 8 wk after emergence of sorghum, consistently resulted in better yields than application of 2,4- D and growing smother crop. It is possible that hoeing, apart from controlling the weed, also created better soil conditions for rain water infiltration.