ABSTRACT Peanut smut is an emergent soilborne disease of peanut in South America that has significantly impacted the commercial peanut industry in Argentina. In response, plant breeders are in need of information about potential sources of smut resistance in cultivated germplasm for the rapid development of resistant cultivars. Available U.S. peanut mini-core accessions were evaluated under naturally-infested soil conditions in 2016-2019 near General Cabrera, Córdoba, Argentina, in addition to three susceptible breeding lines and four local commercial controls. Over three years, 18 mini-core accessions and two germplasm collection accessions exhibited no smut incidence in a 100-pod sample. Of those, 12 mini-core accessions and one germplasm collection accession (PI 153323) exhibited no smut incidence when all available pods were opened and examined in the 2016-2017 and 2017-2018 crop years. These 13 accessions were collected from a variety of origins across the Americas, Africa, and Asia; only three were collected from origins in South America. These results suggest that resistance mechanisms may be well-conserved across various groups within Arachis hypogaea L. The 13 identified accessions appear to be sources of resistance to peanut smut in A. hypogaea and would likely be good parent material for the development of new, resistant commercial peanut cultivars.
ABSTRACT Identifying effective weed control regimes for organic peanut is paramount for improving the feasibility of organic production. Tine cultivation is a proven effective method for reducing in-row weed populations in several crops. Field trials were therefore conducted in 2008 and 2009 to assess the effects of tine cultivation combined with sweep cultivation and supplemental hand-weeding on weed control and overall productivity of two peanut cultivars under organic management. Tine cultivation regimes consisted of two frequencies (once per week or twice per week) for three durations (3 wk, 4 wk, or 5 wk). All cultivation treatments were also cultivated with flat sweeps at least once and hand-weeded periodically during the growing season. A non-cultivated, non-weeded control was included for comparison. All cultivation treatments significantly reduced annual grass populations in 2008 and Florida pusley populations both years. Cultivated treatments also resulted in denser plant stands for peanut (9.2 plants/m to 13.2 plants/m) than the non-cultivated control (5.9 plants/m to 7.9 plants/m). Pod yields in cultivated treatments ranged from 3502 kg/ha to 3823 kg/ha and were all significantly greater than yields in the non-cultivated control (1630 kg/ha). Also, net revenues generated by cultivated treatments ranged from ($3333/ha to $3637/ha) and were greater than that of the control ($1795/ha). Cultivation frequency had little effect on weed control and peanut productivity. However, the 4- and 5-wk durations displayed potential for improving peanut yield, grade, and net revenue over the 3-wk duration, especially when annual grass weeds were predominant. Cultivating once weekly for 4 or 5 wk with a tine cultivator, along with at least one sweep cultivation and supplemental hand-weeding, is a viable, economical option for providing adequate weed control and maximizing productivity of organically-managed peanut at current market premiums.