No abstract

Meloidogyne arenaria (peanut root-knot nematode (PRKN)) is a major pest of peanut. Nematicide application is an important tool for the management of PRKN. Nematicides with minimal effects on free-living nematodes are desired. Fluopyram nematicide is recently introduced in peanut production and needs to be assessed. The objective of this research is to evaluate fluopyram and the established nematicides 1,3-Dichloropropene (1,3-D) and aldicarb for efficacy at managing PRKN and impacts on free-living nematodes. Nematicides were evaluated in field studies in 2017 and 2018 conducted in commercial peanut fields. All nematicides increased peanut yield in 2017 compared with untreated control, but did not affect soil PRKN abundances or root galling. In 2018, PRKN infestation was too low to accurately assess PRKN management by nematicides. Aldicarb and fluopyram did not affect any free-living nematode trophic group or individual genera. In contrast, 1,3-D decreased total fungivore and fungivore genera Filenchus and Aphelenchus soil abundances, but did not affect bacterivores, omnivore-predators, total herbivores, or any other nematode genera. In summary, 1,3-D, but not aldicarb or fluopyram, had non-target effects on free-living nematodes, particularly fungivores.

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Water-deficit stress is responsible for more crop loss than any other abiotic or biotic stress, resulting in many breeding programmes focusing on developing crop cultivars that can produce relatively greater yield under conditions of water limitation (Borém et al., 2012). Inconsistencies in determining water-deficit tolerant crop ideotypes may result from a lack of understanding or quantification of the coordination between above-and below-ground function of physiological traits. One of the most impactful above-ground functional traits influencing crop yield under water-deficit stress is the degree of transpiration reduction under water-deficit stress (Blum, 2009; de Wit, 1958;Passioura, 1996). The ability to maintain transpiration under dehydrating conditions allows for continued assimilation of CO 2 for photosynthesis, which is required for growth processes. However, the ability to maintain transpiration is linked