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We present final Spitzer trigonometric parallaxes for 361 L, T, and Y dwarfs. We combine these with prior studies to build a list of 525 known L, T, and Y dwarfs within 20 pc of the Sun, 38 of which are presented here for the first time. Using published photometry and spectroscopy as well as our own follow-up, we present an array of color-magnitude and color-color diagrams to further characterize census members, and we provide polynomial fits to the bulk trends. Using these characterizations, we assign each object a \\(T_{\\rm eff}\\) value and judge sample completeness over bins of \\(T_{\\rm eff}\\) and spectral type. Except for types \\(\\ge\\) T8 and \\(T_{\\rm eff} <\\) 600K, our census is statistically complete to the 20-pc limit. We compare our measured space densities to simulated density distributions and find that the best fit is a power law (\\(dN/dM \\propto M^{-\\alpha}\\)) with \\(\\alpha = 0.6{\\pm}0.1\\). We find that the evolutionary models of Saumon & Marley correctly predict the observed magnitude of the space density spike seen at 1200K \\(< T_{\\rm eff} <\\) 1350K, believed to be caused by an increase in the cooling timescale across the L/T transition. Defining the low-mass terminus using this sample requires a more statistically robust and complete sample of dwarfs \\(\\ge\\)Y0.5 and with \\(T_{\\rm eff} <\\) 400K. We conclude that such frigid objects must exist in substantial numbers, despite the fact that few have so far been identified, and we discuss possible reasons why they have largely eluded detection.

A complete accounting of nearby objects -- from the highest-mass white dwarf progenitors down to low-mass brown dwarfs -- is now possible, thanks to an almost complete set of trigonometric parallax determinations from Gaia, ground-based surveys, and Spitzer follow-up. We create a census of objects within a Sun-centered sphere of 20-pc radius and check published literature to decompose each binary or higher-order system into its separate components. The result is a volume-limited census of \\(\\sim\\)3,600 individual star formation products useful in measuring the initial mass function across the stellar (\\(<8 M_\\odot\\)) and substellar (\\(\\gtrsim 5 M_{Jup}\\)) regimes. Comparing our resulting initial mass function to previous measurements shows good agreement above 0.8\\(M_\\odot\\) and a divergence at lower masses. Our 20-pc space densities are best fit with a quadripartite power law, \\(\\xi(M) = dN/dM \\propto M^{-\\alpha}\\) with long-established values of \\(\\alpha = 2.3\\) at high masses (\\(0.55 < M < 8.00 M_\\odot\\)) and \\(\\alpha = 1.3\\) at intermediate masses (\\(0.22 < M < 0.55 M_\\odot\\)), but at lower masses we find \\(\\alpha = 0.25\\) for \\(0.05 < M <0.22 M_\\odot\\) and \\(\\alpha = 0.6\\) for \\(0.01 < M < 0.05 M_\\odot\\). This implies that the rate of production as a function of decreasing mass diminishes in the low-mass star/high-mass brown dwarf regime before increasing again in the low-mass brown dwarf regime. Correcting for completeness, we find a star to brown dwarf number ratio of, currently, 4:1, and an average mass per object of 0.41 \\(M_\\odot\\).

Stripe rust, or yellow rust (Puccinia striiformis Westend. f. sp. tritic), is a disease of wheat (Triticum aestivum L.) historically causing significant economic losses in cooler growing regions. Novel isolates of stripe rust with increased tolerance for high temperatures were detected in the United States circa 2000. This increased heat tolerance puts geographic regions, such as the soft red winter wheat (SRWW) growing region of the southeastern United States, at greater risk of stripe rust induced losses. In order to identify sources of stripe rust resistance in contemporary germplasm, we conducted genome‐wide association (GWA) studies on stripe rust severity measured in two panels. The first consisted of 273 older varieties, landraces, and some modern elite breeding lines and was evaluated in environments in the U.S. Pacific Northwest and the southeastern United States. The second panel consisted of 588 modern, elite SRWW breeding lines and was evaluated in four environments in Arkansas and Georgia. The analyses identified three major resistance loci on chromosomes: 2AS (presumably the 2NS:2AS alien introgression from Aegilops ventricosa Tausch; syn. Ae. caudata L.), 3BS, and 4BL. The 4BL locus explained a greater portion of variance in resistance than either the 2AS or 3BS loci in southeastern environments. However, its effects were unstable across different environments and sets of germplasm, possibly a result of its involvement in epistatic interactions. Relatively few lines carry resistance alleles at all three loci, suggesting that there is a pre‐existing reservoir of enhanced stripe rust resistance that may be further exploited by regional breeding programs.