Research Notes : United States : Resistance to anthracnose

Anthracnose, caused by Colletotrichum dematium (Pers. ex Tr.) Grove var. truncatum (Sahw.) Arx., can be found in most U.S. soybean producing areas. It is the most prominent disease in much of the southern U.S. and for the Texas Gulf Coast. In recent years, estimates of yield losses caused by anthracnose in the southern U.S. have exceeded 28 million bushels per year, a 2.5% loss in potential yield (Sturgeon, 1980)

Proceedings of the 21st Annual Meeting, Southern Soybean Disease Workers (March 6-8, 1994, Tulsa, Oklahoma)

Contents 1993-94 SSDW Committee Chairs 1993-94 SSDW Officers Graduate student competition Resistance of Soybean Cultivars in Maturity Group IV-VIII to Rotylenchulus reniformis. JJ Cornelius and GW Lawrence Evaluation of Susceptibility of Soybean to Red Crown Rot caused by Calonectria crotalariae in the Field. KD Kim, JS Russin, and JP Snow Contributed papers Soybean Disease Loss Estimate for the Southern United States During 1993, Table 1. Estimated percent Joss of soybean yields in 1993 to disease, Table 2. Estimated reduction of soybean yields in 1993 to disease, and Table 3. Southern states soybean disease loss estimate total in bushels and dollars, 1993. Compiled by JA Wrather Aerial Blight Associated with Delayed Maturity of Soybean. IA Fox, MA Blaine, and GL Sciumbato Relationship of Phytophthora Resistance to Soybean Yield. GL Sciumbato., FG Hancock, JA Fox, and D Boykin Effects of Long-Term Tillage Practices on Soil Populations of Microsclerotia of Macrophomina phaseolina. SR Kendig and JA Wrather Effect of Maturity Group, Growth Stage, and Planting Date on Progress of Sudden Death Syndrome of Soybean. JC Rupe and EE Gebur, Jr Additional Soybean Plant Introductions Resistant to Soybean Cyst Nematode. LD Young Frogeye Leaf Spot Control in Soybeans with Foliar-Fungicides. AY Chambers Interaction of the Root-Knot Nematode, Meloidogyne incognita, with Selected Weed Species Present in Soybean Fields in Louisiana. EC McGawley, JS Russin, and JL Griffin Population Development by Meloidogyne incognita and Heterodera glycines on Soybean Stressed by Weeds and Defoliation. JS Russin, EC McGawley, and LL Griffin Resistance to Rotylenchulus reniformis in Soybean. RT Robbins and L Rakes Treasurer\u27s report. GG Hammes Proceedings of the Southern Soybean Disease Workers are published annually by the Southern Soybean Disease Workers. Text, references, figures, and tables are reproduced as they were submitted by the authors. The opinions exposed by the participants at this conference are their own and do not necessarily represent the views of the Southern Soybean Disease Workers. Mention of trademark or propriety products in this Proceedings does not constitute a guarantee, warranty, or endorsement of that product by the Southern Soybean Disease Workers

Proceedings of the 19th Annual Meeting, Southern Soybean Disease Workers (February 19-20, 1992, St. Louis, Missouri)

Contents Southern Soybean Disease Workers 1991-1992 officers 1991-1992 Program Committee Graduate student competition Interactions of Macrophomina phaseolina with two soybean cultivars under four irrigation regimes. SR Kendig and JC Rupe Influence of soybean planting dates on the incidence and severity of Sudden Death Syndrome. SS Alghamdi, PT Gibson, and MA Shenaut The interrelationship of Heterodera glycines and Fusarium solani in sudden death syndrome of soybean. KS McLean and GW Lawrence Frogeye leaf spot of soybean: evaluation of cultivars and isolates. PF Pace, DB Weaver, and LD Ploper Soybean cyst nematode race symposium SCN race scheme: a historical perspective. JA Fox Races of Heterodera glycines: a nematological perspective. TL Niblack Races of Heterodera glycines and level of resistance in soybean cultivars. SC Anand Differentiating soybean responses to soybean cyst nematode races. DP Schmitt and JG Shannon Strategies for improved soybean yields and profits in the Southern US. JH Palmer Contributed papers Evaluation of resistance to Rhizoctonia Foliar Blight of soybean. CS Kousik, GB Padgett, JP Snow, and BG Harville Five years of soybean variety testing for SDS response. PT Gibson, M Schmidt, MA Shenaut, and O Myers, Jr Effect of tillage, planting date, and cultivar on the severity of sudden death syndrome, Septoria brown spot and downy mildew of soybean. JA Wrather, TL Niblack, GS Smith, and SC Anand Effect sof soybean planting date on severity of stem canker. AY Chambers Comparative virulence of stem canker isolates from southern soybean growing areas. GL Sciumbato and BL Keeling Effects of a low rate of aldicarb on soybean canopy development and yield, weed and insect populations in Heterodera glycines-infested fields. SR Koenning, KR Barker, HD Coble, and JR Bradley Effect of soybean cyst nematode on soybean isolines differing for maturity. WJ Wiebold and TL Niblack Effect of repeated application of selected herbicides and nematicides/insecticides on soybean cyst nematode density. P Donald, A Keaster, R Kremer, and B Sims Southern United States soybean disease loss estimate for 1991. Southern Soybean Disease Workers, Soybean Disease Loss Estimate Committee. Compiled by GL Sciumbato and DL Turnage SSDW Treasurer\u27s report. GG Hammes Southern Soybean Disease Workers 1990-1991 committee chairmen Southern Soybean Disease Workers 1991 award recipients Proceedings of the Southern Soybean Disease Workers is published annually by the Southern Soybean Disease Workers. Text, references, figures, and tables are reproduced as they were submitted by the author(s). The opinions expressed by the participants at this conference are their own and do not necessarily represent the views of the Southern Soybean Disease Workers. Mention of trademark or propriety product in this Proceedings does not constitute a guarantee, warranty, of endorsement of that product by the Southern Soybean Disease Workers

The Bolocam Galactic Plane Survey. XII. Distance Catalog Expansion Using Kinematic Isolation of Dense Molecular Cloud Structures With 13CO(1-0)

We present an expanded distance catalog for 1,710 molecular cloud structures identified in the Bolocam Galactic Plane Survey (BGPS) version 2, representing a nearly threefold increase over the previous BGPS distance catalog. We additionally present a new method for incorporating extant data sets into our Bayesian distance probability density function (DPDF) methodology. To augment the dense-gas tracers (e.g., HCO+(3-2), NH3(1,1)) used to derive line-of-sight velocities for kinematic distances, we utilize the Galactic Ring Survey 13CO(1-0) data to morphologically extract velocities for BGPS sources. The outline of a BGPS source is used to select a region of the GRS 13CO data, along with a reference region to subtract enveloping diffuse emission, to produce a line profile of 13CO matched to the BGPS source. For objects with a HCO+(3-2) velocity, \approx 95% of the new 13CO(1-0) velocities agree with that of the dense gas. A new prior DPDF for kinematic distance ambiguity (KDA) resolution, based on a validated formalism for associating molecular cloud structures with known objects from the literature, is presented. We demonstrate this prior using catalogs of masers with trigonometric parallaxes and HII regions with robust KDA resolutions. The distance catalog presented here contains well-constrained distance estimates for 20% of BGPS V2 sources, with typical distance uncertainties \lesssim 0.5 kpc. Approximately 75% of the well-constrained sources lie within 6 kpc of the Sun, concentrated in the Scutum-Centarus arm. Galactocentric positions of objects additionally trace out portions of the Sagittarius, Perseus, and Outer arms in the first and second Galactic quadrants, and we also find evidence for significant regions of interarm dense gas.Comment: 28 pages, 19 figures. Accepted for publication in ApJ. Distance-Omnibus code available at https://github.com/BGPS/distance-omnibu

The Bolocam Galactic Plane Survey. XIII. Physical Properties and Mass Functions of Dense Molecular Cloud Structures

We use the distance probability density function (DPDF) formalism of Ellsworth-Bowers et al. (2013, 2015) to derive physical properties for the collection of 1,710 Bolocam Galactic Plane Survey (BGPS) version 2 sources with well-constrained distance estimates. To account for Malmquist bias, we estimate that the present sample of BGPS sources is 90% complete above 400 $M_\odot$ and 50% complete above 70 $M_\odot$. The mass distributions for the entire sample and astrophysically motivated subsets are generally fitted well by a lognormal function, with approximately power-law distributions at high mass. Power-law behavior emerges more clearly when the sample population is narrowed in heliocentric distance (power-law index $\alpha = 2.0\pm0.1$ for sources nearer than 6.5 kpc and $\alpha = 1.9\pm0.1$ for objects between 2 kpc and 10 kpc). The high-mass power-law indices are generally $1.85 \leq \alpha \leq 2.05$ for various subsamples of sources, intermediate between that of giant molecular clouds and the stellar initial mass function. The fit to the entire sample yields a high-mass power-law $\hat{\alpha} = 1.94_{-0.10}^{+0.34}$. Physical properties of BGPS sources are consistent with large molecular cloud clumps or small molecular clouds, but the fractal nature of the dense interstellar medium makes difficult the mapping of observational categories to the dominant physical processes driving the observed structure. The face-on map of the Galactic disk's mass surface density based on BGPS dense molecular cloud structures reveals the high-mass star-forming regions W43, W49, and W51 as prominent mass concentrations in the first quadrant. Furthermore, we present a 0.25-kpc resolution map of the dense gas mass fraction across the Galactic disk that peaks around 5%.Comment: Accepted for publication in ApJ; 32 pages, 21 figure

The Bolocam Galactic Plane Survey IX: Data Release 2 and Outer Galaxy Extension

We present a re-reduction and expansion of the Bolocam Galactic Plane Survey, first presented by Aguirre et al. (2011) and Rosolowsky et al. (2010). The BGPS is a 1.1 mm survey of dust emission in the Northern galactic plane, covering longitudes -10 < \ell < 90 and latitudes |b| < 0.5 with a typical 1-\sigma RMS sensitivity of 30-100 mJy in a 33" beam. Version 2 of the survey includes an additional 20 square degrees of coverage in the 3rd and 4th quadrants and 2 square degrees in the 1st quadrant. The new data release has improved angular recovery, with complete recovery out to 80" and partial recovery to 300", and reduced negative bowls around bright sources resulting from the atmospheric subtraction process. We resolve the factor of 1.5 flux calibration offset between the v1.0 data release and other data sets and determine that there is no offset between v2.0 and other data sets. The v2.0 pointing accuracy is tested against other surveys and demonstrated to be accurate and an improvement over v1.0. We present simulations and tests of the pipeline and its properties, including measurements of the pipeline's angular transfer function. The Bolocat cataloging tool was used to extract a new catalog, which includes 8594 sources, with 591 in the expanded regions. We have demonstrated that the Bolocat 40" and 80" apertures are accurate even in the presence of strong extended background emission. The number of sources is lower than in v1.0, but the amount of flux and area included in identified sources is larger.Comment: 36 pages, 16 figures, accepted to ApJS. Data available from http://irsa.ipac.caltech.edu/data/BOLOCAM_GPS

The Bolocam Galactic Plane Survey. XIV. Physical Properties of Massive Starless and Star Forming Clumps

We sort $4683$ molecular clouds between $10^\circ< \ell <65^\circ$ from the Bolocam Galactic Plane Survey based on observational diagnostics of star formation activity: compact $70$ $\mu{\rm m}$ sources, mid-IR color-selected YSOs, ${\rm H_2O}$ and ${\rm CH_3OH}$ masers, and UCHII regions. We also present a combined ${\rm NH_3}$-derived gas kinetic temperature and ${\rm H_2O}$ maser catalog for $1788$ clumps from our own GBT 100m observations and from the literature. We identify a subsample of $2223$ ($47.5\%$) starless clump candidates, the largest and most robust sample identified from a blind survey to date. Distributions of flux density, flux concentration, solid angle, kinetic temperature, column density, radius, and mass show strong ($>1$ dex) progressions when sorted by star formation indicator. The median starless clump candidate is marginally sub-virial ($\alpha \sim 0.7$) with $>75\%$ of clumps with known distance being gravitationally bound ($\alpha < 2$). These samples show a statistically significant increase in the median clump mass of $\Delta M \sim 170-370$ M$_\odot$ from the starless candidates to clumps associated with protostars. This trend could be due to (i) mass growth of the clumps at $\dot{M}\sim200-440$ Msun Myr$^{-1}$ for an average free-fall $0.8$ Myr time-scale, (ii) a systematic factor of two increase in dust opacity from starless to protostellar phases, (iii) and/or a variation in the ratio of starless to protostellar clump lifetime that scales as $\sim M^{-0.4}$. By comparing to the observed number of ${\rm CH_3OH}$ maser containing clumps we estimate the phase-lifetime of massive ($M>10^3$ M$_\odot$) starless clumps to be $0.37 \pm 0.08 \ {\rm Myr} \ (M/10^3 \ {\rm M}_\odot)^{-1}$; the majority ($M<450$ M$_\odot$) have phase-lifetimes longer than their average free-fall time.Comment: Accepted for publication in ApJ; 33 pages; 22 figures; 7 table

The Bolocam Galactic Plane Survey. VIII. A Mid-Infrared Kinematic Distance Discrimination Method

We present a new distance estimation method for dust-continuum-identified molecular cloud clumps. Recent (sub-)millimeter Galactic plane surveys have cataloged tens of thousands of these objects, but detailed study of their physical properties requires robust distance determinations. We derive Bayesian distance probability density functions (DPDFs) for 770 objects from the Bolocam Galactic Plane Survey in the longitude range 7.5 < l < 65. The DPDF formalism is based on kinematic distances, and uses external data sets to place prior distance probabilities to resolve the kinematic distance ambiguity (KDA) for objects in the inner Galaxy. We present priors related to the mid-infrared absorption of dust in dense molecular regions and the Galactic distribution of molecular gas. By assuming a numerical model of Galactic mid-infrared emission and simple radiative transfer, we match the morphology of millimeter thermal dust emission with mid-infrared absorption to compute a prior DPDF for distance discrimination. Selecting objects first from (sub-)millimeter source catalogs avoids a bias towards the darkest infrared dark clouds (IRDCs) and extends the range of heliocentric distance and contrast range probed by mid-infrared extinction. We derive well-constrained KDA resolutions for 618 molecular cloud clumps, with approximately 15% placed at or beyond the tangent distance. Objects sufficiently dark to be cataloged as IRDCs are generally placed at the near kinematic distance. Distance comparisons with Galactic Ring Survey KDA resolutions yield a 92% agreement, and a Galactic face-on view reveals sections of the Sagittarius and Scutum-Centaurus Arms. This KDA-resolution method for large catalogs of sources through the combination of (sub-)millimeter and mid-infrared observations of molecular cloud clumps is generally applicable to other dust-continuum Galactic plane surveys.Comment: Accepted for publication in ApJ; 29 pages, 16 figures. Data available prior to publication by contacting the author