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We provide APASS photometry in the Landolt BV and Sloan g'r'i' bands for all the 425,743 stars included in the latest 4th RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as error of the mean of data obtained and separately calibrated over a median of 4 distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014 and 0.021 mag for B, V, g', r' and i' band, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process, and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been chi2 fitted to a densely populated synthetic photometric library designed to widely explore in temperature, surface gravity, metallicity and reddening. Resulting Teff and E(B-V), computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process it is found that the reddening caused by an homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for E(B-V,poles)=0.036 +/- 0.002 at the galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b|>=25 deg., Comment: Astronomical Journal, in press. Resolution of Figures degrated to match arXiv file size limits

We have made high-resolution, high-sensitivity dynamic spectra of a sample of strong pulsars at 430 MHz with the Arecibo radiotelescope. For 4 pulsars we find faint but sharply delineated features in the secondary spectra. These are examples of the previously observed ``crisscross'' or ``multiple drift slope'' phenomenon presumed to be due to multiple imaging of the pulsar by the interstellar medium. The unprecedented resolution and dynamic range of our observations allow a deeper level of analysis. Distances to the dominant scattering screen along the line of sight are determined and are shown to agree well with those inferred from other scintillation phenomena. Multiple imaging of the pulsar by the ISM is required. A compact central image surrounded by a faint scattering halo, roughly circularly symmetric, is consistent with the data. Scattering from filaments may also be consistent. The angular extent of the scattering material parallel to the direction of the pulsar velocity is roughly 5 mas, corresponding to a linear extent of about 2 AU. Further observations of these features should allow better discrimination between models and an identification of the scattering structures., Comment: 4 pages, 3 jpg figures, accepted by ApJ Letters

In U. S. cotton production systems, Palmer amaranth [Amaranthus palmeri (S.) Wats.] is the most problematic weed and can reduce yield and harvest efficiency. Palmer amaranth emerges and thrives in cotton, where canopy closure is prolonged relative to other row-crops grown in the mid-South. In 2018, at the University of Arkansas System Division of Agriculture's Lon Mann Cotton Research and Extension Station near Marianna, Arkansas, a trial was initiated to evaluate the long-term implications of integrated weed management strategies on Palmer amaranth emergence. The experiment took place over four years with plots located in the same test site. The experiment consisted of 16 treatments with 4 replications comparing multiple weed management strategies alone and in combination: deep tillage, a cereal rye cover crop, zero-tolerance, and a dicamba-based weed control program or a standard glufosinate program. Averaged over the first four years of the study, using zero tolerance, a cereal rye cover crop, or a plow event reduced Palmer amaranth emergence by 56%, 58%, and 63%, respectively. When a plow event was combined with a dicamba-based herbicide program or when a plow event, a dicamba-based program, and cover crop were utilized, Palmer amaranth emergence was reduced by 93%. Using a plow event plus a dicamba-based herbicide program or using a one-time plow event in combination with a dicamba-based program and a cover crop had the greatest reduction of Palmer amaranth emergence over the four-year period. [ABSTRACT FROM AUTHOR]

John Deere recently announced the commercial release of See & Spray™ Ultimate, which facilitates precision herbicide applications in row crops. Currently, no published literature exists detailing the performance of this new technology in cotton production systems or the ability of the system to detect weeds through cover crop canopy. Research was conducted at the University of Arkansas System Division of Agriculture's Northeast Research and Extension Center to evaluate See & Spray Ultimate's performance with a fallow, cereal rye, and hairy vetch cover crop system in XtendFlex® cotton. The experiment evaluated a dual-tank and a single-tank See & Spray program versus a broadcast standard with consistent herbicide rates across preemergence (PRE), early-postemergence (EPOST), and mid-postemergence (MPOST) herbicide programs. The See & Spray single-tank program was the only application method to cause a slight reduction in Palmer amaranth (Amaranthus palmeri S. Wats.) control from 98% with the broadcast standard to 94% 14 days after the EPOST application. Additionally, Palmer amaranth control improved from 95% with no cover crop to 98% with a cereal rye cover crop. By 14 days after the MPOST, all application methods and cover crop systems were comparable. By the end of the season, cover crops were the only factor to influence yield, whereas cotton without a cover crop yielded better than with cover crops. Results from this research indicate that See & Spray Ultimate can be utilized with cover crops in cotton, but the machine was operated with a medium sensitivity setting (level 4), and herbicide savings and weed control with this technology will likely vary with different sensitivity settings. [ABSTRACT FROM AUTHOR]

In United States' cropping systems, Palmer amaranth has become one of the most troublesome weeds, particularly in slow canopying crops such as cotton. A long-term field trial was initiated at the University of Arkansas System Division of Agriculture's Lon Mann Cotton Research and Extension Center, Marianna, Arkansas, to assess the impact of cultural and mechanical weed management strategies on Palmer amaranth over a three-year period. Non-chemical approaches such as tillage, cover cropping with cereal rye, and zero-tolerance were evaluated in combination with two standard weed control systems, one with dicamba used preemergence (PRE) and early postemergence (POST) compared to a program with no dicamba herbicide. The experiment was organized in a randomized complete block design with 16 treatments and four replications. Results showed that adopting a cover crop reduced weed emergence by 82%. The use of the zero-tolerance approach plus dicamba and non-dicamba herbicides showed comparative results, both causing a 63% reduction in Palmer amaranth emergence. A 37% reduction was observed in treatments that included tillage, but statistically, no difference was observed compared to treatments lacking tillage. The adoption of zero-tolerance with dicamba and non-dicamba herbicides plus the use of a cover crop (cereal rye) had a high impact on reducing the number of Palmer amaranth seedlings emerging throughout the trial. In the battle against herbicide resistance, the combination of multiple weed control practices (chemical, cultural, mechanical, and others) is essential to manage resistant weed populations and maintain sustainable cotton production. [ABSTRACT FROM AUTHOR]

Soybean [Glycine max (L.) Merr.] cropping systems are an essential part of agriculture in the United States. Palmer amaranth [Amaranthus palmeri (S.) Watson] is one of the most troublesome weeds in these systems and can reduce yields for producers. Herbicide resistance has posed new obstacles to controlling Palmer amaranth. Methods such as mechanical seed destruction can add another option for producers to combat this troublesome weed. Field trials were initiated at both the University of Arkansas System Division of Agriculture's Jackson County Extension Center located near Newport, Arkansas, and the Northeast Research and Extension Center located in Keiser, Arkansas, to assess how desiccation of soybean infested with Palmer amaranth affects shattering of the weed and the effectiveness of a Redekop™ seed destructor. Treatments of 5 different desiccants were applied to plots, and plots were then split with harvest weed seed control and no harvest weed seed control being the subplot factor. Results showed that harvest weed seed control significantly reduced the number of viable seeds returning to the soil seed bank by 60% at the Keiser location and 64% at the Newport location. Treatment and the interaction between treatment and harvest weed seed control were insignificant. With Palmer amaranth resistance making it harder to control, using methods such as a Redekop seed destructor as a harvest weed seed control tactic can help combat the growing problem. [ABSTRACT FROM AUTHOR]

The ROXY® Rice Production System (RRPS) was recently commercialized in California, allowing producers to apply oxyfluorfen (HRAC/WSSA Group 14) both preemergence and postemergence. The use of oxyfluorfen in the RRPS provides producers with an additional herbicide option for barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] control in rice (Oryza sativa L.). A field experiment was conducted at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center near Stuttgart, Ark., in 2022, to evaluate residual barnyardgrass control with clomazone and oxyfluorfen alone and in mixture. Herbicide treatments included clomazone at 0.25 or 0.3 lb ai/ac, and oxyfluorfen at 0.6 or 0.75 lb ai/ac applied preemergence followed by a sequential postemergence application. A 1:2 and 1:3 ratio of clomazone and oxyfluorfen (0.3 + 0.6 lb ai/ac and 0.25 + 0.75 lb ai/ac) were also evaluated. At 3 weeks after the preemergence application, but prior to the postemergence application, all rates of oxyfluorfen and clomazone alone provided =94% visual control of barnyardgrass. All combinations of clomazone and oxyfluorfen, provided 100% barnyardgrass visual control at 3 weeks after the preemergence application. At 5 weeks after the postemergence application, all treatments provided = 94% barnyardgrass control. At 6 weeks after the postemergence application, mixtures of clomazone and oxyfluorfen provided 95% or greater barnyardgrass control. Conversely, when sequential applications of oxyfluorfen alone were made, regardless of rate, barnyardgrass control was only 77% and 79% at 6 weeks after the postemergence application. When clomazone and oxyfluorfen were applied at a 1:3 ratio and 1:2 ratio or clomazone alone applied at 0.3 lb ai/ac, rice yields were comparable among treatments, ranging from 106 to 130 bu./ac. Treatments of oxyfluorfen at 0.6 and 0.75 lb ai/ac, and clomazone at 0.25 lb ai/ac, resulted in rice yields of 74 to 93 bu./ac. These results indicate that clomazone will likely be needed with oxyfluorfen to obtain extended residual barnyardgrass control in the RRPS. [ABSTRACT FROM AUTHOR]