McCone County Research Articles

Confirmation of Glyphosate-Resistant Horseweed (Conyza canadensis) in Montana Cereal Production and Response to POST Herbicides

In recent years, horseweed has become an increasing problem in Montana. To confirm and characterize the level of glyphosate resistance, seeds were collected from putative glyphosate-resistant (GR) horseweed (GR-MT) plants in a wheat–fallow field in McCone County, MT. Known GR (GR-NE) and glyphosate-susceptible (GS-NE) horseweed accessions from Lincoln, NE, were included for comparison in dose–response and shikimate accumulation studies. Whole-plant glyphosate dose–response experiments conducted at the early- (5- to 8-cm diameter) and late- (12- to 15-cm diameter) rosette stages of horseweed indicated that GR-MT accessions had a 2.5- to 4.0-fold level of resistance to glyphosate relative to the GS-NE accession, on the basis of shoot dry weight (GR50values). The level of resistance was 3.1- to 7.9-fold on the basis of visually assessed injury estimates (I50values). At the whole-plant level, about 2.1- to 4.5-fold higher shikimate accumulation was observed in the GS-NE accession compared with the GR-MT and GR-NE accessions over a 10-d period after glyphosate was applied at 1,260 g ae ha−1. In a separate greenhouse study, all three horseweed accessions were also screened with alternate POST herbicides registered for use in wheat–fallow rotations. The majority of the tested herbicides provided ≥90% injury at the field-use rates for all three horseweed accessions 3 wk after treatment. This is the first published report on the occurrence of GR horseweed in Montana cereal production. Increased awareness and adoption of best management practices, including the use of diversified (based on multiple sites of action) herbicide programs highlighted in this study, would aid in mitigating the further spread of GR horseweed in the cereal production fields of the U.S. Great Plains.

A Case Study: The Development of Safety Tip Sheets for ATV Use in Ranching

Use of all-terrain vehicles (ATVs) has become standard practice on the modern ranch. The unique operating conditions present on a ranch, subject the occupational ATV user to hazards requiring awareness and specialized training. The purpose of this study was to apply social marketing methods to address a specific environmental health and safety issue present in the agricultural industry. A series of four ATV tip sheets were created in topic areas specific to the challenges that ATV operators encounter on a ranch. In order to evaluate the intended audiences’ perception of the tip sheets, a questionnaire was administered to all agriculture operators and producers throughout McCone County, Montana, USA. Questionnaire responses indicated that the tip sheets contained quality information and were relevant to the occupational hazards present when using ATVs for agricultural purposes. Future work should focus on the dissemination of this information and continued emphasis on industry specific training for ATV operators.

<em>Prodiacodon crustulum</em> (Leptictidae, Mammalia) from the Tullock Member of the Fort Union Formation, Garfield and McCone Counties, Montana, USA

Author(s): Clemens, William A. | Abstract: Since Michael J. Novacek (1977) established Prodiacodon crustulum, the hypodigm of this species has been greatly increased. Currently, over 100 isolated teeth, but only a single dentulous fragment of a dentary, are known. Reconstruction of its dentition has been based on comparisons with the more completely represented dentition of P. puercensis Matthew, 1929, from younger Torrejonian 1-3 North American Land Mammal Age (NALMA) local faunas of the San Juan Basin, New Mexico. Prodiacodon crustulum is known from the Puercan 3 (NALMA) Garbani Channel and, possibly, Purgatory Hill local faunas in Montana. It differs from P. puercensis in the smaller size of its postcanine dentition and lesser development of minor cusps on the upper and lower molars. Given the uncertainties in reconstruction of its dentition, the new sample adds little toward illustrating the phylogenetic relationships of the species to more recent Paleogene and Neogene leptictids. Recent studies support recognition of the clade Leptictida McKenna, 1975, including the leptictids and the Cretaceous species of Gypsonictops Simpson, 1927. More data are needed to test the hypothesis that P. crustulum is the earliest known representative of the Afrotheria Stanhope et al., 1998.

40Ar/39Ar dating and magnetostratigraphic correlation of the terrestrial Cretaceous–Paleogene boundary and Puercan Mammal Age, Hell Creek – Tullock formations, eastern Montana

The recovery and subsequent prolific radiation of mammals in the northern Western Interior of North America following the Cretaceous–Paleogene (K–P) boundary is well documented in rocks attributed to the Puercan Land Mammal Age. The most complete Puercan record is that of the Tullock Formation, which crops out widely in Garfield and McCone counties, eastern Montana. The Tullock Formation overlies the dinosaur-bearing Hell Creek Formation and consists of a stratigraphic series of channel and overbank deposits from which well-preserved Puercan faunas have been collected. These channel deposits are typically bracketed by widespread coal beds. The IrZ- and Z-coals mark the base of the Puercan at the K–P boundary as defined by the highest appearing local occurrences of in situ dinosaur fossils, the highest stratigraphic occurrence of Cretaceous pollen, and an anomalously high concentration of the element iridium (Ir). The IrZ-Coal is overlain sequentially by the Z-, HFZ-, Y-, W-, and U-coals.Fossil vertebrates of earliest Puercan age (Pu0 or Pu1) occur in sandstones of the Hells Hollow Channel between the IrZ-and HFZ-coals in Garfield County and below the Z-Coal in sandstones of the Bug Creek Channels, McCone County. Late Puercan (Pu2/3) fossil vertebrates are abundant between the Y- and W-coals in sandstones of the Garbani Channel in Garfield County, and in sandstones of the Purgatory Hill quarry in McCone County. Earliest Torrejonian (To1?) fossil vertebrates of the Mosquito Gulch localities, Garfield County, occur in sandstones of the Farrand Channel between the W- and U-coals.Magnetostratigraphies developed on sections at Billy Creek, Hauso Flats, Biscuit Butte, Bug Creek, and Purgatory Hill indicate that the IrZ- and Z-coals, the fossil vertebrate-bearing sandstones of the Hells Hollow and Bug Creek channels, and rocks up to midway between the HFZ- and Y-coals are contained in a zone of reversed polarity, correlated here with chron C29r. The Y through W coals, as well as the fossil vertebrate-bearing sandstones of the Garbani Channel and Purgatory Hill, are contained in an overlying zone of normal polarity, correlated with chron C29n. Rocks immediately above the W-Coal through the U-Coal, which include the Farrand Channel, are in a zone of reversed polarity, correlated here with chron C28r. The top of the section, just above the U-Coal, is in the uppermost zone of normal polarity, tentatively correlated here with the base of chron C28n.40Ar/39Ar dating of single crystals of sanidine separated from bentonites in the IrZ-, Z-, HFZ-, W-, and U-coals has yielded high-precision ages with standard errors of 0.1%. Replicate analyses of single crystals of sanidine yield weighted mean ages for bentonites in the following coals: IrZ, 65.16 ± 0.04 Ma; Z, 65.01 ± 0.03 Ma; HFZ, 64.77 ± 0.06 Ma; W, 64.11 ± 0.02 Ma; and U, 63.90 ± 0.04 Ma. These ages provide detailed calibration of Puercan through earliest Torrejonian (PuO, Pu1, Pu2, Pu3, and ?To1) land mammal ages and provide crucial calibration for the nonmarine K–P boundary and the Early Paleogene portion of the geomagnetic polarity time scale.

A new pachycephalosaurid skull (Ornithischia) from the Cretaceous Hell Creek Formation of Montana

ABSTRACT The new genus and species Stenotholus kohleri from the Late Cretaceous Hell Creek Formation of McCone County, Montana is a pachycephalosaurid omithischian. The species possesses a vertically high and transversely narrow dome, elimination of the parietosquamosal shelf, closure of the supratemporal fenestra in the subadult, a highly sculptured frontal, and a sagittally shortened occipital region. The possibility that this skull represents a previously described pachycephalosaurid is rejected on the basis of the unique suite of traits presented.

Dinosaurs from the Paleocene Part of the Hell Creek Formation, McCone County, Montana

Dinosaur remains have been recovered from six localities in the uppermost part of the Hell Creek Formation, McCone County, Montana, which on the basis of stratigraphic placement and contained fossil pollen can be shown to be of Paleocene age. This modifies the argument that an extraterrestrial impact event at the Cretaceous/Tertiary (KIT) boundary caused dinosaur extinction (L. W. Alvarez et al., 1984; Alvarez et al., 1980). The occurrence of dinosaurs in sediments younger than the Cretaceousl Tertiary boundary (Rigby, 1985; Rigby and Sloan, 1985; Sloan et al., 1986; and others) supports the argument that dinosaurs survived the impact event. INTRODUCTION

Kibbey Formation of Montana: ABSTRACT

Laboratory and filed studies of the Kibbey Formation indicate that Kibbey rocks were deposited largely in shallow, marine, oxidizing water in the Big Snowy sea which extended across central Montana during Late Mississippian time. The Siouxia (Transcontinental) arch east of the depositional site supplied most of the detritus for the Kibbey rocks. The climate was semi-arid. Tentatively stable tectonic conditions with moderate to low relief prevailed in the source area throughout Kibbey deposition. The present northern limit of Kibbey rocks is a result of post-Kibbey erosion; the southern limit, although locally determined by erosion, is essentially the depositional limit. Sandstone beds of the Kibbey produce oil in Mussel-shell and McCone Counties, and produced for a short time in Roosevelt County, Montana. Kibbey rocks at all three productive localities appear to have been deposited under very similar environment conditions and in essentially the same position with respect to the axis of the Big Snowy sea. End_of_Article - Last_Page 1571------------