Browsing by Author "Johnson, Greg"

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Monitoring sheep and Culicoides midges in Montana for evidence of Bunyamwera serogroup virus infection
(2014-02) Johnson, Greg; Bahnson, C. S.; Cochrane, Z. N.; Ishii, P.; Hokit, D. G.; Plummer, P. J.; Bartholomay, L. C.; Blitvich, B. J.
Introduction: A serological and entomological investigation was performed to monitor for potential Bunyamwera (BUN) serogroup virus activity in Montana. Results: To facilitate the serological investigation, sera were collected from 104 sheep in 2013 and 2014 and assayed by plaque reduction neutralization test using all six BUN serogroup viruses known to occur in the United States: Cache Valley virus (CVV), Lokern virus (LOKV), Main Drain virus (MDV), Northway virus, Potosi virus and Tensaw virus. BUN serogroup virus-specific antibodies were detected in 41 (39%) sheep. Of these, three were seropositive for MDV, one was seropositive for CVV, one was seropositive for LOKV and 36 had antibodies to an undetermined BUN serogroup virus. Additionally, 30,606 Culicoides sonorensis were collected in 2013 using Centers for Disease Control and Prevention (CDC) light traps and assayed for cytopathic virus by virus isolation in African Green Monkey kidney (Vero) cells. All midges were negative. Almost one-third of the midges were further tested by reverse transcription-polymerase chain reaction using BUN serogroup virus-reactive primers and all were negative. Conclusions: We provide evidence of BUN serogroup virus infection in sheep but not C. sonorensis in Montana in 2013-2014. This study also provides the first evidence of CVV, MDV and LOKV activity in Montana.
Variety Selection and Agronomic Technology to Reduce Heat, Water, and Pest Stress of Canola in Central Montana (2003)
(Central Agricultural Research Center, 2003) Chen, Chengci; Wichman, David M.; Jackson, G.; Johnson, Greg; Neill, Karnes E.; Brown, Jack; Ryerson, Douglas; Johnson, Jim; Vavrovsky, Joe
This paper evaluates selected canola varieties for their adaptation to field sites in north central and central Montana, determines the optimum seeding date and rate to avoid or reduce heat and water stress without risking seedling mortality due to freezing or seed decay in cold soils, and determines the optimum seeding date and rate to avoid or reduce pest damage. Fourteen varieties and breeding lines, including regular and Clear-Field canola, were obtained from Dr. Jack Brown’s canola breeding program at University of Idaho, and three Roundup-Ready canola varieties were received from Monsanto Company and Interstate Seed Company. The canola was planted at the Central Agricultural Research Center of Montana State University, Moccasin, MT on May 30, 2003 in a tilled re-cropped field. The experiment was a randomized complete block design with four replications. The seeding rate (plant density) was 67 plants m-2. Fertilizer was applied after the canola grew to two true leaves stage at a rate of 75 kgN and 25 kgP2O5 per hectare using the broadcast method. Because of the delayed seeding (seeds arrived late) in conjunction with a severe summer drought, the experiment was a disaster. The drought during flowering and seed filling stages severely reduce canola yield. The seed yield was less than 40 kg ha-1 in this study (Table 1). Due to the severe summer drought, canola yield in 2003 was much lower than in 2002. Early seeding continued to receive higher yields than late seeding.
Variety Selection and Agronomic Technology to Reduce Heat, Water, and Pest Stress of Canola in Central Montana (2004)
(Central Agricultural Research Center, 2004) Chen, Chengci; Wichman, David M.; Jackson, G.; Johnson, Greg; Neill, Karnes E.; Rolston, Marni G.; Brown, Jack; Ryerson, Douglas; Johnson, Jim
This paper evaluates selected canola varieties for their adaptation to field sites in north central and central Montana; determines the optimum seeding date and rate to avoid or reduce heat and water stress without risking seedling mortality due to freezing or seed decay in cold soils; and determines the optimum seeding date and rate to avoid or reduce pest damage. Fourteen varieties and breeding lines, including regular and Clear-Field canola, were obtained from Dr. Jack Brown’s canola breeding program at University of Idaho, and three Roundup-Ready canola varieties were received from Monsanto Company and Interstate Seed Company. The canola was planted at the Central and Western Triangle Agricultural Research Centers (CARC and WTARC) of Montana State University. Canola seed yield is significantly affected by seeding date and rate. Early seeding date is a key for obtaining a high and stable yield. Canola should be seeded in late March to early April with a seeding rate of 33 to 67 plants m-2 in central and north central Montana. Several breeding lines from Dr. Jack Brown’s breeding program at University of Idaho showed promising in yield and oil content. However, selected cultivars for early seeding in Montana must be able to emerge in cool soils and tolerate frequent frost damages in early spring. Our preliminary study in variety evaluation and cold tolerance screening showed promising results (Table 2). Therefore, I ask the PNW Canola Research Program Committee to continue supporting my research on variety evaluation and cold tolerance screening.