• Alfalfa Varieties from the 1920s to the 1980s: Comparison of Forage Yield During the Seedling Year

      Smith, S. E.; Conta, D. M.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • Evaluation of the Accuracy of a Wheat Stem Nitrate Test in Predicting Nitrogen Requirements of Irrigated Durum Wheat

      Doerge, T.; Knowles, T.; Ottman, M.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      The procedure currently recommended by the University of Arizona for predicting the nitrogen (N) requirements of durum wheat has proven to be quite accurate at sites where grain yields exceeded 5,400 lbs/acre. However, the method slightly overestimated N needs when the yield possibility was below that level. Additional information on the relationships between N rates, stem NO₃⁻N levels and grain yields are needed for the wide range of agronomic conditions found in Arizona. Three N fertility trials were conducted at the Maricopa Agricultural Center to: 1) document the accuracy of the currently recommended soil + stem NO₃⁻N testing procedure in predicting the N needs of durum wheat on soils of varying residual N content and grain yield potentials; and 2) to evaluate the use of the current stem testing procedure on two durum varieties 'Aldura' and 'Westbred -881. The University of Arizona procedure was found to accurately predict the minimum amount of N required for optimum production of durum wheat on two sites where yield potentials were 5,400 and 4300 lbs. grain /A, but it slightly overpredicted N rates on two sites with maximum yield levels of 5,400 lbs /a. 'Aldura' consistently out yielded 'Westbred -881' by about 12 % but 'Aldura' also averaged 0.78 %lower in grain protein content. Little statistical or practical differences were observed in the quantities of NO₃⁻N contained in the stem tissue of these two varieties, which should simplify the interpretation of stem NO₃⁻N values for various wheat cultivars. The currently recommended procedure for predicting optimum N rates in durum wheat production has proven to be accurate when yield levels exceed 5,400 lbs. grain /A. A slight modification of the procedure may be needed to more closely predict N requirements on lower yielding sites.
    • Stomate Density and Physiological Measurements on Leaves of Alkali Sacaton

      Dobrenz, A. K.; Cox, J.; Munda, B.; Robinson, D.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • Effects of Salinity on the Water Potential of Alfalfa Seedlings

      McKimmie, T.; Dobrenz, A. K.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Alfalfa seedlings were grown under saline conditions for six weeks and separated into two populations, based on height. Water potential was measured on roots, stems, leaves, and petioles of tall and short plants. Tall plants had a higher water potential for each plant part.
    • Small Grain Variety Comparisons at the Maricopa Agricultural Center, 1988

      Sheedy, M.; Ottman, M.; Ramage, T.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • The Effects of Alfalfa Seed Scarification in Saline Environments

      Poteet, D. C.; Robinson, D. L.; Dobrenz, A. K.; Smith, S. E.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      The handling of alfalfa and other crop seed may result in seed scarification. Scarification may not affect germination of alfalfa seed in a non - saline environment, but may decrease germination where farmer's fields are severely salt-stressed.
    • The Role of Cercospora Summer Black Stem and Leaf Spot in the Alfalfa Decline Problem in La Paz County

      Matheron, M.; Winans, S.; Matejka, J.; Rethwisch, M.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      An alfalfa decline problem has appeared recently in fields between Poston and Parker in La Paz County. Cercospora summer black stem and leaf spot, a fungal disease of alfalfa, has been associated with the decline problem. The efficacy of three fungicides were tested for control of the disease and the decline problem. Bravo, Kocide, and Spotless significantly reduced the severity of Cercospora summer black stem and leaf spot; however, significant increases in yield were not realized. Alfalfa decline in La Paz County may involve other factors in addition to plant disease.
    • Oat Variety Trial in Cochise County, 1988

      Clark, L. J.; Schwennesen, E.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Ten varieties of oats were grown in a trial to test grain yield. Five of the varieties produced more than 4,000 pounds per acre; the top - yielding variety, Ogle, from Minnesota, produced 4,578 pounds per acre. Difficulties in establishing a perfect stand with the small plot grain drill would probably mean that a farmer could expect yields higher than these when using full -sized equipment. Considering the premium for oats, oats for grain could be a viable alternative crop.
    • Evaluation of Plant Growth Regulators on Wheat in Arizona, 1987

      Tickes, B.; Ottman, M. J.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Plant growth regulators are applied to small grains to decrease lodging which can adversely affect crop growth and yield. Wheat is intensively managed in Arizona, and lodging can be a problem. Chlormequat and ethephon were applied at various rates and times in six studies in 1987 to evaluate their use on Arizona's semi -dwarf cultivars with respect to lodging plant height, yield components and grain yield The results indicated that growth regulators applied at the recommended rates and times may decrease plant height and decrease kernel weight. However, the influence of growth regulator treatments on tiller number, head number, kernel number, and grain yield was not demonstrated. The ambiguous results obtained suggest our efforts need to be directed toward documenting the extent of lodging in the state, studying the effects of lodging and predicting when lodging will occur.
    • Corn Variety Trial in Greenlee County, 1987

      DeRosa, E.; Clark, L.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Fifteen varieties of about 125+ day corn hybrids were tested in an ongoing variety trial in Greenlee County.
    • Double Crop Grain Sorghum Variety Trial in Graham County, 1987

      Clark, L. J.; Cluff, R. E.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      1987 was a better year for double -crop grain sorghum than the previous year. The yields increased to nearly a ton per acre. The top - yielding variety was Asgrow Topaz at 7,885.7 pounds per acre. This yield topped the standard variety, DeKalb 64 by almost 4 percent. Bird damage was also reduced this year.
    • Barley Variety Trial in Cochise County, 1988

      Clark, L. J.; Schwennesen, E.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Eight barley varieties were tested in a replicated variety trial in northern Cochise county. These varieties varied from relatively early maturing varieties, such as Barcot4 to the longer maturing varieties, such as Gustoe. The medium -late variety, Northrup King 1558, was the top - yielding variety, with 7,185 pounds per acre. This exceeded the yield of the standard variety, Gustoe, by 15 percent, making NK 1558 a variety that should be looked at further. It will be marketed by Northrup King under the name Sunbar 458.
    • Seeding Rate and Row Spacing for WestBred 881 and Aldura Durum at Marana, 1988

      Ottman, M. J.; Day, A. D.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      WestBred 881 durum commands a premium price due to its superior quality, but it produces a lower yield than other commonly grown cultivars. This study was initiated to improve our understanding of how to grow WestBred 881. Two dumm cultivars (WestBred 881 and Aldura) were planted at five seeding rates (30, 60, 120, 180, and 240 lbs seed /A) and five row spacings (3, 6, 12, 18 an 24 inches) at the Marana Agricultural Center. The optimum seeding rate was 180 lbs /A for WestBred 881 and 120 lb /A for Aldura. An increase in seeding rate resulted in decreased kernel weight and number and increased head number. At row spacings of 3, 6 and 12 inches, grain yield of WestBred 881 was 6120, 6300, and 6060 lbs /A and grain yield of Aldura was 6350, 6770, and 7190 lb /A, respectively. WestBred 881 has larger kernels than Aldura but fewer kernels per head and heads per unit area. The yield advantage of WestBred 881 relative to Aldura at higher seeding rates was due to in kernels per head. At the closer row spacings, the advantage was due to kernel weight, kernels per head and heads per unit area.
    • Effect of Russian Wheat Aphid on Durum Wheat Yield

      Dick, G.; Harper, J.; Moore, L.; Ottman, M.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • Oat Varieties Grown for Grain and Forage Production at the Safford Agricultural Center, 1988

      Clark, L. J.; Carpenter, E. W.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      Eleven oat varieties were tested for grain and forage yields at the Safford Agricultural Center. Cayuse, the predominant variety grown in the area was the top producer of total dry matter. Four other varieties had higher grain yields than Cayuse.
    • Cultural Practices of One-Irrigation Barley at Marana, 1988

      Ottman, M. J.; Ramage, R. T.; Thacker, G. W.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      One-irrigation barleys were bred to be grown with only a single irrigation near planting time. To further our understanding of how to manage these new cultivars, two one - irrigation barley genotypes (Seco and 2 -22 -9) were grown at four seeding rates (20, 40, 60, and 80 lbs seed /A); four nitrogen rates (0, 50, 100, and 150 lbs N /A); two phosphorus rates (0 and 100 lbs P₂O₅ /A); four row spacings (6, 12, 18, and 24 inch); and three planting dates (Nov 19, Dec. 23, and Jan. 22). The optimum seeding rate, fertilizer rate, and row spacing were dependent on genotype and planting date. The optimum seeding rate was 40 to 60 lbs /A for Seco and 80 lbs /A for 2 -22 -9. An increase in seeding rate decreased kernel weight and kernel number per head but increased head number. A positive response to nitrogen fertilizer was not obtained due to the high levels of residual soil nitrogen at planting (20 ppm NO₃⁻N) except for the case of Seco at the Dec. 23 planting date. Phosphorus fertilizer increased yield only at the Nov. 19 planting date and if accompanied by 100 lbs N /A. Soil phosphorous levels were 2 ppm PO₄⁻P and a positive response was expected Kernel weight was not influenced by Nor P fertilizer. Kernel number per head increased with certain combinations of genotype and planting date. Head number decreased with N rate but increased with phosphorus. The optimum row spacing was 18 inches at the Nov. 19 planting and 12 inches for Seco at the Jan. 22 planting date. At other combinations of genotype and planting date, no differences in grain yield were detected due to row spacing. Kernel weight increased with row spacing at the Nov. 19 planting date; kernel number per head was generally not affected and, head number decreased with row spacing. The results of this study surest that any recommendations on how to grow one - irrigation barley are gross approximations because of variations due to year, planting date, and genotype.
    • Breeding Strategies for Alfalfa Grown Under Saline Conditions

      Johnson, D. W.; Smith, S. E.; Dobrenz, A. K.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
    • Corn Variety Trial in Bonita, Cochise County, 1987

      Clark, L. J.; Schwennesen, E.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      The 1987 trials included 14 commercial corn hybrids, which were tested on a heavy - textured soil in northern Cochise county; they were the better yielding hybrids from the previous trial. Five new entries, not previously tested in Cochise county, were included. Garst 8345, one of the new entries, was both the top - yielder, at 12,499 pounds per acre, and the hybrid producing the highest adjusted gross income per acre. Hybrids produced by Pioneer, Cargill, DeKalb and NC+ seed companies all yielded more than 12,000 pounds per acre.
    • Comparison of Residual Nitrate and Fertilizer Nitrogen Efficiency in Basin Irrigated Wheat

      Doerge, T.; Knowles, T.; Ottman, M.; Clark, L.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      The relative efficiencies of residual soil NO₃⁻N and fertilizer Nin basin - irrigated wheat production are not well defined. A two-year field study was conducted at the Safford Agricultural Center to investigate what these N efficiencies are under optimum yielding conditions. 'Aldura' durum wheat was grown on the same field site two years in succession. In 1987 a wide range of fertilizer N (0 to 419 lbs /A) applications resulted in residual NO₃⁻N accumulations of 36 to 140 lbs /A in the surface four feet of soil. Residual N plots were split in 1988 with one subplot receiving no additional N while the other was treated with 145 lbs of fertilizer N /A. Grain yield response curves for the –N and +N subplots were used to estimate the marginal rate of substitution (MRS) of soil NO₃⁻N for fertilizer N. The marginal efficiency of residual NO₃⁻N was a constant 16.7 lbs. grain produced /lb. of N across the range of profile N values in this study, while the marginal efficiency of fertilizer N varied from over 17 to below 6 lbs. grain /lb. N. When basin- irrigated wheat is supplied with adequate, but not excessive N, the MRS of soil vs. fertilizer N is about 1:1 although absolute N efficiencies under basin irrigation are considerably lower than those achieved in other grain production systems.
    • Timing Nematicide Application for Control of Stem Nematodes Infecting Arizona Alfalfa

      Nigh, E. L. Jr.; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-09)
      The stem nematode Ditylenchus dipsaci attacks non-dormant Arizona alfalfa in the desert valleys; damage occurs during the cooler months of fall and spring. Efforts to introduce and retain resistant alfalfa has had limited success. From October until temperatures decrease below 50 F., the nematode reproduces and feeds. In warmer years, damage may be sustained from October until spring temperatures exceed 85 F. Chemical control may be warranted during these periods of feeding activity. Field trials were established to determine the efficacy of pesticides registered for use in alfalfa. Temil; Vydate, Furdan, Disyston, Thimet and Dasanit applied either in fall or spring were effective in controlling populations when first detected following dormancy. The best control is obtained when pesticides are applied immediately after harvest and prior to irrigation. Yield increases up to 15-25% were obtained with decreased yields in non -treated controls of 40-80%. Stand decline was reduced as much as 50% when treatments were correctly applied.