• Citrus Orchard Floor Management 2001: Comparison of a Disk, "Perfecta" Cultivator, and Weed Sensing Sprayer

      McCloskey, William B.; Wright, Glenn C.; Sumner, Christopher P.; Wright, Glenn; Gibson, Rick; Department of Plant Sciences, University of Arizona, Tucson, Arizona; Department of Plant Sciences, Yuma Mesa Agricultural Center, University of Arizona, Yuma, Arizona; Yuma County Pest Abatement District, Yuma, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 2002-11)
      Mechanical (disk and Perfecta cultivator) and chemical weed control strategies were compared in a Yuma, AZ lemon orchard. In addition, an optical weed sensing sprayer (WeedSeeker) was evaluated for making post-emergence Roundup Ultramax herbicide applications. The use of pre-emergence herbicides in conjunction with the WeedSeeker spray units has the potential to significantly reduce the amount of post-emergence herbicide and water needed to spray flood irrigated citrus orchards. There was a relationship between weed ground cover and the area sprayed by the WeedSeeker units that indicated the maximum herbicide saving will occur a low weed densities. The use of the Kawasaki Mule with its superior suspension system allowed for faster spraying speeds than were possible with the tractor mounted sprayer and this also reduced spray volume per plot. Weed control was similar for the conventional and the WeedSeeker sprayers. Future investigations will include efforts to improve the estimation of percent weed groundcover, the use of higher rates of pre-emergence herbicides and the development of crop budgets based on experimental operations.
    • Effect of Foliar Boron Sprays on Yield and Fruit Quality of Navel Oranges in 1998 and 1999

      Maurer, Michael; Truman, James; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      A field study was designed to determine if foliar boron (B) sprays could increase fruit set and yield of 'Parent Washington' navel oranges (Citrus sinensis). Treatments consisted of two application timings (prebloom and postbloom) and five application rates 0, 250, 500, 750 and 1000 ppm B as Solubor. Leaf B levels had a significant response to both application timing and rate in 1998, but there were no significant differences in 1999. There were no significant difference in fruit quality or yield in either year.