• Chemical Freeze Protection of Citrus 1989/1990

      Butler, Marvin; Brown, Paul; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1991-01)
      Three chemical frost protectants were applied to Lisbon lemons using a hand gun operated from a John Bean sprayer. Leaf samples were placed in test tubes with 10 ml of distilled water to determine the temperature at which they froze using a constant temperature bath. Although the sample size was increased by 50 percent over the previous year, the treatments were not significantly different from the untreated.
    • Chill Hour Assessment for the Yuma Area

      Brown, Paul W.; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Citrus Orchard Floor Management 2001-2003: Comparison of a Disk, “Perfecta” Cultivator, and Weed Sensing Sprayer

      Rector, Ryan J.; McCloskey, William B.; Wright, Glenn C.; Sumner, Chris; Wright, Glenn; 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), 2003)
      An optical weed sensing sprayer (WeedSeeker) was evaluated for making postemergence glyphosate herbicide applications in a Yuma, AZ lemon orchard. In addition, mechanical (disk and Perfecta cultivator) and chemical weed control strategies were compared. Results were fairly similar; however, the use of the WeedSeeker units combined with a preemergence herbicide (H1) increased weed control three fold compared to disking (D) and perfecta (P1). Additionally, when the WeedSeeker units were used in conjunction with preemergence herbicides, spray volume was reduced by 66% compared to a conventional sprayer and by 57% when used for postemergence applications only. There was a relationship between weed ground cover and the area sprayed by the WeedSeeker units indicating that maximum postemergence herbicide savings will occur at low weed densities or less than 10% groundcover. The use of a sprayer with an improved suspension system allowed for faster spraying speeds than were possible with the tractor mounted sprayer. Weed control was similar for the conventional and the WeedSeeker sprayer. However, yields were variable for both years. Future investigations will include efforts to develop crop budgets based on experimental operations
    • 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.
    • Citrus Peel Miner Marmara salictella Monitoring Techniques and Control Measures 1996-1997

      Maurer, M. A.; Kerns, D. L.; Tellez, T.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Citrus peel miner populations were monitored to evaluate various methods of trapping citrus peel miners. Observing 25 fruit per tree and 10 trees per block on the lower three feet of the tree canopy provided the best technique for determining the level of citrus peel miner infestations. The use of oleander plants, clear plates and green 3 inch diameter balls sprayed with Tangle-Trap were not effective in trapping citrus peel miner. In 1996, the first of September citrus leaf miner populations rose above the 10% infestation level. Success, Lorsban, Alert and Agri-Mek provided the highest mortality levels of citrus peel miner larvae. In citrus fruit, Success, Lorsban and Alert had the greatest efficacy of citrus peel miner larvae.
    • The Citrus Peel Miner, Marmara salictella, in Arizona Grapefruit in 1994

      Gibson, Roberta; Bacon, Dean; Langston, Dave; Kerns, David; Gibson, Richard; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 1997-11)
      The life history of the citrus peel miner was investigated. The peel miner larvae were found in low levels in grapefruit throughout the summer. In September the infestation level rose to 10%. Peel miners were also found in oleanders, mesquites, grapes and tree cottons. Peel miners were found to infest at higher levels in the skirt of the tree (less than 32. A parasitic wasp of the larval stage was discovered
    • Commercial Evaluation of M-96-015 for Control of Citrus Mealybug, Woolly Whitefly and Citrus Thrips in Lemons

      Kerns, David L.; Tellez, Tony; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      M-96-015 did not appear to effectively control woolly whitefly but does appear to kill citrus mealybug. However, as with other insecticides coverage is a problem. The real benefit of M-96-015 towards citrus mealybug would occur if it prevented their spread. However, we were not able to measure this in this study. As with previous trials, M-96-015 is an effective citrus thrips material.
    • Comparative Control of Phytophthora Root Rot of Citrus with Sodium Tetrathiocarbonate, Metalaxyl, and Dosetyl-Al

      Matheron, M.; Matejka, J.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1991-01)
      This study was initiated to evaluate and compare the effect of root and soil treatments with sodium tetrathiocarbonate (STTC) (Enzone), metalaxyl (Ridomil), and fosetyl-Al (Aliette) on subsequent development of Phytophthora root rot on citrus. Disease development was significantly reduced on rough lemon seedlings treated with STTC or metalaxyl compared to untreated plants when this citrus rootstock was inoculated with sporangia of P. citrophthora or P. parasitica. Growth of rough lemon seedlings in soil naturally infested with P. parasitica that was treated one week before planting with STTC or metalaxyl was equivalent to that obtained in sterilized orchard soil STTC applied as a soil drench at 2,450 ppm was lethal to P. citrophthora and P. parasitica on colonized leaf disks of lepton buried in soil, whereas a similar treatment with metalaxyl at 10 ppm or fosetyl Al at 3,000 ppm did not appreciably affect pathogen viability. Sporangium production on leaf disks of lemon colonized by P. citrophthora and P. parasitica and buried in soil was reduced at least 90% compared to the untreated control six days after treatment of soil with 2,450 ppm of STTC, 10 ppm of metalaxyl, or 3,000 ppm of fosetyl AL These studies demonstrate the potential usefulness of sodium tetrathiocarbonate as a fungicide for control of Phytophthora root rot of citrus. Only fosetyl-Al (Aliette) and metalaxyl (Ridomil) currently are registered for control of Phytophthora diseases on citrus.
    • Consumptive Water Use in High Density Apples

      Moon, John W. Jr.; Slack, Don; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Continued Evaluation of N Fertilization Practices for Surface Irrigated Lemons

      Sanchez, Charles A.; Wright, Glenn C.; Peralta, Manuel; Wright, Glenn; Yuma Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 2003)
      Much of the citrus produced in southwestern Arizona is grown on sandy soils. Because these soils have a low ion exchange capacity, are highly permeable to water, and are prone to nitrate leaching, achieving efficient N management presents a continuing challenge. A field study was conducted on a superstition sand to evaluate the response of lemons to combinations of soil and foliar applied N. Lemon yields significantly increased by soil applied N. Foliar N increased yields of lemons the first harvest at the lower soil N rates. However, there were no other significant responses to foliar N. Overall, there were few meaningful changes in fruit quality to N fertilization. The N content of the leaves increased linearly to soil N application
    • Contributions of Beneficial Soil Fungi to Drought Stress Tolerance of Young Citrus

      Fidelibus, Matthew; Martin, Chris; Stutz, Jean; Wright, Glenn; Department of Botony, Arizona State University (College of Agriculture, University of Arizona (Tucson, AZ), 1997-11)
      Four arbuscular mycorrhizal (AM) fungal isolates (Glomus sp.) from disparate edaphic conditions were screened for effects on whole -plant transpiration of juvenile 'Volkamer' lemon (Citrus volkameriana Ten. and Pasq.) plants of similar shoot mass and canopy leaf area. Mycorrhizal and non -mycorrhizal plants were grown in 8 -liter containers for 2.5 months under well- watered conditions before subjection to three consecutive soil drying episodes of increased severity (soil moisture tensions of -0.02 [still moist], -0.06 [moderately dry], and -0.08[dry] MPa respectively). Whole plant transpiration measurements were made on the last day of each soil drying episode and measurements were repeated on the first and second days after re- watering, when soil profiles were moist. The percent root length colonized by AM fungi differed among isolates. Three AM fungal isolates, Glomus sp. 25A, Glomus mosseae (Nicol. & Gerde.) Gerde. & Trappe 114C, and Glomus intraradices Schenck & Smith FL 208-3 increased root length and subsequently increased lemon plant water use. Conversely, plants inoculated with Glomus mosseae 51C did not enhance lemon plant root length nor improve plant water use compared with nonmycorrhizal control plants. Inoculating citrus with AM fungi that promote root extension may reduce plant water deficit stress under field conditions.
    • Control of Citrus Nematode with Cadusafos

      McClure, Michael A.; Schmitt, Mark E.; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 1996-09)
      Granular (Rugby 10G) and liquid (Rugby 100ME) formulations of Cadusafos were evaluated for the control of Tvlenchulus semipenetrans on mature lemon trees in a commercial citrus orchard at Yuma, Arizona. Three applications of cadusafos, with two months between applications, at the rate of 2 g a.i. /m2 reduced nematode populations to undetectable levels and increased the yield and rate of fruit maturity of 'Rosenberger' lemons. Yields were increased 12,587 kg per hectare with Rugby 100ME and 8,392 kg per hectare with Rugby 10G. Nematode populations were suppressed for at least 12 months after the last application.
    • Control of Ctirus Thrips by Avermectin

      Rethwisch, M. D.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1988-12)
      Two rates of Avermectin were mound- applied; one treatment of Avermectin B one of Carzol were applied by air to citrus in April for control of citrus thrips. Plots were sampled by beating new terminal growth and counting thrips. Ground applications had fewer thrips than applications made by air. Avermectin B1 treatments had significantly fewer thrips than Carzol at all sample dates.
    • Control of Early Woolly Whiteflies Infestations with Foliar Insecticides

      Kerns, David L.; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 2003)
      Five foliar insecticide treatments (Esteem, Provado, Applaud, Assail, and Danitol + Lorsban) were evaluated for their control of early woolly whitefly infestations in lemons. Esteem and Applaud are insect growth regulators that should have little impact on whitefly parasitoids. The impact of Provado and Assail on whitefly parasitoids is not certain, but at high rates may be detrimental, while Danitol + Lorsban will be especially harmful to parasitoids. The impact of these insecticides on woolly whitefly could not be fully determined in this trial due to the effectiveness of parasitoids, Eretmocerus comperei or E. dozieri (exact species not certain), on controlling the whiteflies in this test. However, other research (not reported here) has indicated that all of the insecticide treatments evaluated have good activity against woolly whitefly. Because parasitoids can be extremely effective in mitigating woolly whiteflies populations during the early phases of colonization, it is recommended that chemical control not be utilized until woolly whitefly colonies are common. However, previous experiences suggest that allowing woolly whitefly populations develop extremely high populations should be avoided.
    • Control of Insects and Mites Associated with Citrus in Yuma, Arizona

      Byrne, David N. (College of Agriculture, University of Arizona (Tucson, AZ), 1986-12)
      A variety of insecticides have been tested during the last three years to keep pace with the ever-present demand for effective materials to control mites and thrips on citrus. This need is particularly acute with the recent loss of dicofol (Kelthane), which for years was an industry standard for mite control. Some of the more promising new compounds include Avermectin and NC 21314. Comments are included concerning the registration status of some of the compounds we tested. Cautions are given concerning the development of resistance to compounds which are soon to be available.
    • Control of Jojoba Looper by Insecticides

      Rethwisch, Michael D.; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Control of Phytophthrowa Root and Crown Rot of Apple Trees

      Young, Deborah; Matheron, Michael; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Control of Variegated Grape Leafhoppers by Insecticides

      Rethwisch, Michael D.; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Control of Variegated Leafhopper, Erythroneura variabilis Beamer, By Insecticides

      Rethwisch, Michael D.; Butler, Marvin; Meadows, Mike; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Cultivar and Rootstock Research for the Arizona Citrus Industry

      Wright, G. C.; Wilcox, M.; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 1996-09)
      A lemon rootstock trial and a lemon scion trial were established in 1993. After two years growth, C. volkameriana and C. macrophylla rootstocks have begun to show significant growth and yield increases, compared with 'Swingle' citrumelo and 'Carrizo' citrange. These two rootstocks also have led to larger fruit size, especially early in the season. Trees on Rough lemon rootstock had equivalent growth, but less yield. 'Limoneira 8A Lisbon' scion cultivar had the greatest yield and largest early season fruit size, compared to 'Frost Nucellar', 'Corona Foothills' and `Prior Lisbon' lemons.