• Rejuvenation of mature pecan trees by pruning

      Kilby, Michael; Gibson, Richard; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      Neglected mature 'Wichita' pecan trees were rejuvenated using various pruning techniques in 1997. Trees were pruned using proven horticultural techniques which included dehorning (cutting main scaffolds to within 2 feet of trunk) and cutting main scaffolds by 50%. To date the treatments have resulted in an increase in yield when compared to trees that received no pruning. In 1999 the grower has developed an orchard management program conducive to maximum production.
    • Rejuvenation of Neglected, Mature "Wichita" Pecan Trees By Corrective Pruning

      Gibson, Richard; Kilby, Michael; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2002-02)
      An attempt was made in 1997 to rejuvenate neglected, mature 'Wichita' pecan trees in a commercial Pinal County grove by applying two types of heading back pruning cuts. The treatments were applied during the dormant season prior to the growing season. The trees were pruned using proven horticultural techniques which included dehorning (cutting main scaffolds to within 2 feet of the trunk) and cutting main scaffolds by 50%. After four years of data, the trees receiving no pruning treatments are producing as well or better than trees to which the pruning treatments were applied. The data suggests that a return to normal irrigation and fertilization practices alone will return neglected, water-stressed trees to normal productivity as early as trees that have been headed-back.
    • Relationship of Viroids to Macrophylla Decline

      Taylor, Kathryn; Langham, Richard; Xiong, Zhongguo; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 1996-09)
      A physiological characterization has established that vascular changes in Macrophylla decline affected trees are not similar in character to xyloporosis affected trees. In addition, a survey of Macrophylla decline affected citrus did not establish any genetic similarity between Macrophylla decline and xyloporosis. We report diagnosis of either CCV or CEV by reverse transcription-polymerase chain reaction (RT-PCR), as well as diagnosis of Macrophylla decline or xyloporosis by Zn-distribution, water conductivity, accumulation of decline- specific proteins and examination of phloem morphology in lemon trees on the Macrophylla rootstock.
    • Relative Susceptibility of Citrus Thrips Nymphs and Adults to Insecticides

      Kerns, David L.; Wright, Glenn; Gibson, Rick (College of Agriculture, University of Arizona (Tucson, AZ), 2002-11)
      Agri-Mek, Assail, Baythroid, Carzol, and Success were all evaluated for their activity towards citrus thrips nymphs relative to adults. Based on leaf dip bioassays, Dimethoate was approximately 3 times more toxic to the adults than to the nymphs. However with leaf dip bioassays, a 3-fold difference, although statistically significant, is usually inconsequential. Success was the only insecticide that demonstrated a noteworthy difference in toxicity to nymphs compared to adults in the bioassay; it was 45 times more toxic to the nymphs than to the adults. Based on X2 contingency tables, lemon trees treated with Carzol, Success, or Baythroid all had significantly lower percentages of nymphs relative to the untreated control. Based on these data, when the citrus thrips population is composed primarily of nymphs, citrus growers and pest control advisors might consider using Carzol, Success, or Baythroid since they appear to impact the nymph population more than the adult population.
    • Report on the Salt River Valley Citrus Experiment Station

      True, Lowell; Bacon, Dean; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1991-01)
    • Residual activity of insecticides to citrus thrips on lemon foliage

      Kerns, David L.; Tellez, Tony; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      The residual activity of insecticides to second instar citrus thrips was measured on lemon foliage in 1998. In April, Dimethoate and Agri-Mek provided only knockdown control of thrips, dropping to <70% mortality by 3 days after treatment (DAT). Baythroid performed slightly better, providing 95% mortality 3 DAT, but by 7 DAT was giving about 74% mortality. Alert, Carzol, Success and AZEXP-2 provided the longest residual activity, lasting 7 days, but began to slip at 14 DAT. AZEXP-1 induced only 74% 0 DAT. Although, residual activity in general was greater in June than April, however this increase in residual activity did not necessarily increase the length of commercially acceptable residual. Agri-Mek and Dimethoate still only provided knockdown activity, and Baythroid was still giving 3 days of good activity. AZEXP-1 performed much better following the June application relative to the April application, providing 3 days of adequate activity. Although we are not certain the reason for this result, it maybe due to the adsorption properties of this chemical relative to leaf physiology. Alert performed similarly in June and April, and Carzol, Success and AZEXP-2 each lasted about 1 week longer.
    • Residual Activity of Insecticides to Citrus Thrips on Lemon Foliage

      Kerns, David L.; Tellez, Tony; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      The residual activity of insecticides to second instar citrus thrips was measured on lemon foliage in 1998 and 1999. Dimethoate, Agri-Mek and acetamiprid provided only knockdown control of thrips, dropping to <70% mortality by 3 days after treatment (DAT). Baythroid performed slightly better, providing about 95% mortality 3 DAT during three of the evaluation periods, but by 7 DAT was giving about 75% mortality. Alert, Carzol, and Success provided the longest residual activity, lasting 7 to 14 DAT. Residual activity in general appeared to be greater in the May and June evaluation, relative to the April evaluation. The apparent shorter residual activity under cooler condition in April 1998 is not understood but maybe due to a difference in the physiological nature of the leaves earlier in the season.
    • Response of Grape Cultivars to Nitrogen and Phosphorus

      Stroehlein, J. L.; Janat, M. M.; McGuide, C. E.; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
      The response of 11 different varieties of grapes treated with different levels of N was studied over a seven-year period Phosphorau fertilizer was applied midway through the study. Tissue samples were tested for total P and NO₃-N content, and yield determined annually. The results showed a positive interaction in tens of increased yield between N and P when sufficient quantities of both nutrients were provided
    • Response of Lemon to Micronutrient Fertilization

      Sanchez, Charles A.; Wright, Glenn; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 2004)
      A study was initiated in the spring of 2003 to evaluate the response of lemons to soil and foliar applied micronutrients for two growing season (2003-2005). Soil applied Fe, Zn, Mn, and Cu was applied in sulfate form and B as Solubor in shallow holes around the skirt of each tree. Foliar applied micronutrients were all applied as “Metalosate” products. Lemon leaf tissue analyses show marginal levels of Zn, Mn, and Cu throughout the study. In 2003-2004, soil fertilization sometimes increased leaf nutrient composition but there was no effect to foliar fertilization. In 2004-2005, ,leaf B and Zn increased to soil fertilization and leaf Mn and Cu increased to foliar fertilization Overall, there were no significant differences in yield or quality to micronutrient fertilization in either growing season.
    • Response of Micro-Sprinkler Irrigated ‘Lisbon’ lemons to N Rate and Source on a Superstition Sand

      Sanchez, C. A.; Peralta, M.; Wright, Glenn (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. Studies were conducted during 1999, 2000, and 2001 to evaluate the response of micro-sprinkler irrigated lemons to N rate (0, 1.8, and 3.6 kg N tree-1 yr-1) and N source (UN32, CAN-17, CN9, and mixed program) on Superstition Sand. Lemon yield increased by N rate during the first and second harvests in 1999, 2000, and 2001. In 1999, yields increased linearly to 3.6 kg N tree-1 yr-1 but in 2000 and 2001 yields were maximized at 1.8 kg N tree-1 yr-1. In 1999 where larger increments of N were applied over a smaller time period relative to the other seasons, UN32 seemed to decrease yields at the highest N rate. There were no significant effects to N source in 2000 and 2001.
    • The Response of Table Grape Growth, Production, and Ripening to Water Stress

      Garrot, D. J. Jr.; Kilby, M. W.; Gibson, R. D.; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • The Response of Table Grape Growth, Production, and Ripening to Water Stress

      Garrot, D. J.; Gibson, R. D. Jr.; Kilby, M. W.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Four year old 'Flame Seedless' grapevines, located in a commercial vineyard, were subjected to increased water stress levels based on infrared canopy temperatures and the Crop Water Stress Index (CWSI) for two years. CWSI levels were approximately .18, .30 and .33 for the wet, medium and dry treatments. In the first year there were no significant differences in yield however, there was a significant reduction in the amount of water applied in both the medium and dry treatments when compared to the wet treatment. In addition, the wet treatment had significantly greater growth during the first growing season when comparing pruning weights.
    • Results of 'Fallglo' Trials for Citrus in Arizona - 2001

      Wright, Glenn C.; Peña, Marco; Wright, Glenn; Gibson, Rick; Department of Plant Sciences, U. of A., Yuma Mesa Agriculture Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-11)
      A 'Fallglo' mandarin trial was established at the Yuma Mesa Agriculture Center in 1995. Results suggest that trees on C. volkameriana rootstock, rough lemon rootstock, and, in 2001-02, Gou Tou orange rootstock had the greatest yields. There was little effect of rootstock upon fruit size or juice quality.
    • Results of New Cultivar Selection Trials for Lemon in Arizona - 2001

      Wright, Glenn C.; Peña, Marco; Wright, Glenn; Gibson, Rick; Department of Plant Sciences, U. of A., Yuma Mesa Agriculture Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-11)
      Three lemon cultivar selection trials are being conducted at the Yuma Mesa Agriculture Center in Somerton, AZ. Data from these trials suggest that 'Cavers Lisbon' and 'Limonero Fino 49' selections may be suitable alternatives for the varieties most commonly planted in Southwest Arizona today.
    • Results of New Cultivar Selection Trials for Lemon in Arizona - 2002

      Wright, Glenn C.; Peña, Marco A.; Wright, Glenn; Department of Plant Sciences, U. of A.; Yuma Mesa Agriculture Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2003)
      Three lemon cultivar selection trials are being conducted at the Yuma Mesa Agriculture Center in Somerton, AZ. Data from these trials suggest that ‘Limonero Fino 49’ selections may be a suitable alternative for the varieties most commonly planted in Southwest Arizona today. ‘Cavers Lisbon’ and ‘Villafranca’ might also be planted on an experimental basis
    • Results of New Cultivar Selection Trials for Lemon in Arizona - 2006-07

      Wright, Glenn C.; Wright, Glenn; Department of Plant Sciences, U. of A., Yuma Mesa Agriculture Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2007-10)
      Three lemon cultivar selection trials are being conducted at the Yuma Mesa Agriculture Center in Somerton, AZ. Data from these trials suggest that 'Limonero Fino 49' and 'Cascade Eureka' selections may be a suitable alternative for the varieties most commonly planted in Southwest Arizona today. 'Femminello' and 'Villafranca' might also be planted on an experimental basis
    • Results of New Cultivar Selection Trials for Lemon in Arizona – 2004-05

      Wright, Glenn C.; Wright, Glenn; Department of Plant Sciences, University of Arizona; Yuma Mesa Agriculture Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2004)
      Three lemon cultivar selection trials are being conducted at the Yuma Mesa Agriculture Center in Somerton, AZ. Data from these trials suggest that ‘Limonero Fino 49’ selections may be a suitable alternative for the varieties most commonly planted in Southwest Arizona today. ‘Femminello’ and ‘Villafranca’ might also be planted on an experimental basis.
    • Results of New Cultivar Selection Trials for Lemon in Arizona – 2005-06

      Wright, Glenn C.; Wright, Glenn; Department of Plant Sciences, University of Arizona; Yuma Mesa Agriculture Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2005)
      Three lemon cultivar selection trials are being conducted at the Yuma Mesa Agriculture Center in Somerton, AZ. Data from these trials suggest that ‘Limonero Fino 49’ selections may be a suitable alternative for the varieties most commonly planted in Southwest Arizona today. ‘Femminello’ and ‘Villafranca’ might also be planted on an experimental basis.
    • Results of New Cultivar Selection Trials for Orange in Arizona - 2001

      Wright, Glenn C.; Peña, Marco; Wright, Glenn; Gibson, Rick; Department of Plant Sciences, U. of A., Yuma Mesa Agriculture Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-11)
      Three orange cultivar trials have been established in Arizona, one at the Yuma Mesa Agricultural Center, Yuma, AZ and one at the Citrus Agriculture Center, Waddell, AZ. For the navel orange trial in Yuma, 'Fisher' navel continues to have the greatest yield, but is unacceptably granulated. For the 'Valencia' trial in Yuma, none of the cultivar/rootstock combinations have been particularly successful. For the Waddell trial, only the first year data has been collected.
    • Results of New Cultivar Selection Trials for Orange in Arizona - 2003

      Wright, Glenn C.; Peña, Marco A.; Wright, Glenn; Department of Plant Sciences, U. of A.; Yuma Mesa Agriculture Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2003)
      Three orange cultivar trials have been established in Arizona, one at the Yuma Mesa Agricultural Center, Yuma, AZ and one at the Citrus Agriculture Center, Waddell, AZ. For the navel orange trial in Yuma, ‘Fisher’ navel continues to have the greatest yield, but is unacceptably granulated For the Waddell trial, the second year data has been collected, and suggests that ‘Fisher’ and ‘Beck- Earli’ are outperforming the other cultivars tested to date.