• Evaluation of Fungicidal Management of Alternaria Rot on Citrus Fruit in 2000-2001 Season

      Matheron, Michael E.; Porchas, Martin; Wright, Glenn; Kilby, Mike; University of Arizona, Yuma Agricultural Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-02)
      Alternaria fruit rot on Minneola tangelos and navel oranges can reach economically important levels in central Arizona. The objective of this study was to test the efficacy of a new fungicide in development, BAS 500, for disease management. A trial was conducted in a commercial Minneola tangelo grove with a history of Alternaria fruit rot. Within this grove, nine trees were sprayed monthly from August to December 2000 with BAS 500 at a rate of 0.25 lb active ingredient per acre. Another nine trees were not sprayed and served as controls. Disease severity was evaluated monthly from September 2000 to March 2001 by counting the number of infected fruit that had dropped from trees. No disease was evident on fruit from August through November, when fruit were green. By December the fruit had matured and turned color; additionally, the first fruit were detected with Alternaria fruit rot. In December and January there was little difference in the number of infected fruit on treated compared to nontreated trees. On the other hand, by February and March the cumulative number of infected fruit from trees treated with BAS 500 was 3.0 and 3.7 %, respectively, whereas the cumulative number of diseased fruit from nontreated trees during the same months was greater at 4.9 and 6.4 %, respectively. This study will be repeated next year with an adjusted spray schedule with the goal of increasing the level of disease control.
    • Evaluation of Insecticide Applications for Citrus Thrips Control Under Hot Conditions

      Kerns, David L.; Tellez, Tony; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2002-02)
      A small plot efficacy trial was conducted evaluating citrus thrips control under hot conditions. Average daily maximum temperatures ranged from the mid-90’s to low 100°F’s. Success and Carzol were the most efficacious products evaluated, followed by Lorsban and Dimethoate. Both Lorsban and Dimethoate provided good initial thrips control but were short lived. Lorsban appeared to have a slightly longer residual than Dimethoate. Both of the pyrethroids, Baythroid and Danitol, performed poorly. Neither provided good thrips knockdown or residual control. Pyrethroids should be avoided for thrips control when temperatures equal or exceed 95°F. We were not able to demonstrate any adverse effect on efficacy towards thrips by acidifying Success. However, Success is not prone to hydrolysis at high pHs, and acidification is not necessary or advised.
    • Evaluation of Milestone Herbicide for Early Post-emergence Weed Control in Citrus on the Yuma Mesa

      Kerns, David L.; Tellez, Tony; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      When applied early-postemergence, Milestone at 0.75 and 1.0 lbs-ai/A provided excellent control of summer annual grasses and broadleaf weed for as long as 4 months, equivalent to Karmex. Princep and Krovar also provided good weed control but appeared to offer slightly shorter residual against some broadleaf species. Solicam, although it provided good weed control, particularly of the grasses, was the weakest material evaluated in this trial. Although Karmex is notorious for causing crop injury on the sandy soils of the Yuma Mesa, we did not detect any injury from this herbicide or any others in this trial.
    • Evaluation of Pre-Petal Fall Citrus Thrips Control

      Kerns, David L.; Tellez, Tony; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2002-02)
      A small plot trial was conducted to evaluate the benefit of applying insecticides for citrus thrips management pre-petal fall. Because of low thrips densities during the pre-petal period, we were not able to discern tangible benefits from making prepetal applications. However, in situations where fruit is present and petal fall has not fully occurred, these applications may be useful to protect these fruit. Of the acute toxicants evaluated pre-petal fall (Assail and Success), Assail appeared to be the best choice. However, if temperatures are approaching 95°F, Assail should be avoided. Pre-petal fall applications of Surround and Snow are beneficial in respect that several applications of these products may be required to obtain adequate coverage, and by making these applications during the pre-petal fall period, thrips can be managed before many susceptible fruit are present.
    • Evaluation of Temik (aldicarb) for the Control of the Pecan Aphid Complex for Pecans Grown in Arizona

      Kilby, Michael W.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      This experiment was conducted to extend the label for Temik use in Arizona pecan orchards for aphid control. Spring application of Temik controlled both yellow and black aphids throughout the season and significantly increased yield.
    • Evaluation of thinning agents for "kinnow" mandarins

      Maurer, Michael A.; Taylor, Kathryn C.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      An experiment was designed to determine the effectiveness of foliar prebloom boron (B) sprays for thinning 'Kinnow' mandarins (Citrus reticulata). Treatments consisted of a control and foliar B applied at 1000, 1500, 2000, 2500 and 3000 ppm. Leaf tissue B levels were not significant between treatments. Likewise, fruit quality was similar for all treatments. Fruit weight and number were significantly greater for the control compared to the 1500, 2000, 2500 and 3000 ppm B treatments for the undersize fruit. There was a clear reduction in yield as the rate of B applied increased, however, the reduction was not statistically significant.
    • Foliar Applications of Boron to Pecan Trees Does Not Affect Fruit Set

      Kilby, Michael W.; Call, Robert; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Boron was applied as a foliar spray to pecan trees in a pecan orchard located in Cochise County. Single or repeated application prior to pollination did not affect nutlet set. Leaf analysis indicated that the boron levels in all trees were in the sufficient range for optimum growth and production.
    • Foliar applications of Lo-Biuret Urea and Potassium Phosphite to Navel Orange Trees

      Wright, Glenn; Walworth, James; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2002-02)
      This experiment was established in January 2000 in a block of 'Washington' navel orange trees at Verde Growers, Stanfield, AZ. Treatments included: normal grower practice, winter low biuret (LB) urea application, summer LB urea application, winter LB urea application plus winter and spring potassium phosphite, winter LB urea application plus summer potassium phosphite, and normal grower practice plus spring potassium phosphite. Each treatment was applied to approximately four acres of trees. For 2000-01, yields ranged from 40 to 45 lbs. per tree, and there was no effect of treatments upon total yield. There was a slight effect upon fruit size and grade. Trees subject to summer LB urea application had significantly more fruit of size 56, compared to trees subject to winter LB urea, and untreated, and untreated trees had significantly more fruit of size 88 than did treated trees. Also, treated trees had slightly more fruit in the fancy grade than did untreated trees.
    • Fungicidal Performance in Managing Septoria Leaf Spot of Pistachio in Arizona

      Call, Robert E.; Matheron, Michael E.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Septoria leaf spot was detected in the United States for the first time in 1964 within an experimental pistachio planting at Brownwood, Texas. The first observation of the same disease in Arizona pistachio trees did not occur until 1986. In 1988, a survey of the 2,000 acres of pistachio orchards in southeastern Arizona revealed a widespread incidence of the disease. Since the initial discovery of the disease, Septoria leaf spot has appeared annually in some Arizona pistachio acreage. The onset and severity of the disease is influenced by summer rainfall that occurs in this region. Pistachio trees infected with Septoria leaf spot and not treated with an effective fungicide can defoliate in the autumn up to 2 months prematurely. The objective of this field study was to evaluate the efficacy of several different fungicides against this disease. All fungicides were applied to tree foliage on July 13 and August 10, 1999. Disease severity was lowest on trees treated with Flint (trifloxystrobin). Other materials that significantly reduced the final level of disease compared to nontreated trees included Abound (azoxystrobin), Break (propiconazole), and Procop R (copper hydroxide).
    • Girdling "Fairchild" Mandarins and "Lisbon" Lemons to Improve Fruit Size

      Wright, Glenn C.; Wright, Glenn; Kilby, Mike; Yuma Mesa Agriculture Center, University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      'Fairchild' mandarins in the Phoenix area and 'Lisbon' lemons in Yuma were girdled beginning in November 1996. November, March and May girdling of the mandarins led to the greatest yield the first year, while March and May girdling led to the greatest yield in years 2 and 3. March girdling yield increases were generally due to greater fruit numbers, while in May, yield increases were due to greater fruit numbers and fruit size. Returns per acre suggest that March and or May girdling of mandarins will lead to greater profits for the grower. Like mandarins, lemon yields were greater following November, or November and March girdling after one year of the experiment. However, yields of these trees dropped considerably the second year, and the trees appear to be in an alternate bearing cycle. No lemon girdling treatment appears to be better than the untreated trees after three years.
    • Growing Blackberries in the Low Desert

      Wright, Glenn C.; Wright, Glenn; Kilby, Mike; Department of Plant Sciences, Yuma Mesa Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Twenty-five plants of each of ten blackberry cultivars from Arkansas and Texas were established at the Yuma Mesa Agriculture Center in spring 1994. All the Arkansas cultivars died. Of the Texas cultivars, 'Rosborough' and 'Womack' performed the best, followed by 'Grison' and 'Brazos'. Important cultural practices, harvesting practices and potential marketing strategies are discussed
    • Growth of Citrus volkameriana inoculated with AM fungi in moist or periodically dry soils

      Fidelibus, Matthew W.; Martin, Chris A.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      ‘Volkamer’ lemon (Citrus volkameriana Tan. and Pasq.) seedlings were inoculated with either of five communities of arbuscular mycorrhizal (AM) fungi collected from either citrus orchards in Mesa and Yuma, Arizona or from undisturbed Sonoran or Chihuahuan desert soils. Plants were then grown for four months under low or high irrigation frequency treatments such that soil water tension reached about -0.01 MPa (moist) or -0.06 MPa (periodically dry), respectively. Plants grown in moist substrate had greater shoot mass than plants grown in periodically dry substrate. Plants inoculated with AM fungi from the Yuma orchard soil had significantly less shoot and root mass, higher specific soil respiration rates, and lower photosynthesis rates than plants treated with inoculum from other soils. Plant phosphorus nutrition did not limit growth. These data show that growth of ‘Volkamer’ lemon seedlings can be substantially affected by arbuscular mycorrhizal fungal communities in moist or periodically dry soils.
    • Hydrogen Cyanamide Trial on Table Grapes, 1985/1986

      Butler, Marvin; Kilby, Mike; Rush, Bob; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Hydrogen Cyanamide Trial, 1984/1985

      Butler, Marvin; Kilby, Mike; Rush, Bob; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Impact of preplant soil treatments on survival of Phythophthora in citrus soils

      Matheron, Michael; Porchas, Martin; Maurer, Michael; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      Several different approaches are used with respect to land preparation prior to replanting citrus in Arizona. A study was initiated to examine the effect of cultural preplant practices on the survival of Phytophthora in citrus orchard soils. In June, 1998, a 2-gallon volume of soil was collected from eight different sites within a mature lemon planting on a sandy soil in Yuma or a lemon planting on a heavier soil in Mesa, AZ. Each initial sample was pre-tested, found to contain Phytophthora parasitica, then thoroughly mixed and distributed into six 1-qt plastic containers, which were subjected to different environmental and cultural conditions. The soil in each container was tested for the presence of P. parasitica 1, 4 and 9 months after initiation of the study. The preliminary results of this ongoing study are as follows. Detection of P. parasitica was lower in non-irrigated as compared to irrigated soil. P. parasitica was not detected in non-irrigated soil subjected to a mean temperature of 38°C (100° F) for 3 months. During the 9-month period of time, detection of P. parasitica in soil planted to alfalfa was not reduced compared to soil planted to citrus. Of the treatments examined, dry summer fallow may be the most effective method of reducing the population of P. parasitica to below detectable levels; however, these preliminary findings must be validated by additional planned tests.
    • Improving Management and Control of Fungal Diseases Affecting Arizona Citrus Trees, 1997

      Matheron, Michael; Maurer, Michael; Porchas, Martin; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Studies were conducted to evaluate potential chemical disease management tools for Alternaria fruit rot on navel oranges and Coniophora brown wood rot on lemon trees, to investigate the possible effect of branch diameter on development of Coniophora wood rot on lemon trees and to summarize our evaluations of citrus rootstocks with respect to relative resistance to root rot and stem canker development when challenged with Phytophthora citrophthora and P. parasitica. We were unable to reduce the level of Alternaria fruit rot on navel oranges with single applications of Abound or copper hydroxide following significant rainfall events. Wood decay in lemon branches inoculated with Coniophora eremophila was significantly suppressed by Abound and a thick formulation of sodium tetrathiocarbonate. The degree of Coniophora brown wood rot in lemon branches of different diameters was variable, although the level of disease in 10 mm diameter branches was significantly smaller than the amount of wood decay in 30 mm diameter branches. Root loss due to Phytophthora citrophthora and P. parasitica in Citrus macrophylla, rough lemon, C. volkameriana and Troyer citrange was lower than most of the 36 different rootstocks tested. On the other hand, root loss on Carrizo citrange, C-35 citrange and sour orange was among the higher values of disease recorded. Stem canker development due to both species of Phytophthora on Troyer citrange, Carrizo citrange, sour orange and Citrus macrophylla was lower than most of the 36 rootstocks tested. Stem cankers on rough lemon and Citrus volkameriana were among the higher values of disease recorded.
    • Influence of Nut Cluster Position on the Incidence of Viviparity for the Pecan Cultivars "Western Schley" and "Wichita"

      Gibson, Richard; Kilby, Michael; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Vivaparity, a significant quality- reducing condition found in pecans grown in warm, temperate climates, was evaluated by location of the pecan nut within the cluster in two varieties, "Wichita " and "Western Schley". Percentage vivaparity was not affected by position.
    • Insecticidal and Yield Enhancement Qualities of Surround Particle Film Technology in Citrus

      Kerns, David L.; Wright, Glenn C.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2002-02)
      Surround WP was evaluated at various spray volumes to determine if volumes lower than the label recommended volume of 250 gallon per acre would provide equivalent citrus thrips control and yield enhancement potential. All the spray volumes evaluated (50, 100, 150, and 250 gpa) appeared to be equally effective. It appears that as long as the spray coverage appears to be visually adequate, then coverage is sufficient. Application of Surround WP led to some increase in fruit size, particularly for the first harvest.
    • Insecticide Rotation and Pre-Petal Fall Applications for Citrus Thrips Management

      Kerns, David L.; Tellez, Tony; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Under low citrus thrips pressure and cool temperatures, Alert, Baythroid, Carzol, Success and Acetamiprid applied at petal fall were all effective control agents. Mid-season applications of Baythroid and Danitol were also effective but appeared to be slightly inferior to Success and Alert in residual control. Despite the prolonged blooming and petal drop period experienced during this trial, plots receiving pre-petal fall applications of Acetamiprid did not produce higher quality fruit than treatments where applications began following petal fall. The fact that thrips densities were low during this period may be the reason. Before pre-petal fall insecticide applications can be deemed useful and economically justifiable, evaluations must be made at higher thrips infestation levels.
    • International Society of Citrus Nurserymen Conference Report

      Wright, Glenn C.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      This report summarizes some of the information that I gained during a trip to the Mediterranean region during Spring 1997. The first two days of the trip were spent in Murcia, Spain, as a guest of Dr. Angel Garda Lidón. We discussed the Spanish lemon industry. After Murcia, I traveled to Valencia, Spain to take part in an International Society of Citrus Nurserymen pre-conference tour. The conference itself took place in Montpellier, France. Following the conference, I participated in a post-conference tour to Sicily.