• California Red Scale Again Eradicated from Yuma County

      McDonald, H. H.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1991-01)
      Since 1973, Yuma County has had three apparently unrelated infestations of California Red Scale (CRS). The Yuma County citrus Pest Control District (YCCPCD) was successful in eradicating the first two in 1980 and 1984, respectively. We are continuing our spray program on the third, but our detection methods indicate that this infestation has now also been eradicated.
    • California Red Scale Eradicated in Yuma County Again

      McDonald, Herbert H. (College of Agriculture, University of Arizona (Tucson, AZ), 1986-12)
      For the second time in two decades, the Yuma County Citrus Pest Control District has been successful in eradicating an infestation of California Red Scale in a commercial citrus grove within its boundaries. The first infestation, found in 1973, was declared eradicated in 1980. The latest infestation was found in 1984 and will be eradicated in record time. Eradication can be declared early next year after the third series of three sprayings each.
    • Characterization of Alternaria isolates associated with Alternaria Rot of Citrus

      Pryor, Barry; Matheron, Mike; Figuli, Patricia; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 2003)
      Alternaria rot of citrus is a serious problem in citrus production world wide. In Arizona, the disease is most commonly found in Minneola tangelos and navel oranges grown in Maricopa County. Alternaria rot occurs primarily as a stem-end rot on fruit held in cold storage. However, under optimum conditions the disease occurs as a stylar-end rot in the orchards. In Arizona, the disease can significantly reduce yield, and annual fruit losses have been estimated at 0.5 box per tree. In terms of fruit quality, this disease can be a serious problem for the fresh fruit market as well as for the processing industry because only a small amount of rot imparts a bitter flavor and small black fragments of rotted tissue spoil the appearance of the juice. The application of fungicides is the most common tactic used to reduce losses to this disease. However, to date, no consistent reduction in disease has been achieved through chemical applications. This suggests that additional information relating to the biology of the pathogen and the epidemiology of disease will be necessary for the successful development of a reliable disease management program.
    • Chemical Control and Integrated Pest Management of Woolly Whitefly

      Kerns, David L.; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 2004)
      Five foliar insecticide treatments (Esteem, two rates of Provado, two rates of Applaud, Prev-am, and Danitol + Lorsban) were evaluated for their control of woolly whitefly infestations in grapefruit. All of these products demonstrated efficacy in mitigating woolly whitefly populations. Danitol + Lorsban was the best knock-down treatment evaluated, but for sustained control, Esteem appeared to be most effective. Applaud demonstrated good activity, but the rate we tested may be a little low; the 1.0 lb/ac rate should be evaluated. Provado at 19 oz/ac was a good treatment, while the 10 oz/ac rate appears to be sub-par. Prev-am is a oil based contact material and demonstrated good initial activity. Soil injections of 16 and 32 oz/ac of Admire were very effective against WWF, and there were no detectable differences between the two rates. Previous experiments with soil injections of Admire in citrus suggested that as much as six weeks needs to pass before the trees have enough time to adequately take up the Admire from the soil. However, these data suggest that smaller trees, about 10 ft tall, may require as little as two weeks to pick up the material.
    • Chemical Control and Integrated Pest Management of Woolly Whitefly

      Kerns, David L.; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 2007-10)
      Eight foliar insecticide treatment regimes (single applications of Esteem, Danitol + Lorsban, Applaud, Provado and Prev-am, and two applications of Applaud, Provado, and Prev-Am) were evaluated for management of woolly whitefly infestations in grapefruit. All of these products demonstrated efficacy in mitigating woolly whitefly populations. Danitol + Lorsban appeared to be the best knock-down treatment evaluated, but Provado and Prev-Am also demonstrated good activity. For sustained control, all of the treatments were effective; however, Prev-Am required an additional application to achieve equivalent control. Soil injections of 16 and 32 fl-oz/ac of Admire were very effective against WWF, and there were no detectable differences between the two rates. The Admire appeared to require about 27 days after injection to demonstrate consistent activity.
    • Chemical Control of Citrus Thrips on Lemons in the Low Desert Areas of Arizona

      Kerns, David L.; Maurer, Michael; Langston, Dave; Tellez, Tony; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 1997-11)
      Insecticides were evaluated for their efficacy to citrus mealybugs on lemons at three spray gallonages, 60, 240, and 600 gallons per acre. None of the products tested exhibited any activity at 60 or 240 gallons per acre. At 600 gallons per acre, Lorsban at 6 qt/A + NR-415 oil at 1.4% v/v, Supracide at 2 pt /100 gal + Kinetic at 0.25% v/v, and Applaud at 2.0 lbs -ai/A + NR -415 oil at 1.4% v/v all demonstrated the best activity. Provado at 0.1 lbs-ai/A + NR-415 oil at 1.4 %, Danitol at 0.4 lbs-ai/A + Lorsban at 4 qt/A + NR-415 oil at 1.4% v/v, and Nexter at 0.3 lbs-ai/A + NR-415 oil at 1.4% v/v showed good activity. Weaker treatments included Agri-Mek at 10 and 20 oz/A, Knack and Difenolan. For maximum control, growers should treat before the fruit is heavily infested, and use high gallonages of spray solution at a high pressure, the spray must penetrate the waxy coating to achieve activity. If applicable, a spray oil should be included to help break up the wax. However, if Supracide is used, use a high rate without oil.
    • Chemical Freeze Protection of Citrus 1987/1988

      Butler, M.; Brown, P.; Fallahi, E.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1988-12)
      Research has shown that the presence of ice-nucleation-active (INA) bacteria, such as Pseudomonas syringae and Erwinia herbicola, will result in ice formation several degrees centigrade higher than would otherwise occur. Seven possible chemical frost protectants were applied to Lisbon lemons of the Yuma Mesa Ag Center. Four replications of effectiveness of the materials were evaluated by determining tip bum and fruit damage following two subfreezing episodes in December 1987. There were no statistically significant differences between treatments under the conditions of this study.
    • Chemical Freeze Protection of Citrus 1988/1989

      Butler, Marvin; Brown, Paul; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1991-01)
      Five chemical frost protectants and a water treatment were applied to Lisbon lemons by dipping branches to insure complete coverage. A constant temperature bath was used to determine the effect of chemical frost protectants on the freezing temperature for leaf samples placed in test tubes with 10 ml of distilled water. Although the relative temperature at which the different treatments froze remained fairly constant, the differences were not significant.
    • 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.