• Arizona Cooperative Citrus Registration-Certification Program Celebrates Silver Anniversary

      McDonald, H. H.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1991-01)
      New methods of determining the content of virus and virus-like disorders in citrus trees are heralding a new era of the Arizona Cooperative Citrus Registration-Certification Program (ACCRCP). It has been 25 years since the first budwood was released to participating nurseries. During that time, the program has relied on indexing using various indicator plants. Last year, indexing was begun in the laboratory using the ELISA unit for tristeza tests. Efforts are now being made to obtain antiserum for stubborn disease which currently has no reliable indexing method using indicator plants.
    • The Ash Whitefly as a Pest of Citrus

      Byrne, David N.; Butler, Marvin; Department of Entomology (College of Agriculture, University of Arizona (Tucson, AZ), 1991-01)
    • 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.
    • 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.
    • 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.
    • 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 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)
    • Distribution of Two Species of Phytophthora Within the Citrus Acreage in Arizona

      Matheron, M.; Matejka, J.; Bacon, D.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1988-12)
      Pkvtophthora citrophthora and P. parasitica cause gummosis and root rot of citrus trees in Arizona. A disease survey was initiated to determine the relative distribution of each pathogen within the citrus acreage of Maricopa and Yuma Counties. Both pathogens were recovered at the same time from 75% and 17% of orchards containing Phytophthora in Maricopa and Yuma County, respectively. P. citrophthora alone was found in 15% of the groves containing Phytophthora in Yuma County, while P. parasitica alone was detected in 25% and 68% of the citrus plantings containing Phytophthora in Maricopa and Yuma County, respectively. This survey will be continued for another year. The potential value of this information for improved disease control is discussed.
    • Effects of Canopy Position on Quality, Photosynthesis and Mineral Nutrition of Four Citrus Varieties

      Fallahi, E.; Moon, J. W. Jr.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1988-12)
      Quality, leaf gas exchange and mineral content of fruit from internal be canopies were compared with those from extemal canopy positions in 4 citrus varieties: 'Kinnow' mandarin; 'Redblush' grapefruit; 'Valencia' orange; and 'Lisbon' lemon. Fruit weight, total juice per fruit, peel fresh and dry weight, and rind thickness of fruit from internal canopies of all 4 varieties were significantly higher compared with external fruit Mandarin, grapefruit, and orange fruit from external canopies had higher soluble solids and specific gravity. Leaves from internal canopy had higher photosynthesis than those of external canopy in all varieties. Fruit from internal canopies of all varieties had generally higher peel concentrations (%dry weight) of N, P and K due to a dilution effect, while the opposite condition existed in mandarin when these elements were expressed on a percent fresh weight basis. Peel Mg and S from external fruit were higher in all varieties, expressed as percentages of either dry weight or fresh weight. Nitrogen content of mandarin and orange juice and calcium content of grapefruit and lemon juice from external fruit were significantly higher, compared to those from internal canopy fruit. Eliminating fruit quality and mineral variations resulting from canopy positions is recommended by the means of cultural practices.
    • The Effects of Navel Orange Prorate Suspension on F. O. B. to Retail Price Spreads

      Thompson, G.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1988-12)
      The effects of the navel orange prorate suspension on packinghouse to retail price spreads are analyzed When compared with price spreads for the 1986 season, F.o.b.-retail price spreads declined for Atlanta and San Francisco, but increased for Dallas.
    • Eradication of California Red Scale in Yuma County - An Ongoing Battle

      McDonald, H. H.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1988-12)
      During the last 15 years, the Yuma County Citrus Pest Control District (YCCPCD) has twice eradicated infestations of California Red Scale within the district. A third infestation, found in late 1984 is currently being fought with eradication as the goal.
    • Evaluating the Potential Threat to Citrus Plantings from Phytophthora Parasitica Originating from Noncitrus Hosts

      Matheron, M.; Matejka, J.; Butler, Marvin (College of Agriculture, University of Arizona (Tucson, AZ), 1991-01)
      The relative virulence of Phytophthora parasitica recovered from citrus and other plants to rough lemon was investigated Isolates of Phytophthora parasitica from citrus were highly virulent to rough lemon seedlings, causing crown rot and significant reduction of root weight. Isolates of the pathogen from noncitrus hosts caused slight damage to rough lemon, with no crown rot and only minor reduction of root weight. Evidently, isolates of P. parasitica from several noncitrus hosts do not pose a serious threat to citrus groves.
    • Evaluation of Citrus Front Protectant Materials

      Butler, Marvin; Matheron, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1986-12)
      With the high cost of maintaining and operating wind machines, growers are increasingly interested in alternative methods of freeze protection. Several possible frost protectant materials were applied to Valencia oranges at the Yuma Mesa Agricultural Center. Although temperatures reached the mid-to-upper 20s at the test site during the winters of 1984-1985 and 1985-1986, no frost damage occurred. As a result, it was impossible to evaluate the effectiveness of the materials.
    • Evaluation of Materials for Control of Citrus Thrips

      Butler, Marvin; Byrne, David N. (College of Agriculture, University of Arizona (Tucson, AZ), 1986-12)
      The control of citrus thrips is a major concern for citrus growers in the Yuma area. Five materials were evaluated for control of citrus thrips on Lisbon lemons at the Yuma Mesa Agricultural Center during July and August of 1985. Although there was no statistically significant differences between treatments, Mavrik appeared to provide the best control of the materials tested. Dimethoate (Cygon) and formetanate hydrochloride (Carzol) were not tested.
    • Gibberellic Acid Sizing Trial on Table Grapes, 1987

      Butler, Marvin; Rush, Bob; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Gibberellic Acid Sizing Trial on Table Grapes, 1988

      Butler, Marvin; Rush, Bob; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • Gibberellic Acid Sizing Trial on Table Grapes, 1989

      Butler, Marvin; Rush, Bob; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
    • 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)