• Managing Septoria Leaf Spot of Pistachio in Arizona With Fungicides

      Call, Robert E.; Matheron, Michael E.; Wright, Glenn; Gibson, Rick (College of Agriculture, University of Arizona (Tucson, AZ), 2002-11)
      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 orchards. 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 June 26 and July 31, 2001. Disease severity was lowest on trees treated with Flint (trifloxystrobin) and Abound (azoxystrobin). Other materials that significantly reduced the final level of disease compared to nontreated trees included Break (propiconazole), Procop R (copper hydroxide) and Elite (tebuconazole).
    • Managing Vegetation on the Orchard Floor in Flood Irrigated Arizona Citrus Groves

      McCloskey, William B.; Wright, Glenn C.; Taylor, Kathryn C.; Wright, Glenn; Department of Plant Sciences; Yuma Mesa Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 1997-11)
      Several orchard floor management strategies were evaluated beginning in the fall of 1993 in experiments on the Yuma Mesa in a 'Limoneira 8A Lisbon' lemon grove and in a 'Valencia' orange grove at the University of Arizona Citrus Agricultural Center (CAC) in Waddell, Arizona. On the Yuma Mesa, disking provided satisfactory weed control except underneath the tree canopies where bermudagrass, purple nutsedge, and other weed species survived. Mowing the orchard floor suppressed broadleaf weed species allowing the spread of grasses, primarily bermudagrass. Pre-emergence (Solicam and Surffan) and post-emergence (Roundup and Torpedo) herbicides were used to control weeds in the clean culture treatment in Yuma. After three harvest seasons (1994-95 through 1996-97), the clean culture treatment resulted in greater yield than the other treatments. At the CAC, clean culture (in this location no pre -emergence herbicides were used,) mowed resident weeds, and Salina strawberry clover orchard floor management schemes were compared. Again the clean culture treatment yielded more than the mowed resident weeds. The yield of the strawberry clover treatment was somewhat less than the clean culture yield but not significantly less. The presence of cover crops or weeds on the orchard floor were found to have beneficial effects on soil nitrogen and soil organic matter content, but no effect on citrus leaf nutrient content. The decrease in yield in the mowed resident weed treatments compared to the clean culture treatment in both locations was attributed to competition for water.
    • Managing Vegetation on the Orchard Floor in Flood Irrigated Arizona Citrus Groves

      McCloskey, William B.; Wright, Glenn C.; Taylor, Kathryn C.; Wright, Glenn; Department of Plant Sciences (College of Agriculture, University of Arizona (Tucson, AZ), 1996-09)
      Several orchard floor management strategies were evaluated beginning in the fall of 1993 in experiments on the Yuma Mesa in a Limoneira 8A Lisbon lemon grove and in a Valencia orange grove at the University of Arizona Citrus Agricultural Center (CAC) in Waddell, Arizona. On the Yuma Mesa, disking provided satisfactory weed control except underneath the tree canopies where bermudagrass, purple nutsedge, and other weed species survived. Mowing the orchard floor suppressed broadleaf weed species allowing the spread of grasses, primarily bermudagrass. Preemergence (Solicam and Surflan) and postemergence (Roundup and Torpedo) herbicides were used to control weeds in the clean culture treatment in Yuma. After two harvest seasons (1994-95 and 1995-96), the clean culture treatment resulted in greater yield than the other treatments. At the CAC, clean culture (in this location no preemergence herbicides were used), mowed resident weeds, and Salina strawberry clover orchard floor management schemes were compared. Again the clean culture treatment yielded more than the mowed resident weeds. The yield of the strawberry clover treatment was somewhat less than the clean culture yield but not significantly less. The presence of cover crops or weeds on the orchard floor were found to modulate tree canopy temperatures, and to have beneficial effects on soil nitrogen and soil organic matter content, but no effect on citrus leaf nutrient content. The decrease in yield in the mowed resident weed treatments compared to the clean culture treatment in both locations was attributed to competition for water.
    • Mandarin Selection Trials 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)
      First year yield and packout data from a trial containing 'Fina', 'Fina Sodea', 'Sidi Aissa', 'Oroval', 'W. Murcott Afourer', 'Fremont', and 'Gold Nugget; selections were collected in 2004-05. For the year, 'Fremont' had the greatest yield, but the smallest fruit size, while 'Fina' had the smallest yield, and 'W. Murcott Afourer' had the largest fruit size.
    • Mandarin Selection Trials in Arizona - 2006-07

      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), 2007-10)
      Third year yield and packout data from a trial containing 'Fina', 'Fina Sodea', 'Sidi Aissa', 'Oroval', 'W. Murcott Afourer', 'Fremont', and 'Gold Nugget' selections were collected in 2006-07. For the year, 'Fina Sodea' had the greatest yield, and average fruit size, while 'Gold Nugget' had the smallest yield, and ‘Fremont’ had the smallest fruit size.
    • Mandarin Selection Trials 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)
      Second year yield and packout data from a trial containing ‘Fina’, ‘Fina Sodea’, ‘Sidi Aissa’, ‘Oroval’, ‘W. Murcott Afourer’, ‘Fremont’, and ‘Gold Nugget; selections were collected in 2004-05. For the year, ‘Fina Sodea’ had the greatest yield, and average fruit size, while ‘Fremont’ had the smallest yield, and the smallest fruit size.
    • Mite Control and Damage to Arizona Citrus

      Kerns, David L.; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 2003)
      Lemons were left untreated or treated for mites with Danitol (fenpropathrin). Mite populations were estimated and yield and fruit damage was accessed. Yuma spider mite, Eotetranychus yumensis, was the predominate mite species present during the high fruit susceptibility period. Although there was no apparent impact of mites on yield in this study, there was significant fruit damage that could be attributed to Yuma spider mite. The damage appeared as bronzed colored pitting of the fruit peel. Based on damage ratings, the treated plots produced 56% fancy, 34% choice, and 10% fruit grade based on mite damage, whereas the untreated plots produced 47%, 31% and 22% fancy, choice and juice grade fruit respectively. Statistically, the treated plots produce more fancy and less juice fruit, but did not differ in choice fruit. Although the treated areas produced better quality fruit, the amount of damage suffered in those plots was higher than desired. Fruit in the treated plots likely suffered some mite damage before treatments were initiated. In addition to the fruit damage test, a miticide efficacy test targeting Yuma spider mite on lemon was conducted comparing Agri-Mek, Danitol, Kelthane, Microthiol, and Nexter to an untreated check. Agri-Mek, Nexter, and Microthiol offered 14 days of control; although at 6 DAT Agri-Mek and Nexter did not differ from the untreated. Danitol and Kelthane contained fewer mite that the untreated for at least 35 DAT.
    • Molecular Basis of Rootstock-Scion Incompatibility in Macrophylla Decline May Reveal Useful Information for Screening Compatible Rootstock-Scion Combinations

      Taylor, Kathryn C.; Wright, Glenn; Department of Plant Sciences (College of Agriculture, University of Arizona (Tucson, AZ), 1997-11)
      Several differentially expressed markers of compatibility or incompatibility were isolated and are being molecularly characterized One marker is present in young Eureka on Macrophylla trees and on Macrophylla decline affected, Eureka on Macrophylla trees, while absent on healthy, Eureka on Macrophylla trees of the same combination. A second marker appears similar to a gene that encodes a Zn-binding homeodomain of a DNA binding protein in plant cells. This particular marker was found in the leaves of healthy trees, but absent in Macrophylla decline trees, which are known to be Zn deficient. Thirty-five markers are being characterized in all.
    • Mycoplasma-like Organisms as the Causal Agent for Macrophylla Decline

      Taylor, Kathryn; Ellis, Danielle; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 1996-09)
      Previous literature concerning citrus and other tree crops led us to ask if there was molecular evidence for mycoplasma -like organisms (MLOs) as the causal agent of Macrophylla decline and two other decline diseases, citrus blight and lemon sieve tube necrosis. We had molecular probes available to us that were either specific for MLOs of tree diseases and others that were universal for all known types of MLOs. We used a polymerase chain reaction (MLO) to determine if MLOs were present in the vascular tissues of decline and healthy citrus. I all trials performed, the trees were negative for MLO-PCR products. In addition, we attempted to transmit putative MLO 's from decline affected trees to Vinca rosea MLO-nurse plants. We were unable to affect this type of transfer. In addition, our attempts to identify MLO's in phloem tissue gave us negative results. We have since revised our hypothesis. We are currently pursuing the hypothesis that these decline disorders are the result of a rootstock scion incompatibility, that we may be able to avoid culturally, while maintaining these valuable combinations.
    • Nitrogen and Phosphorus Fertilizer Management for Young, Bearing Microsprinkler-Irrigated Citrus, Final Report

      Thompson, Thomas L.; White, Scott A.; Kusakabe, Ayako; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 2005)
      Higher nutrient and water use efficiency are possible with microsprinkler-irrigated citrus compared to flood-irrigated citrus. Therefore, new N and P fertilizer recommendations are needed for microsprinkler-irrigated citrus. The objectives of this project were to i) determine the effects of N applications of 0 - 0.8 lb/tree/yr on fruit yield, fruit and juice quality, and N and P removal in fruit for microsprinkler-irrigated navel oranges; ii) determine the effects of P applications of 0 - 0.2 lb/tree/yr on fruit yield, fruit and juice quality, and N and P removal in fruit, and iii) develop Best Management Practices for N and P fertigation of microsprinkler-irrigated citrus. Field experiments were conducted at the University of Arizona Citrus Agricultural Center in separate blocks of ‘Newhall’ and ‘Fukumoto’ navel oranges, both on ‘Carrizo’ rootstock. In each block, ten treatments, consisting of all possible combinations of 5 N rates (0, 0.2, 0.4, 0.6, and 0.8 lb N/tree/yr) and 2 P rates (0, 0.2 lb P/tree/year) were applied to five replicate trees per treatment. The maximum predicted yields for both varieties during all three seasons occurred at N rates of 0.4 to 0.55 lb N tree-1 yr-1. There were no significant effects of P application on fruit yield or quality. There were few significant effects of N or P fertilization on packout or fruit quality. The amounts of N removed in harvested fruit at the yield-maximizing N rates were equivalent to 50-84% of the N applied. New N fertilizer recommendations for microsprinkler-irrigated navel oranges are proposed.
    • Nitrogen and Phosphorus Fertilizer Requirements for Young, Bearing Microsprinkler-Irrigated Citrus, 2005 Report

      Thompson, Thomas L.; White, Scott A.; Kusakabe, Ayako; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 2004)
      Higher nutrient and water use efficiency are possible with microsprinkler-irrigated citrus compared to flood-irrigated citrus. Therefore, new N and P fertilizer recommendations are needed for microsprinkler-irrigated citrus. The objectives of these experiments were to i) determine the effects of N applications on tree growth, fruit yield, fruit and juice quality, and N and P removal in fruit for microsprinkler-irrigated navel oranges; ii) determine the effects of P applications on tree growth, fruit yield, fruit and juice quality, and N and P removal in fruit, and iii) develop Best Management Practices for N and P fertigation of microsprinkler-irrigated citrus. Field experiments were conducted at the University of Arizona Citrus Agricultural Center in separate blocks of 'Newhall' and 'Fukumoto' navel oranges, both on 'Carrizo' rootstock. In each block, ten treatments, consisting of all possible combinations of 5 N rates (0, 0.2, 0.4, 0.6, and 0.8 lb N/tree/yr) and 2 P rates (0, 0.2 lb P/tree/year) were applied to five replicate trees per treatment. Maximum yields of the ‘Newhall' trees were 132 lb fruit/tree at a N rate of 0.5 lb N/tree/yr. Maximum yield of the 'Fukumoto' trees was119 lb fruit/tree at 0.5 lb N/tree/yr. Both varieties maintained appropriate leaf N and P concentrations at the yield-maximizing N rates. Total N in the fruit accounted for about 60 % of the N applied at the yield-maximizing N rates in both varieties. The results confirmed that microsprinklers effectively reduced the amounts of N fertilizer needed while maintaining adequate N status in the trees, with excellent N use efficiency.
    • Nutrition Survey in Arizona Citrus

      Taylor, Kathryn C.; Wright, Glenn (College of Agriculture, University of Arizona (Tucson, AZ), 1996-09)
    • Nutritional Status of Wine Grap Cultivars Grown in Southern Arizona

      Kilby, Michael W.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Ten winegrape vineyards consisting of different cultivars were leaf petiole sampled at bloomtime. Petioles were analyzed and results composited for the survey. There were indications that boron, iron, nitrogen and phosphorus were nutrients where potential problems (deficiencies) were likely to occur. This survey supplied information for the basis of developing a monitoring program on an annual basis.
    • Organic Lemon Production

      Zerkoune, Mohammed; Wright, Glenn; Kernz, David; McCloskey, William; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2002-02)
      This experiment was initiated in March 2000 to study the feasibility of growing organic lemon in the desert southwest of Arizona. A ten-acre field planted to lemons in 1998 was selected on Superstition sand at the Yuma Mesa Agricultural Research Center. The initial soil test in top 6 inches was 5 parts per million (ppm) NO₃⁻ and 4.9-PPM NaHCO₃⁻-extractable P. Soil pH was 8.7 in the top 6 inches. Seven treatments were applied in randomized complete block design repeated three times. The treatments were control, compost and clover, compost and perfecta, compost and steam, manure and clover, manure and perfecta and manure and steam Leaf tissue analysis indicated that nitrate level was significantly influenced by treatment. Organic insect control treatments for citrus thrips were as equally effective as the non-organic commercial standards.
    • Particle Film Technologies: Pest Management and Yield Enhancement Qualities in Lemons

      Kerns, David L.; Wright, Glenn C.; Wright, Glenn (2003)
      Surround WP and Snow were evaluated for their ability to manage citrus thrips populations in lemons on the Yuma Mesa, and their impact on lemon yield, fruit quality, and packout. Both Surround and Snow effectively controlled citrus thrips and prevented fruit scarring. Surround produced higher yields than either Snow or the commercial standard at the first harvest (#9 ring). There were no differences in yield among treatments for the second (strip) harvest, nor were their any differences in total yield. These data suggest that Surround may increase fruit earliness or sizing. There were no statistical differences among any of the treatments in fruit size frequency or quality for any of the harvests, and there was no apparent benefit from applying an additional application of Surround or Snow post thrips season solely for quality, fruit size, or yield enhancement. The activity of Surround does not appear to be adversely affected by the inclusion of the insecticides Danitol, Baythroid, Carzol, or Success, nor do these insecticides appear to be adversely affected by Surround. Foliar fertilizers did not appear to adversely affect the activity of Surround when tank mixed. However, there is some evidence that Surround may negatively affect the absorption of Fe and Mn when tank mixed with Zn, Fe, Mn lignosulfonate, but this data is not conclusive. The addition of a non-ionic surfactant appears to enhance the on-leaf distribution of Surround over light petroleum and paraffin based oils, but long term efficacy is not affected.
    • Pecan Leaf Tissue Nutrient Concentrations: Temporal Relationships and Preliminary Standards

      Walworth, James; Kilby, Michael; Wright, Glenn; Gibson, Rick (College of Agriculture, University of Arizona (Tucson, AZ), 2002-11)
      Leaf samples were collected from five trees each of Bradley, Cheyenne, Sioux, Western Schley, and Wichita at Picacho, Arizona and five trees each of Bradley, Western Schley, and Wichita at Las Cruces, New Mexico, and analyzed nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, manganese, boron, and copper at two-week intervals from mid-May to Mid-October, 2000. Yield, average nut weight, and percent kernel data were collected for each individual tree. Leaf tissue analysis indicated that concentrations of nitrogen, phosphorus, potassium and sulfur decreased. The overall trends were for zinc levels to declined, although they increased at the end of the season. Boron, calcium, magnesium and manganese, and iron concentrations increased during the growing season. Copper concentrations were variable. Preliminary nutrient standards are presented and compared to existing standards. Most nutrients were within recommended ranges, but magnesium levels were much higher than the top of the Arizona and New Mexico sufficiency ranges. Manganese was higher than the Arizona sufficiency range, but within that of New Mexico, whereas zinc was higher than the New Mexico range, but within that of Arizona.
    • Pecan Variety Study on the Safford Agricultural Center

      Clark, L. J.; Carpenter, E. W.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      In 1986 a replicated study of eight varieties of pecans was planted on the Safford Agricultural Center at an elevation of 2954 feet above sea level. The objective of the study was to determine which varieties would produce best under the saline conditions found in the Safford valley. WO-3, the highest overall producer of the study, produced the best yield in 1999, with a yield over 2600 pounds per acre. This paper also contains kernel percentages and other nut characteristics found in the study during the 1999 harvest seasons and a summary of the yields since 1997.
    • Pecan variety study on the Safford Agricultural Center 1997-1998

      Clark, L. J.; Carpenter, E. W.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      In 1986 a replicated study of eight varieties of pecans were planted on the Safford Agricultural Center at an elevation of 2954 feet above sea level. The objective of the study was to determine which varieties would produce best under the saline conditions found in the Safford valley. This paper contains yield, kernel percentages and other nut characteristics found in the study during the 1997 and 1998 harvest seasons. Cheyenne and WO-3 were the highest yielding varieties in 1997 and 1998, respectively. The respective yields were 1894 and 2286 pounds per acre.
    • Pecan yields and nut quality as influenced by soil trenching and tree pruning

      Gibson, Richard; Nunan, Linda; Kilby, Michael; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      Trenching and pruning applications were placed on mature Wichita pecan trees in Maricopa, Arizona in 1998. Yield and nut quality data from the test are presented. Unfortunately, the cool, favorable growing weather minimized quality degradation during the growing season and confounded the test. Data presented probably do not reflect the true benefits of the treatments.
    • Performance of mature pecan varieties in the low desert 1997 and 1998

      Gibson, Richard; Nunan, Linda; Kilby, Michael; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      Mature pecan trees at Picacho, Arizona were evaluated for variety performance during 1997-98. Total average yield per tree, percent kernel and percent viviparity were observed. During 1997, a severe viviparity year, only Bradley, Cheyenne, Souix and Tejas showed viviparity values of 20% or lower. Tejas did not return an acceptable percent kernel leaving Bradley, Cheyenne and Souix as potential varieties able to withstand low desert growing conditions on a regular basis. In 1998, the cool growing season confounded the test and no conclusions were drawn from the data.