• 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.
    • 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.
    • 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.
    • Pruning Methods Affect Yield and Fruit Quality of 'Merlot' and 'Sauvignon Blanc' Grapevines

      Kilby, Michael W.; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      One red and one white cultivar of winegrapes grown in Southern Arizona was pruned to four different methods. The red cultivar was 'Merlot' and the white was 'Sauvignon Blanc'. The pruning methods were 2 bud spur, 4 bud spur, cane and basal buds only. The basal bud treatment was eliminated for 'Sauvignon Blanc'. The 4 bud spur method resulted in significantly greater yield when compared to the other methods. Fruit produced from the basal bud only treatment resulted in fruit that was significantly greater in pH and acid content. The 'Sauvignon Blanc' cultivar had significantly higher yield with cane pruning with no difference in fruit quality.
    • 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 Scion and Rootstock Trials for Citrus in Arizona - 1997

      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)
      Five rootstocks, 'Carrizo' citrange, Citrus macrophylla, Rough lemon, Swingle citrumelo and Citrus volkameriana were selected for evaluation using 'Limoneira 8A Lisbon' as the scion. Early results indicate that trees on C. volkameriana and C. macrophylla are superior to those on other rootstocks in both growth and yield. 'Swingle' and Carrizo' are performing poorly. In a similar trial, Four 'Lisbon' lemon selections, 'Frost Nucellar', 'Corona Foothills', 'Limoneira 8A' and 'Prior' from the University of Arizona Citrus Budwood Certification plot were selected for evaluation on Citrus volkameriana rootstock. Early results indicate that the 'Limoneira 8A Lisbon' selection is outperforming the other selections in both growth and yield. Preliminary results from another lemon cultivar trial and a navel orange cultivar trial are presented as well.
    • Revitalizing "Wichita" Pecan Productivity Through Corrective Pruning - First Year Results

      Gibson, Richard; Kilby, Michael; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      A pruning study was established in stressed pecan trees to identify effective means of returning unproductive trees to full productivity. The study was comprised of two pruning systems and one untreated check. The number of nuts harvested from pruned trees was lower than that harvested from the unpruned trees, but the quality of the nuts from the pruned trees was improved when compared with the unpruned trees.
    • Seasonal Abundance and Field Testing of a Citrus Thrips Temperature Development Model in Arizona Citrus

      Rethwisch, Michael D.; McDaniel, Charles; Peralia, Manuel; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Citrus thrips populations (adults and nymphs) were monitored through the spring of 1991-1992 in several locations throughout most of the commercial citrus production areas in Yuma County to determine if citrus thrips seasonality was similar to that previously reported in California. Study findings indicate that seasonality is similar throughout the winter and very early spring. Adult thrips numbers increase rapidly in groves due to attractive foliage, whether it is weeds or citrus. High nymph numbers did not always follow adult peaks, and were not statistically correlated. Predatory mites and rains may have affected 1992 results.
    • Susceptibility of Lemons to Citrus Thrips Scarring Based on Fruit Size

      Kerns, David L.; Tellez, Tony; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1998-09)
      Lemons appear to be most susceptible to damage by citrus thrips from petal fall until they reach 1.0 inch in diameter. Correlation analysis suggests that fruit greater than 1.0 inch in diameter may not be highly susceptible to thrips scarring and thus may not require protection. 1f this relationship can be verged with additional data, late- season thrips sprays may be avoided.