• Effects of Various Chemicals on Dormancy, Maturity and Thinning of Peaches

      Fallahi, Esmaeil; Kilby, Michael; Moon, John W.; Kilby, Michael W.; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990-12)
      Effects of 5 chemicals on the reduction of dormancy and early maturity of peaches were studied for 3 years under the desert climatic condition of Southwest Arizona. CuSO4, urea and particularly hydrogen cyanamide reduced the dormancy and enhanced blooming. Application of hydrogen cyanamide in October induced full bloom in November (1 month after application) and produced fruit. Late November was the most appropriate time for application of hydrogen cyanamide, and fruit were harvested 10 days before normal time in April. No difference was found between 5% and 3% (V/V) of hydrogen cyanamide in the time of blooming; however, rate at 5% always caused some phytotoxicity. Application of hydrogen cyanamide at 1% before bloom and at full bloom produced the same size of commercially packed fruit as hand-thinned ones.
    • 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.
    • 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 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.
    • Performance of Mature Pecan Varieties in the Low Desert of Pinal County 1997-1999

      Kilby, Michael; Gibson, Richard; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Twelve varieties of pecans were evaluated for yield, viviparity, and nut quality. The commercially recommended varieties 'Western Schley' and 'Wichita' produced the greatest yields but also had the highest percentage of pregermination. The varieties 'Cheyenne' and 'Sioux' exhibit great potential for commercial production in the low desert of Arizona.
    • Population Dynamics of Pecan Aphids and Their Green Lacewing Predators in Insecticide-Free Pecans

      Hunter, Martha; Petersen, Mette; McElween, Melinda; Kilby, Michael; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Field surveys of aphids and their natural enemies were conducted in a 30 acre unsprayed block of 'Wichita' pecans in Southeastern Arizona (FICO, Sahuarita) during the growing seasons of 1997, 1998, and 1999. Each season showed a different pattern of aphid population development. In general, numbers of the more damaging black pecan aphid, Melanocallis caryaefoliae were always lower than those of the blackmargined pecan aphid Monellia caryella and no serious aphid damage by either species was observed. Two species of green lacewings were the dominant natural enemies in the orchard, and eggs could be found throughout the season.
    • Rejuvenation of mature pecan trees by pruning

      Kilby, Michael; Gibson, Richard; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1999-11)
      Neglected mature 'Wichita' pecan trees were rejuvenated using various pruning techniques in 1997. Trees were pruned using proven horticultural techniques which included dehorning (cutting main scaffolds to within 2 feet of trunk) and cutting main scaffolds by 50%. To date the treatments have resulted in an increase in yield when compared to trees that received no pruning. In 1999 the grower has developed an orchard management program conducive to maximum production.
    • Rejuvenation of Neglected, Mature "Wichita" Pecan Trees By Corrective Pruning

      Gibson, Richard; Kilby, Michael; Wright, Glenn; Kilby, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 2002-02)
      An attempt was made in 1997 to rejuvenate neglected, mature 'Wichita' pecan trees in a commercial Pinal County grove by applying two types of heading back pruning cuts. The treatments were applied during the dormant season prior to the growing season. The trees were pruned using proven horticultural techniques which included dehorning (cutting main scaffolds to within 2 feet of the trunk) and cutting main scaffolds by 50%. After four years of data, the trees receiving no pruning treatments are producing as well or better than trees to which the pruning treatments were applied. The data suggests that a return to normal irrigation and fertilization practices alone will return neglected, water-stressed trees to normal productivity as early as trees that have been headed-back.
    • 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.