• Fungicides Evaluated for Control of Powdery Mildew of Cantaloupe in 1991 Field Trial

      Matheron, M. E.; Matejka, J. C.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Leaf drop of lettuce, caused by the plant pathogenic fungi Sclerotinia sclerotiorum and S. minor. occurs every year in some lettuce fields in Arizona. When environmental conditions are favorable, disease incidence and resulting crop loss can be significant. During the 1990-1991 lettuce season in western Arizona, different fungicides and rates of materials were evaluated in the field for disease control. All tested materials increased yields compared to not using any fungicide for disease control.
    • Broccoli Variety Trials 1990/1991

      Butler, Marvin; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Dry Matter Partitioning of Cowpea (Vigna Unguiculata (L.) Walp.) Under Water Deficit Conditions

      Neto, Manoel C.; Bartels, Paul G.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Water Stress caused reduction of seed yield in cowpea plants by decreasing total biomass and photosynthesis. The source leaf, pod and seed water potential of stressed cowpea were lower than water potential in non-stressed plants. No differences in water potential and turgor were observed between pod walls and seed of cowpea plants. Partitioning of the total above ground dry matter was similar for both stressed and nonstressed cowpea plants. Photosynthetic rates of single leaves from cowpea were greater for nonstressed than stressed plants. The duration of seed growth of cowpea was not different between stressed and nonstressed plants; however, rate of seed growth at the end of seed filling period was greater in nonstressed plants. Seed growth rate of both stressed and nonstressed cowpea plants declined at about the same time photosynthesis of the source leaf declined. Leaf area index was greatest in nonstressed cowpea.
    • Broccoli Downy Mildew Tolerance Trial, 1990/1991

      Butler, Marvin; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Comparison of Capture, Capture and Thiodan, Malathion and Pounce Insecticides for Control of Two Aphid Species on Broccoli Seed

      Rethwisch, Michael D.; McDaniel, Charles W.; Major, Gary; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Evaluation of Oils, Insecticides and Insect Growth Regulators for Control of Sweetpotato Whitefly on Muskmelon and Watermelon

      Rethwisch, Michael D.; Tellez, Tony; Tellez, Alphonso; Tellez, David; Shaw, Mary; Galarza, Alex; Lastra, Luis; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Five insecticides, four oils, one soap, and two insect growth regulators were evaluated for control of sweetpotato whitefly on muskmelons and watermelons in 1990. Best control (> 80%) was noted from the insect growth regulators at 11 days post treatment, but declined thereafter. Oils as a class provided some control but not all oils provided similar results. Insecticides tested did not provide adequate control and resulted in increased whitefly egg and nymph numbers at 11 days post treatment.
    • A Pilot Project to Evaluate the Use of Geographic Information Systems (GIS) to Analyze Regional Data on Pests and Diseases of Vegetables

      Nelson, Merritt R.; Orum, Thomas V.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Geographic Information Systems (GIS) are computer databases that organize information in a spatial framework. This allows the analysis of data based in part on location. A pilot project has been set up in the Yuma Valley to explore the use of GIS to study the influence of crop sequences, weeds, urban areas, and insect vector populations on the incidence of virus diseases of vegetables. The goal is to learn to collect field observations in such a way that long term regional trends can be understood and visualized. Such information can then be used in management plans.
    • Experimental Use of Beescent® to Influence Honey Bee Visitation to Watermelon

      Loper, Gerald M.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      A commercial product called Beescent® containing a mixture of chemicals including chemicals used by honey bees as pheromones, was applied to watermelons in early bloom on Aug. 15, 1991. Honey bee visitation to treated, 18-row plots, were significantly higher than to untreated for only 2 days, the day of treatment and the next day. Watermelon yields were not effected. The daily high temperatures reached 86-88 °F, so that most of the chemical had volatilized away by the end of the first day.
    • Fungicides Evaluated for Control of Rhizoctonia Bottom Rot of Lettuce in 1991 Field Trials

      Matheron, M. E.; Leonard, R.; Major, G.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Bottom rot of lettuce, caused by the soil -borne fungus Rhizoctonia solani, can cause economic losses on early season lettuce harvested in November. First evidence of the disease is the appearance of brown, sunken, necrotic areas on the midribs of leaves touching the soil. Under favorable environmental conditions, the pathogen grows from leaf to leaf inside the head. If the fungus invades the leaves of the marketable head it and all similarly infected heads are left in the field resulting in economic losses. Field trials were established to evaluate the potential level of disease control obtainable by applying Ronilan or Rovral to lettuce beds immediately after thinning. No significant reduction in loss of marketable heads was observed in these trials, although there was a trend toward lower levels of bottom rot when either fungicide was in place.
    • Evaluation of Two Electrostatic Sprayers Compared with Conventional Application Methods for Control of Insects in Spring Head Lettuce

      Rethwisch, Michael D.; Coates, Wayne; Main, Greg; McDaniel, Charles W.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Evaluation of Imidacloprid (NTN 33893) for Control of Aphids on Broccoli

      Palumbo, J. C.; Mullis, C. H. Jr.; Reyes, F. J.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      The new insecticide Imidacloprid (NTN 33893), which is currently being developed for use on vegetable crops, was evaluated on broccoli for control of aphid species. Studies conducted in the spring of 1991 showed that this material applied postemergence as a granular formulation was extremely effective in preventing aphid colonization throughout the season. Aphid control and broccoli yields were significantly greater in plots treated with Imidacloprid. Due to low numbers of aphids in 1992, we were unable to detect differences in aphid numbers between Imidacloprid treatments and the untreated control.
    • Evaluation of Insecticides for Control of the Apache Cicada on Asparagus

      Rethwisch, Michael D.; McDaniel, Charles W.; Thiessen, James; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Five insecticides were evaluated for Apache cicada control in asparagus. Best control was achieved by two unregistered pyrethroid insecticides. The currently registered pyrethroid insecticide in this study (Pounce) was not as effective as Capture or Baythroid. Methomyl Pinnate) applied after the experiment was also very effective in controlling adult Apache cicadas. Di-Syston provided very little control.