• 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.
    • 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.
    • Effectiveness of Oils in Water for Leafminer Control in Fall Head Lettuce

      Rethwisch, Michael D.; Hood, Larry; Meadows, Mike; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Effects of Lettuce Insecticides Applied at Planting

      Rethwisch, Michael D.; Meadows, Michael; Hagerman, Shari; Thiessen, James; McGrady, John; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Fungicides Evaluated for Control of Sclerotinia Leaf Drop of Lettuce in 1991 Field Test

      Pier, J. W.; Doerge, T. A.; McCreary, T.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Nitrogen Management in Drip Irrigated Leaf Lettuce, Spinach and Green Crops

      Doerge, Thomas A.; Pritchard, Kevin H.; McCreary, Ted W.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Preliminary nitrogen (N) management experiments with spinach, leaf lettuce, romaine collard and mustard were conducted on a Casa Grande s.l. soil at the Maricopa Agricultural Center in the winter and spring of 1990-91. The purpose of this N rate experiment was to develop initial Best Management strategies for N fertilizer use for emerging high value crops grown in Arizona using subsurface drip irrigation. Three rates of urea, ammonium nitrate were applied to each cultivar to provide deficient (N1), adequate (N2) and supraoptimal real (N3) levels of N. All cultivars responded dramatically to the application of N. Fresh weight yields in the N1 and N2 treatments averaged 45 and 53% of the N3 treatment The average N3 yields recorded in these trials were 23.1, 12.8 and 21.8 tons of marketable produce per acre for greens, spinach and leaf lettuce/romaine crops, respectively. Preliminary plant tissue test results indicated that for all five crops, whole plant total N (TN) levels and midrib + petiole NO₃-N and leaf blade TN concentrations in the youngest mature leaf were responsive to differences in soil N supply and show promise as diagnostic N tissue test procedures. The midrib + petiole NO₃-N test appeared to be the best indicator of plant N status throughout the growing season for all five crops studied.
    • Cauliflower Variety Trials 1990/1991

      Butler, Marvin; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • 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.
    • 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.
    • Effect of Insecticides on Sweetpotato Whitefly Numbers and Growth of Broccoli

      Rethwisch, Michael D.; McDaniel, Charles W.; Shaw, Mary; Theissen, James; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Eleven treatments were applied for sweetpotato whitefly B- biotype control. Best control (62.4%) was evidenced by the Ambush + Thiodan treatment, which had fewest nymph numbers 8 days post treatment and had larger plant sizes (46.3%) 14 days post treatment than the untreated check. Plants in plots receiving treatments including Thiodan and/or Lorsban were also at least 20% larger than the untreated check. Fewest number of adult whiteflies two days post treatments were noted in the Thiodan + M-Pede treatment. Certain treatments increased whitefly numbers.
    • 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)
    • 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)
    • 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.
    • Rate by Timing Interactions of Propel on Head Lettuce

      Butler, Marvin; Hall, Don; Brooks, Dave; Oebker, Norman F.; University of Arizona; Brea Agricultural Service, Inc.; Pasquinelli Produce Company (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Evaluation of Agri-Mek with Various Oils and Adjuvents for Control of Leafminers in Spring Head Lettuce

      Rethwisch, Michael D.; Meadows, Michael; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • UA Seedless Watermelton Cultivar Trial - 1991

      Oebker, M. F.; McCreary, T. W.; Roth, R. L.; Doerge, T. A.; Pier, J. W.; Gibson, R. D.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      Seedless watermelons have become an important commodity in Arizona. In 1991 16 cultivars were compared and evaluated at the Maricopa Agricultural Center. Tri-X 313 had overall good performance and remains the standard. Several other cultivars show promise.
    • 1991 Virus Survey of Cantaloupe in Yuma

      Butler, Marvin; Brooks, Dave; Watson, Mike; Oebker, Norman F.; University of Arizona; Pasquinelli Produce (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
    • Effects of Insecticides on Leafminers, Liriomyza spp., and Associated Parasitoids on Spring Cantaloupes

      Palumbo, J. C.; Mullis, C. H. Jr.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      A study was conducted to determine the effects of repeated insecticide applications on leaf niner and parasitoid populations on spring melons. After four applications, none of the insecticides induced large build-ups of leafminer larvae. A new material, AC 303630, was very effective in maintaining low numbers of pupae. However, the results of this preliminary test indicate that all insecticides tested had a negative impact on the parasitoid population. In general, in the absence of insectcides, parasitoids were capable of maintaining L. sativae populations at low levels in the experimental plots.
    • Comparative Effectiveness of Bacillus thuringiensis Formulations Against Lepidopterous Pests of Fall Lettuce

      Palumbo, J. C.; Mullis, C. H. Jr.; Reyes, F. J.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1992-12)
      A field study was conducted at Yuma in 1991 to examine the relative effectiveness of several formulations of Bacillus thuringiensis on beet armyworm and cabbage looper on seedling and pre-cupping lettuce. Several applications were made before and after thinning. Results of the study suggest that most formulations are capable of controlling small larvae. However, because of the inherent variation in beet armyworm dispersion, it was difficult to statistically attribute differences in pest levels due to insecticide efficacy.