• Yuma Broccoli Variety Trials, 1987-1988

      Butler, Marvin; Oebker, Norm; Davis, Jackson; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Enhanced Growth of Drip Irrigated Sweet Corn Using a Nitrification Inhibitor

      Doerge, Thomas A.; Tucker, Thomas C.; McCreary, Ted W.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
      A field experiment using subsurface drip irrigation was conducted at the Maricopa Agricultural Center on a Casa Grande sandy loam to evaluate the effect of varying nitrogen rates on the growth and yield of 'Jubilee' sweet corn when applied with, and without the nitrification inhibitor, nitrapyrin (N-Serveᴿ). N treatments of 89, 134 and 2671bs. N/acre were applied as ammonium sulfate to one meter miniplots in three split applications between the V2 and the V10 growth stages. Individual N-Serveᴿ application rates were 0.5 lbs/acre. All solutions were applied through buried, perforated PVC tubing to simulate application through the buried drip irrigation system. The inclusion of N-Serveᴿ significantly increased dry matter accumulation, number of total ears and number of marketable ears /plant at all N levels. Plant tissue analysis suggested that enhanced uptake of ammonium -N as well as reduced leaching of nitrate-N contributed to this growth response to N- Serveᴿ.
    • Asparagus Response to Water and Nitrogen

      Roth, Robert L.; Gardner, Byrant R.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
      The relationships of asparagus yields to varying levels of water and nitrogen were determined. Maxinuem yields of 345, 560 and 300 crates/acre were produced for asparagus crowns that were 3, 4 and 5 years old, respectively. A total seasonal water depletion rate of 98 inches was calculated for the fern growing season. Optimum nitrogen applications were estimated at approximately 350 -400 lb/ac.
    • Vegetable Transplant Stress Conditioning

      McGrady, John; Tilt, Phil; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Resistance in Cultivated and Wild Lettuce to Lettuce Infectious Yellows Virus

      Ray, Dennis T.; McCreight, James D.; McGrady, John J.; Brown, Judith K.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
      In 1988, Arizona's early- season lettuce crop was plagued by disease and insect problems, both intensified by unseasonably high temperatures. In the western Arizona production area, an epidemic of lettuce infectious yellows (LIY) resulted in serious economic losses to growers. The yellows disease is incited by the LIY virus (LIYV), a plant virus transmitted by the sweet potato whitefly [Bemisia tabaci (Gene.)]. Disease symptoms in lettuce include stunted growth, rolling yellowing and /or reddening of infected leaves; necrotic lesions appear at or near the leaf margins at latter stages of the disease. LIYV has a wide host range which increases the difficulty of isolating lettuce fields from LIYV infected or whitefly-infested fields; also, whiteflies are resistant to insecticides. Therefore, host-plant resistance appears to be the most promising means of reducing losses due to this disease. To initiate a breeding program, commercial lettuce cultivars and breeding lines (Lactuca sativa L.), and related, cross-breeding wild lettuce species (L. serriola L. and L. saligna L.) were screened for resistance to LIYV in the western Arizona production area using natural inoculation by residence whiteflies.
    • Evaluation of Head Lettuce Varieties for Liriomyza trifolii Leafminer Populations

      Rethwisch, Michael D.; Butler, Marvin D.; Meadows, Mike; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Control of Liriomyza trifolii Larvae in Head Lettuce

      Rethwisch, Michael D.; Winans, S. Sherwood; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Sweet Corn Cultivar Evaluations in Arizona, 1987-1988

      Oebker, Norm; Harper, Fred; Bessey, Paul; Gibson, Rick; White, Marcia; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Detection of Lettuce Infectious Yellow Virus (LIYV) in Greenhouse and Field Inoculated Plots Using an Indirect Enzyme-linked Immunosorbent Assay (Indirect ELISA)

      Brown, Judith K.; Poulos, Bonnie T.; Costa, Heather S.; Nelson, Merritt R.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
      Lettuce infectious yellows virus (LIYV), a recently recognized plant virus, causes dramatic yellowing symptoms and severe diseases in a wide range of vegetable crops in Arizona, adjacent southwestern states and Mexico. Until now, the only available diagnostic method was a time-consuming bioassay that used the insect vector to transmit the virus, with subsequent manipulation of indicator plants. A rapid, sensitive diagnostic technique (termed an indirect enzyme-linked immunoassay, called indirect ELISA) system was developed to detect lettuce infectious yellows virus (LIYV) in infected plant material. A virus specific antibody was made to viral capsid protein which was purified by polyacrylamide gel electrophoresis. The indirect ELISA system was optimized and used to detect viral antigen in greenhouse-inoculated melons. The system was subsequently adapted to detect LIYV in symptomatic and asymptomatic weed and cultivated plant species collected from infected fields near Yuma and in central Arizona. The indirect ELISA system described here allows for the detection of approximately 100 ng of virus per well. The LIYV was detectable in symptomatic (but not in asymptomatic) leaves of melon plants infected with the virus. In contrast, the virus could be detected in both symptomatic and symptomless cheeseweed plants collected in the field. The optical density readings for infected weed species were generally lower than those for cultivated species, such as melons, lettuce, and spinach, suggesting that there is less virus in the weed hosts tested than in infected, cultivated hosts.
    • Use of Stylet Oil to Slow the Spread of Lettuce Infectious Yellows Virus

      Nelson, Merritt R.; Matejka, Joseph C.; Brown, Judith K.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
      The use of stylet oil to slow the spread of the whitefly- transmitted vines, lettuce infectious yellows, shows sufficient promise to plan for expanded research efforts. The main positive results were a slower buildup of virus infection and a larger number of marketable heads in the block of lettuce sprayed with oil. Weight (in grams) of individual heads could be correlated with time of infection in that the lowest weights and marketability ratings occurred in plants infected earliest in the season. Whether they were front treated or untreated plots, marketable heads weighed an average of 784 grams; unmarketable heads weighed 491 grams. The key difference is that, on the average, five marketable heads of lettuce were in the oil- treated plots for every three in the untreated plots. A follow-up experiment will be conducted in 1989 to determine if these preliminary positive results indicate that stylet oil treatment may be a practical control method for slowing the spread of L1YV.
    • Powdery Mildew of Cantaloupe -- Evaluation of New Fungicides for Disease Control

      Matheson, Michael E.; Matejka, Joseph C.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
      Powdery mildew of cantaloupe, caused by Sphaerotheca fuliginea, is a perennial and often devastating disease in Arizona. During 1987 and 1984 potential new fungicides were evaluated in field trials for disease control. In 1987, Bayleton, Rally and Spotless provided significant disease control. In 1984, Rally and Spotless significantly reduced development of powdery mildew, while Bayleton and Tilt were less effective. Uneven development of powdery mildew within the plot may partially explain the apparent lack of significant disease control in 1988 by Bayleton and Tilt.
    • A Study of Timing of Sweet Corn Plantings for Fall Harvest in Central Arizona

      Oebker, Norman F.; White, Marcia; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Tolerance of Terpary and Navy Beans to Different Salt Levels in Irrigation Water

      Podziewski, Judy; Coons, Janice; Lormand, Kate; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Effect of Gypsum on Lettuce in Marana, 1988

      Thacker, Gary W.; Doerge, Thomas A.; Oebker, Norman P.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
      Gypsum was applied preplant on spring lettuce at rates of zero, 2 tons per acre, and 4 tons per acre. There were no significant differences in carton yields or in carton weights. Postharvest soil analyses showed that the application of four tons of gypsum per acre significantly increased the calcium and magnesium levels in the saturated paste solution. There were no significant effects of gypsum application on ESP and SAR values, nor in pH or sodium concentrations.
    • Leafminer Fly New to Arizona Spreads Across State, Causes Severe Damange to Lettuce

      Rethwisch, Michael D.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Weed Control Investigations in Deserted Irrigated Asparagus

      Nigh, Edward L. Jr.; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Vegetable Transplant Container Trial

      McGrady, John; Tilt, Phil; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • International Asparagus Cultivar Trial

      McGrady, John; Nelson, John; Nichols, Mike; Tilt, Phil; Hart, Garry; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Yuma Cauliflower Variety Trials, 1987-1988

      Butler, Marvin; Oebker, Norm; Davis, Jackson; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Honeydew Measles: A Potential Threat to Commercial Honeydew Production

      Brown, Paul; Gibson, Richard; Oebker, Norman; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
      Measles of honeydew melons is not a common problem, but melon growers should be aware that it can cause severe economic damage, under the right environmental conditions. At least one Pinal County grower suffered significant loss during an outbreak of this disease in September 1987.