• 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.
    • 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.
    • Sclerotinia Leaf Drop on Lettuce -- 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)
      Leaf drop of lettuce, caused by Sclerotinia sclerotiorum, is a sporadic, but destructive, disease in Arizona. Field trials were established during 1987 and 1988 to evaluate potential new fungicides for disease control. Ronilan and Rovral, the two materials currently registered for use on lettuce for Sclerotinia leaf drop, were consistently among the most effective fungicides for disease control. Levels of disease control equivalent to that provided by Rovral and Ronilan were observed with CGA-449, SC-0854 SDS-65311, Bay HWG 1608, and Spotless. These field tests have identified several potential new fungicides for control of leaf drop of lettuce caused by S. sclerotionan.
    • 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)
    • 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)
    • 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)
    • 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.
    • Vegetable Transplant Container Trial

      McGrady, John; Tilt, Phil; Oebker, Norman F.; Kingdon, Lorraine B. (College of Agriculture, University of Arizona (Tucson, AZ), 1989-05)
    • Vegetable Transplant Stress Conditioning

      McGrady, John; Tilt, Phil; 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)
    • 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)
    • 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)