• Yuma Vegetable Variety Trials 1996/1997

      Wilcox, Mark; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
    • Evaluation of Postemergence Herbicides for Broccoli Weed Control

      Umeda, K.; Stewart, D.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Second year field studies continued to evaluate and determine efficacy and safety of postemergence herbicides for broccoli weed control. Goal® 2XL. a newly introduced formulation of oxyfluorfen. severely injured broccoli after application. London rocket (Sisvmhrium irio) control was not acceptable at less than 80%. Pvridate (Lentagran®) and clopyralid (Stinger®) were relatively safe on broccoli but did not affect London rocket.
    • Field Evaluation of Head Lettuce Cultivars for Susceptibility to Sclerotinia Leaf Drop in 1997

      Wilcox, Mark; Matheron, Michael; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Leaf drop of lettuce is caused by the plant pathogenic fungi Sclerotinia minor and S. sclerotiorum. Cool and moist environmental conditions favor disease development. Sixteen diffirent cultivars of head lettuce were evaluated in the field for susceptibility to Sclerotinia leaf drop in plots inoculated with sclerotia of Sclerotinia minor or S. sclerotiorum. Significant differences were detected among the tested cultivars in the amount of lettuce plants killed by Sclerotinia minor. On the other hand, there were no significant differences among tested cultivars in the number of plants destroyed by Sclerotinia sclerotiorum
    • DPX-MP062 (DuPont) Insecticide Efficacy in Broccoli Study

      Umeda, K.; Stewart, D.; Murrieta, J.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      DPX -MP062 (Dupont) insecticide was applied two times in broccoli for cabbage looper (Trichoplusia ni. CL) control and demonstrated efficacy comparable or superior to methomyl (Lannate®) or esfenvalerate (Asana®). DPX-MP062 0.025 to 0.065 lb AI/A alone or in combination with Lannate significantly reduced the number of medium to large sized CL larvae relative to the untreated broccoli following each application.
    • Yuma Cantaloupe Variety Trial 1997

      Wilcox, Mark; Oebker, Norman F.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
    • Evaluation of Nortron® Herbicide for Preemergence Weed Control in Onions

      Umeda, K.; Gal, G.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      An exploratory field study was conducted to evaluate the efficacy and safety of Nortron® (ethofumesate) herbicide for potential use in an onion weed control program. A rate range of 1.0 to 2.5 lb AI/A applied preemergence (PREE) demonstrated good safety on onions and no injury or crop stand reduction was observed. Sowthistle was the most numerous weed present and Nortron did not reduce it relative to the untreated check. Dacthal® (DCPA) significantly reduced the number of sowthistle relative to the untreated and to Nortron treatments. Onion height was reduced by Dacthal about 40 %.
    • Management of Lepidopterous Larvae Under Experimental, Biorational and Conventional Control Programs in Lettuce

      Palumbo, John C.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      A large block experiment was conducted at the Yuma Ag Center to compare the field performance of three lettuce management programs for control of lepidopterous larvae. Conventional, experimental and biorational insecticides were sprayed to control beet armyworm, cabbage looper and Heliothis species throughout the growing season. Differences in populations of total larvae among the four treatments, relative to insecticide treatments and timing of application were observed throughout the season. In general, the standard and experimental treatments provided the most consistent control of lepidopterous larvae following each application. Harvest data showed that the spray regimes had a significant influence of head lettuce yield or quality. Maturity and quality were significantly reduced in the untreated control. An economic analysis shows that net returns varied widely among the management programs at different market prices. In conclusion, this study provides preliminary data to support the need for more development of experimental and biorational insecticide products as alternatives to conventional management programs in desert lettuce production.
    • Field Emergence and Seedling Growth of Lettuce as Affected by Pre-Plant/Pre-Emergent Herbicides

      Sill, David W.; Tickes, Barry; Carey, Lisa A.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Pre plant and pre- emergence herbicides are commonly used in lettuce production. We investigated possible effects the herbicides benefin (Balan), pronamide (Kerb) and bensulfide (Prefar) had on emergence and seedling growth of several iceberg lettuce varieties that had been primed and pelleted by seed enhancement companies The herbicide Prefar and a mixture of Balan + Prefar had the greatest impact on dry weight regardless of variety, while seedlings grown on Kerby plots were not significantly different than seedlings from untreated plots. Dry weight accumulation and field emergence were influenced significantly by pellet types and priming methods.
    • Powdery Mildew of Cantaloupe: Comparison of Chemical Management Tools in 1996

      Matheron, Michael E.; Porchas, Martin; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Powdery mildew of cantaloupe and other melons occurs every year in Arizona; however, the incidence and severity of the disease is quite variable. This disease, caused by the plant pathogenic fungus Sphaerotheca fuliginea, is favored by moderate temperature and relative humidity, succulent plant growth and reduced light intensity. Potential new fungicides were evaluated for disease management in a field trial conducted in the spring of 1996. All tested products significantly reduced the level of disease compared to nontreated melon plants. In addition to compounds already registered for use on cantaloupe, such as Microthiol Special, Reach, Benlate, Bayleton and Bravo, the list of efficacious nonregistered agrochemicals included Quadris, Procure, BAS-490, and Rally. The possible availability of new disease management tools in the future for powdery mildew of cantaloupe and other melons could enhance our efforts to reduce the development of resistance to these fungicides by the pathogen.
    • Temporal and Diagnostic Mortality of Beet Armyworm Larvae to Selective Insecticides in Head Lettuce

      Palumbo, John C.; Kerns, David L.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Several new insecticide chemistries were evaluated and compared with standard chemistries for temporal and diagnostic mortality of beet armyworm in lettuce. Field and lab bioassays of small and large armyworm mortality were conducted at pre- thinning thinning postthinning and harvest stages of lettuce. Results from both the field and laboratory indicated similar trends for the temporal activity of the products. The compounds with translaminar activity (Alert, Success, and Proclaim) appear to be have the most rapid "knockdown activity" with 100% mortality consistently occurring by 1-2 DAT. Because of their rapid activity, a large proportion of larvae are found dead on the plants. The products that need to be ingested to cause larval mortality (Larvin, Confirm, Neemix, Crymax, Cryolite, MP 062) generally varied significantly in temporal mortality and in efficacy against larvae. Unlike the translaminar products, a large proportion of larvae on were often found missing from treated plants The results of this study provide basic guidelines concerning the activity and assessment of the performance of these materials in the field PCAs and growers will ultimately be able to develop specific use patterns for these materials within their individual lettuce pest management programs.
    • Evaluation of Summer Cover Crops for Rotations with Vegetable Crops

      Umeda, K.; Munda, B.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Five different crops were evaluated in exploratory and observational field studies for potential use as a summer cover crop in a rotation with commonly grown vegetable and field crops. Sesbania ( Sesbania exaltata), cowpea (ViRna unguiculata), sunnhemp (Crotalaria iuncea var. Tropic Sun), sudangrass (Sorghum sudanense cv. Piper), and kenaf (Hibiscus cannabinus) were drill seeded and grown with 2-3 irrigations during the summer months in two field tests. In one test, fresh weight yields were: 7,794 lb/A for sesbania; 10,551 lb/A for sunnhemp; 5,184 lb/A for cowpea; 19,816 lb/A for sudangrass; and 2,390 lb/A for kenaf General observations indicated that adult whiteflies were attracted to sunnhemp at one test site but not at the other. Broccoli, cabbage, and barley were planted in the fall following the cover crops and general observations indicated that sudangrass significantly reduced all of the crops' stand and measurable responses were not evident where the other cover crops were planted.
    • Insecticides for Whitefly Control in Cantaloupes

      Umeda, Kai; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Several experimental insecticide treatments alone or in combinations were evaluated and demonstrated efficacy against Bemisia argentifolii [silverleaf whitefly (WF) also known as sweet potato WF, B. tabaci]. At each rating date following each of four applications, the number of adult and immature WF were reduced relative to the untreated check CGA-215944 (Ciba) treatment combinations were similar at each rating date and significant differences could not be distinguished between the addition of fenoxycarb (Ciba) or CGA-59205 (Ciba). Combinations of insecticides or alternating with insect growth regulators (IGR's) also significantly reduced numbers of WF adults and immatures similar to the standard treatment of bifenthrin (Capture®) plus endosulfan. A single application of pyriproxyfen (Valent) was followed by different treatments [endosulfan followed by fenpropathrin (Danitol®) plus methamidaphos (Monitor®) followed by endosulfan] at each application date. Buprofezin (Applaud®) was combined or alternated with endosulfan at each application and similar reduction of WF was observed. Pyridaben (BASF) did not adequately reduce WF adults and immatures relative to the standard treatment in this test. The Ciba compounds and single or multiple applications of the IGR's, pyriproxyfen and Applaud were highly effective in substantially reducing WF immatures and adults in this test.
    • Lannate and Larvin Resistance in Beet Armyworms from the Low Desert Regions of Arizona and California

      Kerns, David L.; Tellez, Tony; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Beet armyworm populations were collected in 1996-97 from spinach, melons, lettuce and alfalfa in Arizona and California, and tested for resistance to topical applications of Lannate. Resistance levels were found to be low to very high. The lowest level of resistance detected came from Blythe, CA, having no detectable resistance to Lannate, and from Parker, AZ, having a resistance level of approximately 24 fold. The highest level of resistance detected was a 685 fold increase, from a population collected from alfalfa in Imperial County, CA. In Yuma, larvae collected from alfalfa following an insecticide application that included Lannate, was 4.43 fold more resistant than the pre-application population. Only very low levels of resistance were found to Larvin, and no evidence of cross -resistance between Lannate and Larvin was found. Larvae resistant to topical applications of Lannate were found to be susceptible to Lannate given orally. Lannate resistance appears to be due to cuticular penetration and/or cuticular metabolism.
    • Commercial Evaluation of Proclaim for Control of Lepidopterous Pests of Lettuce

      Tellez, Tony; Kerns, David L.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Proclaim 1.6 was evaluated in head lettuce in side-by-side large plot aerial and ground application demonstrations compared to commercial standard treatments. Proclaim consistently provided excellent control of beet armyworm and cabbage looper larvae. Worm control by Proclaim was equivalent to, or better than the commercial standards.
    • Evaluation of Conventional and Experimental Insecticides for Control of Western Flower Thrips in Head Lettuce

      Palumbo, John; Mullis, Clayton Jr.; Reyes, Francisco; Amaya, Andreas; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Studies were conducted in small plot field trials to evaluate the efficacy of several experimental and conventional insecticide chemistries against western flower thrips in head lettuce. Results from two trials using new experimental compounds showed that several insecticides have potential for management of thrips populations. All of the products appear to be good candidates for thrips control and had efficacy against adults and nymphs. Success and Fipronil consistently provided comparable control to the standard Lannate/Ammo. In the trial evaluating conventional compounds, Orthene/Mustang and Lannate/Ammo combinations provided the best control of both adult and nymphs. Plant size and temperature may be important factors contributing to the efficacy of these products.
    • Lepidopterous Insect Pest Control with New Insecticides in Cabbage

      Umeda, K.; Murrieta, J.; Stewart, D.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Four experimental insecticides being developed for lepidopterous insect control in vegetable crops were applied on cabbage and demonstrated efficacy against cabbage looper (Trichoplusia ni, CL). Chlorfenapyr (Alert®), tebufenozide (Confirm®), spinosad (Success®), and emamectin- benzoate (Proclaim®) reduced the number of larger cabbage loopers following multiple applications. The experimental insecticides were comparable or superior to the commercially available standard treatments of thiodicarb (Larvin®), methomyl (Lannate®), or cryolite (Kryocide®). Evaluations at 7 days after treatment (DAT) showed that Success controlled CL so that no medium to large -sized larvae were observed. Alert, Confirm, and Proclaim were highly effective and less than 0.3 CL/plant were detected. The untreated cabbage had 0.5 to 1.1 CL/plant that were medium to large-sized at various observation dates.
    • Seasonal Dynamics and Management of Whiteflies on Melons and Vegetables in the Desert Southwest

      Palumbo, John C.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      For the past 5 years, Arizona growers have been faced with the challenge of managing whiteflies populations to prevent yield reduction and loss of quality of their vegetable and melon crops. A large cooperative research effort was directed statewide to better understand how whiteflies develop on the numerous host -crops available and the environmental factors that influence their survival throughout the year. This information was used to develop short and long term management approaches for controlling whitefly populations. We quickly discovered that preventing whiteflies from colonizing plants was the key to successful management of whitefly populations in vegetable and melon crops. This report attempts to summarize what we presently understand about factors that influence the seasonal abundance of whiteflies in southern Arizona cropping systems. Non-chemical and chemical management approaches that have been developed by researchers and implemented by the agricultural communities are discussed
    • Mating Disruption of Beet Armyworm in Lettuce by Synthetic Pheromone

      Kerns, David L.; Tellez, Tony; Nigh, Jeff; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      The beet armyworm pheromone dispenser, Yotoh-con-S, was evaluated for its ability to inhibit mate location and subsequent population growth of beet armyworm in head lettuce. Pheromone dispensers were very effective in preventing male beet armyworm moths from locating point pheromone sources. Pheromone dispensers also appeared to result in an approximately 75 % reduction in beet armyworm larvae relative to untreated fields.
    • Commercial Evaluation of Confirm for Control of Lepidopterous Pests of Lettuce using Various Applications Techniques

      Kerns, David L.; Tellez, Tony; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Confirm was evaluated in head lettuce for control of lepidopterous pests when applied by air, and when applied by ground at 4, 8 and 12 mph. By air Confirm may not provide commercially acceptable control when used alone. Confirm must be ingested to exhibit activity and aerial applications may not provide adequate spray coverage. When used by ground, applicators should avoid exceeding 8 mph, again because good spray coverage may be compromised.
    • Evaluation of Foliar Insecticide Approaches for Aphid Management in Head Lettuce

      Palumbo, John; Mullis, Clayton Jr.; Reyes, Francisco; Amaya, Andreas; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Provado insecticide (imidacloprid) was compared to Admire and other standard insecticides for management of aphids in head lettuce in Yuma 1995 and 1996. Foliar applications of Provado appear to provide an alternative method of controlling aphids on lettuce comparable to prophylactic applications of Admire. The prevention of aphid colonization in lettuce heads with Provado may depend greatly on the timing and frequency of applications before harvest occurs. These studies and other studies on spinach suggest that more than one application of Provado will be necessary to adequately suppress aphid contamination in heads. The label suggests that applications be timed 5-7 apart. Our data tends to support this recommendation. Furthermore, timing applications should be based on days to harvest, level of aphid colonization and duration of aphid migration.