• Postemergence Herbicide Weed Control in Cole Crops Study

      Umeda, K.; Gal, G.; Murrieta, J.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Weed control ratings at 3 weeks after treatment (WAT) showed that knotweed (Polvgonum argyrocoleon) and yellow sweetclover (Melilotus officinalis) were not controlled by oxyfluorfen (Goal®), pyridate (Lentagran®), clopyralid (Stinger®), sulfentrazone (FMC), or carfentrazone (FMC). Carfentrazone at 0.50 lb AI/A gave good control ( >89 %) of London rocket (Sisvmbrium irio) and sowthistle (Sonchus oleraceus). A lower rate at 0.125 lb AI/A provided acceptable control (85 %). Carfentrazone at 0.50 lb AUA caused severe broccoli and cabbage injury and crop stand reduction. Sulfentrazone at 0.50 lb AI/A gave nearly acceptable control of knotweed, London rocket, and sowthistle. Cabbage was severely injured and broccoli appeared to be more tolerant and injury was marginally acceptable (15 %). Stinger and Goal gave nearly acceptable control of sowthistle. Goal at 0.094 lb AI/A gave 80% control of London rocket. Goal caused marginally acceptable injury (12 to 17 %) and Stinger caused minimal crop injury. Goal appears to be ineffective against weeds at less than 0.094 lb AI/A and crop safety is very marginal. Lentagran was relatively safe on broccoli and cabbage but did not control the existing weed spectrum.
    • Evaluation of Insect Growth Regulators for Management of Whiteflies in Melons

      Palumbo, John C.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Whitefly populations were assessed under different IGR exposure levels, and compared to Admire. When used alone during the season Applaud, Knack, and Sterling significantly reduced immature colonization similar to the standard Admire application and significantly greater than the untreated melons. Applaud treatments, regardless of spray frequency, showed the most consistent reduction in immature whiteflies. Applaud through its vapor activity also appeared to provide a long residual period of control against nymphs. Single applications of Knack and Sterling were considerably less effective in preventing colonization than applying these material twice during the season. These compounds appeared to have considerably less residual activity, which is consistent with their modes of activity. All of the IGRs had a significant impact on the distribution of nymphs among the leaves on the primary vine. In addition, Applaud provided the best melon quality. We now have a good understanding of how the IGRs influence whitefly population growth, the residual mortality of the IGRs and proper application timing for whitefly management. This information will allow us to develop a simple and reliable method that growers and PCAs can use to assess product performance and time spray applications.
    • Commercial Field Performance of Confirm and Success on Head Lettuce and Broccoli

      Palumbo, John C.; Hannan, Todd A.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Field trials were conducted in the Yuma and Gila Valleys to assess the commercial field performance of Confirm and Success insecticides against beet armyworm and cabbage looper larvae. Ten lettuce and five broccoli fields were treated with combinations of Confirm, Success, and standard insecticides on various stages of plant growth. Success provided quick knockdown of larvae, but ultimately Confirm provided equitable control. Cabbage looper control with Confirm appeared to be influence by application volume and plant size. Addition of pyrethroid to Confirm did not provide additional efficacy. Success provided good suppression of leafminer adults and thrips. Both products provided control equal to conventional standards and will become valuable components of future lettuce pest management programs in Arizona.
    • Comparison of Alternative Management Approaches for Lepidopterous Larvae in Fall Lettuce

      Palumbo, John; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      For the second year, 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.
    • Management of Aphids and Thrips on Leafy Vegetables

      Palumbo, John; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Research has been conducted at the Yuma Agricultural Center for the past 5 years to gain an understanding of aphid and thrip population dynamics in spring lettuce, spinach and Cole crops. This information coupled with insecticide efficacy studies has allowed us to formulate recommendations for managing these serious pests of leafy vegetables. Provided below is information on species composition, sampling and chemical control of aphids and thrips. This paper should provide guidelines for pest control advisors and growers in making management decisions.
    • New Insecticide Alternatives 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), 1999-02)
      Several new insecticide was compared to Admire and Provado combinations for management of aphids in head lettuce in Yuma in two trials conducted in 1998. Foliar applications of Provado, Fulllfill, Aphistar and Acetamiprid appear to provide an alternative method of controlling aphids on lettuce comparable to prophylactic applications of Admire. In addition, at planting and side dress soil applications of thimethoxam provided aphid control comparable to Admire. The prevention of aphid colonization in lettuce heads with the foliar alternatives may depend greatly on the timing and frequency of applications before harvest occurs. Residual activity of the new foliar alternatives ranged from at least 7-14 days. These studies suggest that more than one application of the foliar products will be necessary to adequately suppress aphid contamination in heads. Evaluations of thiamethoxam suggest that it is more mobile in the soil than Admire and may be a candidate for side dress applications for aphid management.