• Aphid Control in Broccoli

      Umeda, K.; Gal, G.; Murrieta, J.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      In a small plot field test, imidacloprid (Provado®), oxydemeton- methyl (Metasystox-R®), RH -7988 (Aphisttar®, Rohm and Haas), pirimicarb (Pirimor®), methamidaphos (Monitor®), and endosulfan were effective in significantly reducing the number of aphids in broccoli within 4 days of treatment (DAT). At 14 DAT, Provado, Metasystox-R, and Monitor continued to exhibit a significant reduction of aphids relative to the untreated check Pymetrozine (CGA- 215944, Novartis) at 0.022 lb AI/A did not effectively reduce aphids in this test.
    • Aphid Control in Spinach

      Umeda, K.; Gal, G.; Murrieta, J.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Several newly introduced insecticides that have potential for use in vegetable crops for aphid control were evaluated and demonstrated very good efficacy against green peach aphid (Myzus persicae). Field testing in spinach showed that CGA-293343 (Novartis) at the two rates tested significantly reduced the number of aphids relative to the untreated check. CGA-215944 (pymetrozine -Novartis) effectively reduced the number of aphids after two applications. Aphistar (RH- 7988 - Rohm and Haas) demonstrated the greatest reduction in the number of aphids per plant after each application. Provado (imidacloprid) and Thiodan (endosulfan) were applied as commercially available standard treatments and effectively reduced the number of aphids relative to the untreated check. Pirimor (pirimicarb) numerically reduced the number of aphids but was not significantly different relative to the untreated check.
    • Assessment of Fungicide Performance on Control of Downy Mildew of Broccoli in 1998

      Matheron, Michael E.; Porchas, Martin; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Peronospora parasitica is the pathogen responsible for causing downy mildew of broccoli, cabbage and cauliflower. Cool moist environmental conditions favor the development of downy mildew on these crops. Several potential new fungicides were evaluated for control of this disease on broccoli in 1998. The final severity of downy mildew in this trial was moderately high. Significant reduction in disease severity compared to nontreated plants was achieved by application of standard compounds such as Aliette, Bravo, maneb and Trilogy as well as the new fungicides Actigard, an Unknown, Curzate, Quadris, RH-7281, BAS 490, Acrobat and BAS 500. Broccoli yield was significantly increased compared to nontreated plots by treatments with Bravo, Curzate, Acrobat, BAS 500, Quadris, maneb, Actigard, BAS 490, an Unknown, RH-7281 and Aliette. The future registration and subsequent availability of one or more of these new chemistries for broccoli and related crops could help minimize the risk of development of resistance to fungicides used to manage downy mildew.
    • Cantaloupe Herbicide Weed Control Study

      Umeda, K.; Gal, G.; Strickland, B.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Clomazone (Command®), bensulide (Prefar®), sulfentrazone, and halosulfuron treatments applied preemergence (PREE) provided very good control of prostrate pigweed (Amaranthus blitoides), lambsquarters (Chenopodium album), and common purslane (Portulaca oleracea) at better than 90% at 5 weeks after treatment (WAT). Halosulfuron was effective in controlling all weeds better than 90% at 7 WAT Carfentrazone was not effective against most of the weeds present in the test but appeared to be safe on cantaloupe. Postemergence (POST) treatments alone did not provide acceptable control of pigweeds but controlled lambsquarters and common purslane at 2 WAT. Halosulfuron and bentazon (Basagran®) applied POST following PREE treatments controlled most of the weeds better than 90% through 7 WAT. Cantaloupe yields were highest with good weed control provided by PREE treatments followed by POST herbicide applications. Basagran at 0.50 lb /A injured cantaloupe after applications but yields were not affected compared to the untreated check. Command, sulfentrazone, and halosulfuron caused cantaloupe injury after PREE applications. Basagran caused substantial crop injury after POST 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.
    • Comparison of New Fungicides for Management of Powdery Mildew of Cantaloupe in 1997

      Matheron, Michael E.; Porchas, Martin; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Powdery mildew of cucurbits, which include cantaloupe, honeydew and watermelon as well as cucumbers and squash, occurs every year in Arizona. Moderate temperatures and relative humidity, succulent plant growth and reduced light intensity are factors that favor the development of powdery mildew, which is caused by the pathogenic fungus Sphaerotheca fuliginea Potential new fungicides were evaluated and compared to existing chemicals for control of powdery mildew of cantaloupe in a field trial conducted in the spring of 1997 at the Yuma Agricultural Center. The top performer in this study for disease control as well as reduction in culled fruit was a combination of Topsin-M + Trilogy. Other effective materials included BAS 490, Quadris, Procure, Benlate, Microthiol Special and Rally. Bayleton significantly reduced the amount of culled fruit, but did not significantly reduce the severity of powdery mildew. Compared to nontreated plots, a gain of up to $973 per acre could have been realized due to the reduction in amount of culled fruit in plots treated with fungicides. The potential availability of new chemistries for management of powdery mildew of cantaloupe and other cucurbits could help in the implementation of fungicide resistance management strategies, which strive to minimize the risk of resistance development by the pathogen to these compounds.
    • Diamondback Moth Control in Spring Cabbage

      Umeda, K.; Gal, G.; Murrieta, J.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      In a small plot field study, diamondback moth (Plutella xylostella, DBM) in cabbage were not significantly reduced by various insecticide treatments when applied one time during the season. ABG -6406 (Abbott Laboratories), Success® (spinosad, DowElanco), and Kryocide® generally maintained larger -sized DBM larval numbers below or similar to the untreated check at most rating dates. Cabbage treated by Xentari®, Alert® (clorfenapyr, Cyanamid), Confirm® (tebufenozide, Rohm and Haas) and Proclaim® (emamectin benzoate, Novartis) exhibited numbers of larger -sized larvae that exceeded the untreated check at certain rating dates. DBM populations were not consistent during the testing period to allow assessment of treatment differences.
    • Efficacy of Pyrethroid Insecticides for Cabbage Looper Control in Head Lettuce, 1997

      Kerns, David L.; Tellez, Tony; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Mustang 1.5EW, Ammo 2.5EC, Pounce 3,2EC, Scout X-TRA, and three formulations of Karate were compared for efficacy to cabbage loopers infesting head lettuce in Yuma, AZ Karate and Pounce provided the most consistent cabbage looper control followed by Mustang and Scout X-TRA. Ammo appeared slightly inferior to the other pyrethroids tested. There did not appear to be any obvious differences in the efficacy of the three Karate formulations.
    • 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.
    • Evaluation of New Fungicides for Management of Downy and Powdery Mildew of Lettuce in 1998

      Matheron, Michael E.; Porchas, Martin; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Bremia lactucae and Erysiphe cichoracearum, respectively, cause downy and powdery mildew of lettuce. Cool moist environmental conditions favor the development of downy mildew, whereas warm and dry weather is conducive for powdery mildew. Several potential new fungicides were evaluated for control of these diseases of lettuce in 1998. The final severity of downy mildew in this trial was low. In addition to the standard compounds maneb, Aliette and Trilogy, several fungicides currently in development significantly reduced the severity of downy mildew compared to nontreated plants. These chemistries included Acrobat, RH -7281, an Unknown, Actigard, EF1295, Curzate, Quadris, BAS 500, QST 153, BAS 505 and BAS 490. Untreated lettuce plants were heavily infected with powdery mildew. In addition to the standard materials Microthiol Special and Trilogy, powdery mildew was significantly reduced on plants treated with BAS 490, BAS 505, EF1295, BAS 500 and Quadris. The possible availability of one or more of these chemistries under development for lettuce could help in efforts to develop and maintain a fungicide resistance management program for plant medicines of importance for this crop.
    • Evaluation of Preemergence Herbicides for Onion Weed Control

      Umeda, K.; Gal, G.; Strickland, B.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      At three test sites, ethofumesate (Nortron®) at 1.0 and 2.0 lb AI /A was safe on onions. Nortron appeared to provide marginal control of light to moderate weed infestations of London rocket (Sisymbrium irio) at two sites. Pendimethalin (Prowl®) at 0.50 and 0.75 lb Al/A was safe on onions at two sites with furrow irrigation. At three sites with sprinkler irrigation, Prowl treatments caused as high as 62 to 88% stand reduction when sprinklers were used to incorporate the herbicide. Bensulide (Prefar0) injured onions at early rating dates and height measurements indicated that the plants were shortened relative to the untreated check. End of the season visual observations showed that onions had grown out of the initial injury and the crop did not appear to be damaged. Prefar combined with Prowl or Nortron was more injurious to onions with sprinkler irrigation than with furrow irrigated incorporation. Prefar gave marginal weed control in the tests under conditions with low weed infestations. Lactofen (Cobra®) was injurious to onions at all five test sites and caused significant crop stand reduction. Combination treatments of Prowl with DCPA (Dacthal®) or Prefar were damaging to onions under sprinklers but injury was minimal with furrow irrigations. Metolachlor (Dual®) and dimethenamid (Frontier®) caused minimal injury and no stand reduction of onions under sprinklers but with furrow irrigation, the stand was reduced and height reduction was substantial. The series of field tests demonstrated that herbicide performance was significantly influenced by irrigation practices. Prowl herbicide was extremely injurious and caused substantial crop stand reduction with sprinkler irrigation. Dual and Frontier exhibited less injury on onions under sprinklers than with furrow irrigation. Cobra at 0.25 lb AI /A was damaging to onions regardless of irrigation practice.
    • Insecticides for Whitefly Control in Cantaloupe

      Umeda, K.; Gal, G.; Strickland, B.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      In small plot field testing, the new IGR's, buprofezine, pyriproxyfen, and fenoxycarb plus CGA-215944 , offered very good reduction of the WF adults and immature stages for several weeks. Combinations of the new insecticides and alternating weekly applications were effective in minimizing WF season-long. Pyrethroids, bifenthrin and esfenvalerate plus endosulfan treatments, were effective after early applications and nymph counts were elevated after the third application. Oxydemeton-methyl and imidacloprid treatments applied weekly compared favorably with the new chemistries to reduce adults and immatures. Pyridaben applied weekly reduced adult counts relative to the untreated check but immatures increased after the third application.
    • Leafminer Control in Cantaloupe

      Umeda, K.; Gal, G.; Strickland, B.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      In a small plot field test on cantaloupes, abamectin (Agri-mek®), cyromazine (Trigard®), spinosad (Success®), and pyriproxyfen (Knack®) demonstrated efficacy to reduce the number of mined leaves caused by leafminers (Liriomvza sativae and L. trifolii). Multiple applications of Agri-mek and Trigard resulted in melons having the fewest number of mined leaves. Success and Knack were effective in reducing the number of mined leaves relative to the untreated check. All of the treatments provided effective control of leafminers for 14 to 21 days after treatment. Success exhibited a rate response with the highest rate showing the fewest number of mined leaves compared to the lower rate.
    • 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.
    • Mating Disruption of Beet Armyworm in Vegetables by Synthetic Pheromone

      Kerns, David L.; Tellez, Tony; Nigh, Jeff; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      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 ineffective at reducing beet armyworm populations the under high population pressure. Under low beet armyworm pressure, pheromone dispenser did significantly reduce beet armyworm populations, but not to the point where insecticide applications could be eliminated.
    • New Fungicides Evaluated for Control of Sclerotinia Leaf Drop of Lettuce in 1997 and 1998

      Matheron, Michael E.; Porchas, Martin; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Sclerotinia leaf drop of lettuce is caused by two different species of this fungal pathogen, Sclerotinia minor and S. sclerotiorum. Cool and moist environmental conditions favor this disease. Some new fungicides in development were evaluated for control of leaf drop on lettuce during the winter vegetable growing seasons of 1996-97 and 1997-98. Sclerotia of each pathogen were applied to plots after thinning and just before the first of two applications of test compounds. The final severity of leaf drop in these trials was high. Significant reduction in disease or increase in marketable heads compared to nontreated plants was usually achieved by application of the standard compounds Ronilan and Rovral as well as the new fungicides BAS 500 and an "unidentified" material. The future registration and subsequent availability of one or both of these new chemistries for lettuce could provide equivalent disease control to that of the current standard materials with 0.2 to 0.25 lb active ingredient (a.i.) per acre instead of the current 1.0 lb a.i. per acre required with the standard compounds.
    • 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.
    • Noncrop Herbicide Weed Control

      Umeda, K.; Gal, G.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Paraquat and diquat were effective against weeds immediately at 3 DAT. Glyphosate, sulfosate, and glufosinate exhibited activity against the weeds at 7 to 10 DAT. Paraquat provided the most complete weed control of most weeds at 10 to 16 DAT. Most of the diquat treated weed recovered and exhibited regrowth after 22 DAT. Glufosinate did not provide adequate control of most weeds at 22 DAT similar to diquat. Glyphosate and sulfosate were nearly equivalent at 0.50 and 2.0 lb AI/A against most weeds at most of the rating dates.
    • 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.