• 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.
    • 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.
    • Relative Susceptibility of Red and Green Color Forms of Green Peach Aphid to Insecticides

      Kerns, D. L.; Palumbo, J. C.; Byrne, D. N.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Field populations of green peach aphid, Myzus persicae (Sulzer), were collected from five produce fields near Yuma, Arizona. Three of the fields sampled contained both red and green-colored forms, while the remaining two fields contained only green-colored green peach aphids. Red-colored aphids were consistently more resistant to dimethoate and lambda-cyhalothrin, and usually more resistant to endosulfan than green-colored aphids collected from the same field. Slight differences in susceptibility to imidacloprid suggest that development of resistance is a possibility and justifies close resistance monitoring. Susceptibility to imidacloprid was not influenced by color form. We detected little or no differences in susceptibility to acephate, mevinphos or bifenthrin.
    • Tank Mixing New Insecticide Chemistries with a Pyrethroid Insecticide for Control of Lepidopterous Pests in Head Lettuce, 1997

      Kerns, David L.; Tellez, Tony; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      Confirm, Success and Proclaim were evaluated for lepidopterous insect control in lettuce with and without the addition of Mustang 1.5EW. Success and Proclaim used alone were highly efficacious toward cabbage looper and Heliothinae and did not appear to benefit greatly from the addition of Mustang. However, Confirm's activity towards Heliothinae was significantly improved by the addition of Mustang. Additionally, on large framed plants where coverage is difficult, Confirm benefitted from the addition of a pyrethroid for control of loopers.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • Preemergence Herbicide Combinations for Onion Weed Control Study

      Umeda, K.; Gal, G.; Strickland, B.; Oebker, Norman F. (College of Agriculture, University of Arizona (Tucson, AZ), 1999-02)
      DCPA (Dacthal®) at 9.0 lb AI /A, the commercial standard herbicide, slightly reduced the number of plants and shortened the plant height compared to the untreated check. Preemergence (PREE) herbicide treatments that caused injury as height reduction similar to Dacthal included pendimethalin (Prowl®), propachlor (Ramrod®), metolachlor (Dual®), dimethenamid (Frontier®), ethofumesate (Nortron®), and benefin (Balan®). Visual observations did not indicate significant stand reduction or crop injury compared to plant counts. Treatments that caused minimal visible crop injury (<10 %) were Ramrod, Balan and lower rates of Frontier and Nortron. Moderate to acceptable injury (15 %) was observed on onions treated by Prowl, Dual, Frontier, and Nortron. Treatments that significantly reduced crop stand were Prefar at 6.0 lb AI /A, lactofen (Cobra®), thiazopyr (Visor®), and some combinations of the three herbicides. Combination treatments that caused marginally acceptable injury included Prowl plus Dual, Nortron plus Prowl, Prefar plus Nortron, Nortron plus Frontier, Ramrod plus Frontier, Ramrod plus Nortron, and Ramrod plus Balan. Early weed control ratings showed that Prowl at 0.5 and 0.75 lb Al/A, Nortron, Cobra, Visor applied alone gave acceptable control (>85 %) of London rocket (Sisvmbrium irio), sowthistle (Sonchus oleraceus), and sweetclover (Melilotus officinalis). Prowl at 0.75 lb AI/A and Cobra gave season -long control of all weeds. Early weed control ratings of combination herbicide treatments demonstrated that Prowl or Nortron combined with other herbicides gave acceptable weed control. Prowl at 0.50 lb AI /A plus Ramrod, Nortron, or Dual at the lower rates slightly improved weed control compared to each of the herbicides applied alone.
    • 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.
    • 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.