• Alternative IPM Programs for Management of Lepidopterous Larvae in Fall Lettuce

      Palumbo, John; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      For a third year, a large block experiment was conducted at the Yuma Ag Center to compare the field performance of several lettuce IPM programs for control of lepidopterous larvae. Conventional, Reduced -risk , Bio-based and Modified IPM spray regimes were applied to control beet armyworm, cabbage looper and Heliothis species throughout the fall growing season. Differences in populations of total larvae among the treatments, relative to insecticide treatments and timing of application were observed at various times during the season. In general, the Conventional, Reduced -risk and Modified IPM approaches 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 a strong data base to support the need for the development of experimental and biorational insecticide products as alternatives to conventional management programs in desert lettuce production. In addition, it demonstrates the dependance of IPM programs on a broad range of plant protection chemicals and control tactics.
    • Aphid Control in Cabbage Study

      Umeda, K.; MacNeil, D.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Aphistar provided the quickest reduction of the aphids after one application and continued residual control for up to 14 DAT-2. Following a second application and reduction of aphids, Pirimor, Provado, Fulfill, Actara, and Metasystox-R provided a varied degree of residual control of aphids between 5 and 14 DAT-2. A comparison of Fulfill rates indicated that the two rates were equally effective at 5 DAT-2 but the lower rate did not offer as long residual control compared to the higher rate. Endosulfan was moderately effective and did not provide acceptable control after 1 week.
    • Baseline Susceptibility of Cabbage Looper to Insecticides

      Kerns, David L.; Tellez, Tony; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Populations of cabbage looper were collected during 1998 from 12 geographical location in the United States, and were assessed for susceptibility to six new insecticides: Alert, Avaunt, Confirm, Intrepid, Proclaim, and Success, and to a standard insecticide, Pounce. There was no detectable evidence indicating insecticide resistance to any of the new insecticides. However, variability in response to Confirm, Proclaim, and Success warrants close resistance monitoring. Cabbage looper response to Pounce was extremely variable, and there was strong evidence for the occurrence of resistance. Populations from Jackson, MS, Sunderland, MA, and Whately, MA all exhibited high levels of resistance to Pounce with resistance ratios of 90.60, 93.50, and 76.30-fold respectively.
    • Comparative Effect of Five Fungicides on the Development of Root and Stem Rot and Survival of Chile Pepper Plants Grown in Field Soil Naturally Infested with Phytophthora capsici

      Matheron, Michael E.; Porchas, Martin; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Five different fungicides, including azoxystrobin, dimethomorph, fluazinam, fosetyl-Al, and mefenozem (metalaxyl), were evaluated for their ability to inhibit the development of root and crown rot and increase the survival of chile pepper plants grown in soil naturally infested with Phytophthora capsici. For chile pepper plants grown in field soil naturally infested with P. capsici and subjected to a 48 h flood period every 2 weeks, growth and survival of plants receiving one treatment of dimethomorph at 100 μg/ml or fluazinam at 1,000 μg/ml were significantly greater than that for plants treated once with azoxystrobin at 1,000 μg/ml or fosetyl-Al at 3,000 μg/ml. For each tested fungicide, values for duration of plant survival and shoot and root fresh weight usually were numerically larger but not significantly different for chile peppers receiving water as needed compared to those flooded for 48 h every 2 weeks. The potential and relative value of azoxystrobin, dimethomorph, fosetyl-Al, and fluazinam as chemical management tools for Phytophthora root and stem rot on chile pepper, in addition to mefenozem (metalaxyl), has been demonstrated.
    • Comparison of Neonicotinoid Use Patterns for Silverleaf Whitefly Management in Melons and Broccoli

      Palumbo, John C.; Muliis, Clay Jr.; Reyes, Francisco; Amaya, Andreas; Lesdesma, Luis; Cary, Lisa; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Studies were conducted in 1998 and 1999 to evaluate three neonicotinoid insecticides for control of silverleaf whiteflies in melons and broccoli plots at the Yuma Agricultural Center. The results of these studies demonstrate that these insecticide uses offer vegetable growers management alternatives for controlling whiteflies comparable to what they have experienced with Admire®. In our spring trials, we applied Platinum® at planting, as a split application, and as a sidedress application. All methods provided whitefly efficacy similar to that provided by Admire. However, the split and sidedress applications provided more consistent residual control than Platinum applied at planting. Because of the mobility of the product in the soil, growers may have more flexibility for effectively applying the material post-planting. In addition, Assail, was applied as a foliar spray at various densities. Under spring growing conditions, applications of Assail provided significant whitefly control when initiated at low densities. Under high whitefly densities on fall melons and broccoli, application of Assail was capable of significantly reducing existing immature populations. These evaluations suggests that Platinum and Assail may be promising alternatives to Admire. We presume that it may allow growers to use the product in a responsive manner as a side dress (Platinum) or as a foliar (Assail) rather than having to rely on prophylactic Admire applications at planting.
    • Comparison of New Fungicides to Manage Sclerotinia Leaf Drop of Lettuce in 2000

      Matheron, Michael E.; Porchas, Martin; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Sclerotinia minor and S. sclerotiorum are the two soil-borne pathogenic fungi that cause Sclerotinia leaf drop in Arizona. Moist soils and moderate temperature favor this disease. Some new fungicides in development were evaluated for control of leaf drop on lettuce during the winter vegetable growing season of 1999-2000. Sclerotia of each pathogen were applied to plots after thinning and just before the first of two applications of test compounds. In this trial, the final count of dead lettuce plants usually was numerically reduced, compared to nontreated plots, in plots infested with either pathogen that were treated with the standard compounds Ronilan or Rovral as well as the experimental compound Medallion; however, the reduction was significant only in plots infested with Sclerotinia sclerotiorum. The number of dead plants in plots infested with either Sclerotinia minor or S. sclerotiorum was significantly reduced by another experimental chemistry, Fluazinam. Finally, a biological control product, Serenade, significantly reduced disease in plots containing S. minor, but not S. sclerotiorum. Continued demonstration of efficacy by Serenade may provide the opportunity to utilize a biological control product to reduce the incidence of Sclerotinia leaf drop of lettuce caused by S. minor.
    • Effect of Cultivar and Actigard on Development of Powdery Mildew on Lettuce

      Matheron, Michael E.; Porchas, Martin; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Nine different cultivars of lettuce were planted at the Yuma Valley Agricultural Center. Plants were treated four times with two different rates of Actigard. Control plants were not treated. Near plant maturity (Mar. 23, 2000) the severity of powdery mildew was recorded. Among nontreated plants, Cibola, Conquistador, and Coolguard had the lowest levels of powdery mildew. On the other hand, Bos 9003 and Mohawk had significantly higher levels of powdery mildew than all other tested cultivars. Four applications of Actigard at a rate of 14 g. of active ingredient per acre significantly reduced the level of powdery mildew on all nine tested cultivars of lettuce. On two lettuce cultivars, powdery mildew was significantly lower when treated with Actigard at the 28 g. a.i./A rate when compared to the 14 g. a.i./A rate. No evidence of phytotoxicity was apparent on plants treated with Actigard. This study suggests that lettuce cultivars differ in susceptibility to powdery mildew. Also, Actigard was able to provide added protection against powdery mildew for all tested lettuce cultivars.
    • Effect of Preplant Fumigation on Yield of Chile Pepper Infected with Root-Knot Nematode

      Olsen, M.; McClure, M.; Husman, S.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      A field test was established in 1999 to determine the effect of preplant soil fumigation on yield of chile pepper in southeastern Arizona in order to give growers data on which to base management decisions. Replicated plots within a nematode-infested field planted with New Mex 6-4 chile in March 1999 were either treated with Telone II fumigant at 7 gal/A two weeks before planting or not treated. In a mid-season assay in July 1999, the effects of fumigation were evident in plant canopy growth although numbers of J2/cc soil were not significant between treatments (p=0.058). Differences in yields between fumigated plots and untreated plots were significant (p=0.014). The average yield in fumigated plots was 12.4% higher than that in untreated plots.
    • Evaluation of Foliar Insecticides for Whitefly Control in Cantaloupes

      Umeda, K.; MacNeil, D.; Roberts, D.; Lund, N.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      The pyrethroid insecticides esfenvalerate (Asana®), bifenthrin (Capture®), or fenpropathrin (Danitol®) combined with endosulfan effectively reduced whitefly (WF, Bemisia argentifolii) counts at 1 week after treatment (WAT) following each of five applications. Asana, Capture, or Danitol combined with endosulfan effectively reduced WF counts at 1 WAT following each of five applications. Danitol treated melons exhibited fewer adult WF compared to Asana or Capture at most of the rating dates at 6 days after treatment (DAT) of each of the applications and also at 11 DAT of the last application. A single application of buprofezin (Applaud®) treatments or pymetrozine (Fulfill®) effectively reduced WF nymphs for 18 to 24 DAT and adults were reduced for 18 DAT. Fulfill exhibited a rate response where the higher rate reduced WF counts more than the lower rate.
    • Evaluation of Fungicide Performance for Control of Powdery Mildew on Lettuce in 2000

      Matheron, Michael E.; Porchas, Martin; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Powdery mildew on lettuce is caused by the fungus Erysiphe cichoracearum. This disease is favored by moderate to warm temperatures and dry weather conditions. Several potential new fungicides were evaluated for control of powdery mildew on lettuce in 2000. Powdery mildew appeared in our plots by Feb 9 and reached high levels by plant maturity on Mar 2. Nontreated lettuce plants were heavily infected with powdery mildew at plant maturity, whereas the disease ranged from low to virtually nonexistent levels in plots treated with BAS 500, Quadris+Actigard, Flint, Flint+Actigard, Flint alternated (alt.) with Trilogy, Rally, Microthiol, EksPunge alt. with Microthiol, KHHUBF-99-001, Quinoxyfen, Flint alt.with Serenade, Rally alt. with Serenade, and Serenade alt. with Microthiol. These compounds have various modes of action, and some could be available for “organic” production. The future availability of one or more of these chemistries under development could help in efforts to control powdery mildew of lettuce and to establish and maintain a fungicide resistance management program for plant disease control products of importance for this crop.
    • Evaluation of Herbicides for Nutsedge Control in Carrots

      Umeda, Kai; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Halosulfuron and sulfentrazone were not safe to carrots at the lowest rates tested at 0.025 and 0.188 lb AI/A, respectively. At 20 DAT, halosulfuron at 0.038 to 0.075 lb AI/A gave better than 92% control of nutsedge in carrots. Nutsedge control was 77 to 80% at 20 DAT sulfentrazone applied at 0.188 to 0.375 lb AI/A. Both herbicides demonstrated slow activity against nutsedge during the first 7 DAT and then progressed to reduce weed growth at 13 to 20 DAT. Sulfentrazone appeared to act slightly faster than halosulfuron but showed maximum activity at 13 to 20 DAT.
    • Fall Planted, Late Maturing Onion Variety Trial

      Clark, L. J.; Walser, R.; Carpenter, E. W.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Thirteen late maturing onion varieties were planted in the fall of 1998 and grown in a replicated small plot trial on the Safford Agricultural Center. Bulbs were pulled and the tops removed in early June. Three NuMex varieties, Mesa, Starlite and BR1, produced the best yields. Yields are shown in tabular form together with size distribution and quality characteristics.
    • Field Evaluation of Broccoli Varieties Grown in Southwest Low Desert Soils

      Zerkoune, Mohammed A.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Based on acreage, broccoli is the third largest vegetable crop in Yuma County, after head lettuce, and romaine. It generates over $36 000000 a year. Efforts are continuously made by both seed industry and growers to grow better varieties that respond to consumers’ choice. Selection of newly adapted varieties is made based on agronomic performance as well as commercial value. Stand uniformity, disease resistance, color, head shape, and head size are among characteristics that are evaluated. The objective of this demonstration trial is to evaluate the characteristics of new varieties grown under standard cultural practices. Twelve varieties were tested at Yuma Agricultural Research Center. No incidence of disease was observed and the overall evaluation rating was greater than 4 indicating that all varieties tested will do well under similar growing conditions and planting date. Significant head diameter and plant height were observed among varieties tested.
    • Field Evaluation of Cauliflower Varieties Grown in Southwest Low Desert Soils

      Zerkoune, Mohammed A.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Selection of adapted varieties to environmental factors and soil types are paramount to growing profitable cauliflower crops. Varieties are selected for uniform maturity, field holding capability, head size, shape and color. The objective of this demonstration trial is to evaluate new and existing commercial varieties under standard field conditions. Seven varieties were planted in a single row and evaluated at Yuma Agricultural Research Center (YAC) for their agronomic characteristics and their commercial values. All varieties tested performed well with an overall rating of 4 or better, indicating that when planted under similar conditions and planting dates, these varieties are expected to do well. However a significant head weight and head diameter difference was observed among varieties tested.
    • Field Evaluation of Crisp-head Lettuce Varieties Grown in Southwest Low Desert Soils

      Zerkoune, Mohammed A.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Crisp-head lettuce plays an important role in Yuma’s economy. An estimated 51000 acres are cropped to large number of varieties each year with planting season that spreads from late August to March. Three demonstration sites and three planting dates were selected to compare new and existing varieties of head lettuce on growers’ fields using standard farming practices. Selected growth parameters were evaluated throughout the growing season. Results indicate that varieties tested at JV Farms in Welton and at Yuma Agricultural Center (YAC) are expected to do well if grown under similar conditions and planting time. Some varieties tested during the second planting slot on Doug Melon Farm experienced some incidence of diseases. All three planting sites showed a significant head weight difference and two out of three planting sites showed a significant head diameter difference.
    • Halosulfuron for Weed Control in Watermelon

      Umeda, K.; MacNeil, D.; Roberts, D.; Lund, N.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Halosulfuron at rates ranging from 0.05 to 0.10 lb AI/A with no adjuvant added to the POST application spray did not cause any injury to watermelons. Halosulfuron did not appear to cause significant crop injury earlier in the season to reduce marketable fruit yield at harvest. Halosulfuron was highly effective against London rocket but did not control purslane or groundcherry. Weed control efficacy was improved significantly when Latron CS-7 or Activator-90 was added to halosulfuron at either 0.05 or 0.075 lb AI/A. LI-700 did not improve the activity of halosulfuron over the treatments without an adjuvant.
    • Herbicide Screen for Melons

      Umeda, K.; MacNeil, D.; Lund, N.; Roberts, D.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Seventeen herbicides recently gaining registrations in corn, soybeans, or other major crops were evaluated in screening tests for potential use in melons. In a preemergence herbicide screening test, flumioxazin, dimethenamid, halosulfuron, and s-metolachlor demonstrated melon crop safety at rates higher than rates for effective weed control. In a postemergence screening test, halosulfuron and rimsulfuron gave acceptable weed control with adequate crop safety. Flumetsulam and thifensulfuron appeared to offer some acceptable weed control with a very narrow margin of crop safety. Herbicides that did not offer adequate melon crop safety or acceptable weed control in the screening tests were carfentrazone, sulfentrazone, cloransulam, flumiclorac, fluthiamide/metribuzin, imazamox, isoxaflutole, triflusulfuron, primisulfuron/prosulfuron, and clomazone.
    • Impact and Management of Western Flower Thrips on Romaine Lettuce

      Palumbo, John; Mullis, Clayton Jr.; Reyes, Francisco; Amaya, Andreas; Ledesma, Luis; Cary, Lisa; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      A season-long study was conducted to evaluate the efficacy of several conventional, experimental and bio-based insecticide combinations used in rotation against western flower thrips (WFT) in romaine lettuce. Results from this study showed that several insecticide rotational programs provided good control of WFT populations throughout the season. Adult abundance peaked just prior to the fourth spray on 28 March, whereas larvae numbers peaked about 2 weeks earlier on March 13. Fluctuations of larval and adult populations observed from weekly samples suggests that greater than 3 WFT generations developed during the experimental period. Averaged across all sample dates, the Success, Lannate and Warrior based rotations maintained adult and larval populations at significantly lower levels than all other treatments. The Bio-based, organic rotations (Neem/Garlic/COC/Sulfur/Diatect) did not differ from the untreated check. Percentage reduction of WFT larvae and adults compared with the untreated control was significantly greater following sprays which contained Success combinations. Consistent with reduction in WFT numbers, the Success/Lannate/Warrior, and Dimethoate based rotations resulted in significantly greater yields and less damage. Regression analysis suggests that larvae and total thrips abundance more consistently describes the variation measured in plant weights. Overall, this preliminary data further indicates that maintaining WFT abundance at low levels is important for maintaining romaine yield and quality.
    • Lettuce Variety Trial

      Clark, L. J.; Walser, R.; Carpenter, E. W.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Eleven head lettuce varieties and four leaf lettuce varieties were grown in a replicated small plot trial on the Safford Agricultural Center in 1998. Desertgreen variety of head lettuce from Harris Moran produced a crop with the best head weight, size and firmness rating. Premiere variety followed closely behind. Of the leaf lettuce varieties tested, Saguaro Romaine produced the best quality and quantity product. Per acre yields are calculated for each variety in the study.
    • Management of Western Flower Thrips in Head Lettuce with Conventional and Botanical Insecticides

      Palumbo, John; Mullis, Clayton Jr.; Reyes, Francisco; Amaya, Andreas; Ledesma, Luis; Cary, Lisa; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 2000-08)
      Studies were conducted in three independent field trials to evaluate the efficacy of conventional and botanical insecticides against western flower thrips in head lettuce. Trials were conducted in spring lettuce under moderate and heavy populations pressures. Actara and Avaunt, two new experiential insecticides did not significantly control adults and provided only marginal activity against the larvae when applied alone. Combination of these products with either Lannate or Warrior significantly enhanced control, but usually not greater than that shown from the Lannate or Warrior applied alone. Several botanical products were evaluated (azadirachtin, pyrethrins, crop oils and garlic). Unfortunately, none of the botanical products significantly reduced thrips numbers to economically acceptable levels of control. Similar to previous studies, our results suggest that even the most efficacious products appeared to maintain thrips populations at constant levels and not necessarily reducing their numbers. More research needs to be conducted to determine the proper timing of applications to achieve optimal thrips using both conventional and botanical insecticides.