• Defoliant Effect on Melons

      Umeda, Kai; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Sodium chlorate exhibited the fastest developing crop phytotoxicity symptoms within 3 days after treatment (DAT). Within three days of application, significant crop injury at 40 and 80% was observed on cantaloupes for sodium chlorate applied at 1.0 and 4.0 lb AI/A, respectively. Thidiazuron/diuron (Ginstar7) caused injury that was slightly slower to develop and the crop declined severely during the next 10 days. Ginstar at 8.0 or 12.0 oz product/A initially caused 20% crop injury. Thidiazuron (Dropp7) caused the least injury on cantaloupes and injury reached unacceptable levels at 1 WAT. Dropp at 0.1 and 0.4 lb AI/A initially showed less than 10% crop injury. Dropp at the rates tested caused minimal defoliation.
    • Leafminer Control in Cantaloupes

      Umeda, Kai; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Cantaloupe leaf damage from leafminer activity was minimal to non-existent when evaluated at 6 days after treatment (DAT) following each of the first four weekly application dates. At 13 DAT-4, the number of mined leaves increased tremendously over the previous observation date. The untreated cantaloupes showed an increase from 30.8 to 81.8 mined leaves compared to the previous week. Agri-mek and the alternation treatment of Trigard, Success7, and Agri-mek applied on cantaloupes showed the fewest number of mined leaves at about 22 mined leaves. Trigard and Success treated cantaloupes had increased number of mined leaves ranging from 44 to 56.8. Agri-mek and the alternation treatment consistently had the fewest number of mined leaves during the course of the test period. Trigard and Success treatments performed similarly and reduced the number of mined leaves relative to the untreated cantaloupes. Success at the higher rate appeared to be slightly more active by showing numerically fewer mined leaves than the lower rate of application. Success treated melons yielded nearly twice as much compared to the other treatments and the untreated. Success treated melons also offered a higher number of marketable fruit at better than 80% compared to about 60% for the other treatments. Less stickiness was observed on the Success treated cantaloupes. There appeared to be an effect from Success applications on whitefly to reduce the honeydew stickiness.
    • Comparison of New Fungicides for Management of Downy Mildew of Broccoli in 1999

      Matheron, Michael E.; Porchas, Martin; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Downy mildew of broccoli, cauliflower and cabbage is caused by the fungus Peronospora parasitica. 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 1999. 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, Ridomil Gold+maneb, maneb and Trilogy as well as nonregistered chemistries including Acrobat, Actigard, Curzate, Flint, Quadris, Serenade, Sovran, BAS 500, DPX-KP481 and RH-7281. The future registration and subsequent availability of one or more of these new chemistries for broccoli and related crops could enhance the overall level of disease control as well as help minimize the risk of development of resistance to fungicides used to manage downy mildew.
    • Evaluation of Herbicides for Cantaloupe Weed Control

      Umeda, Kai; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      At 4 weeks after treatment (WAT), all preemergence (PREE) treatments were completely safe on cantaloupes. At 1 WAT of postemergence (POST) applications, marginally acceptable melon injury (11 to 19%) was observed. At 6 WAT, crop injury increased significantly for both halosulfuron and bentazon. Halosulfuron (POST) following bensulide (PREE) caused minimal crop injury. The pigweeds were marginally controlled when POST treatments followed PREE herbicides. Tumble pigweed (Amaranthus albus) was more difficult to control than prostrate pigweed (A. blitoides). Halosulfuron gave good control of nutsedge (Cyperus rotundus) at 6 WAT.
    • Timing of Postemergence Herbicides for Onion Weed Control

      Umeda, K.; Gal, G.; Strickland, B.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Bromoxynil (Buctril®) at 0.063, 0.094, and 0.125 lb AI/A was completely safe on onions treated at the early first true leaf stage of growth. Onions did not exhibit visual injury at 12 days after treatment (DAT) and height was not different from the untreated at 45 DAT. Melilotus officinalis (yellow sweetclover) was only marginally controlled by both Buctril and oxyfluorfen (Goal®). Goal provided better weed control with an earlier application timing at 0.063 lb AI/A than the later application at 0.25 lb AI/A. All herbicide treated onions yielded higher than the untreated. A rate response was observed for Buctril and Goal where onion yields were higher for the higher rates of application. Results indicate that the POST herbicides at lower than typical use rates were safe when applied to onions at an early timing. Effective weed control of some weeds was observed but yellow sweetclover was not adequately controlled.
    • Development and Consumption Rates for Lepidopterous Larve as Influenced by Host-Plant and Temperature

      Palumbo, J. C.; Reyes, F.; Amaya, A.; Ledesma, L.; Cary, L.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Several laboratory studies were conducted to examine the relationships between larval developmental and foliage consumption. Neonate lepidopterous larvae were placed in controlled environment growth chambers to measure the time required to complete larval growth, and comparative foliage consumption at constant temperatures. Differences in developmental times and degree day estimates between beet armyworm and cabbage looper varied significantly with temperatures and host plant. In general, cabbage looper feeding on lettuce completed larval development at a more rapid rate and consumed more foliage than any other species-host combination. In one study, the time required to complete larval development between CL and BAW varied less than one day, but the difference in foliage consumed between the two hosts varied almost 40%. Results from these studies may provide information important for understanding the damage potential of lepidopterous larvae and optimizing use patterns for new compounds that will be integrated into management programs for leafy vegetables.
    • Influence of Cultivar and Planting Date on Strawberry Growth and Development in the Low Desert

      Maurer, Michael A.; Umeda, Kai; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      A field study was designed to determine the effects of cultivar and planting date on growth and yield of strawberries (Fragaria x annanasa D.) in the low desert. The study was conducted at the University of Arizona, Citrus Agricultural Center near Waddell, AZ. Treatments included two strawberry cultivars 'Camarosa' and 'Chandler' and three planting dates of 29 Aug., 7 Oct. and 24 Oct. 1997. There were no significant differences in fruit weight between cultivars . However, fruit number was significantly greater for 'Chandler' strawberries compared to 'Camarosa' and, therefore, fruit size was significantly smaller for 'Chandler' compared to 'Camarosa' berries. Fruit weight and number were significantly greater for both cultivars planted 29 Aug. with nearly 4 times greater production compared to the 7 Oct. and 24 Oct. plantings. Initial results of this study suggest summer planting (late Aug.) of strawberries in the low desert is necessary to produce economically viable yields.
    • Pepper Variety Trial Safford Agricultural Center, 1998

      Clark, L. J.; Walser, R.; Carpenter, E. W.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Eight varieties of bell peppers, three varieties of long green chile, two varieties of jalapeños, two varieties of yellow wax and one Serrano pepper were grown in a replicated small plot trial on the Safford Agricultural Center in 1998. Varieties were picked regularly during the growing season.
    • Application and Timing of Insecticides for Aphid Management in Head Lettuce

      Palumbo, John; Mullis, Clayton Jr.; Reyez, Francisco; Amaya, Andreas; Ledesma, Luis; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      The timing and application methods of new insecticide chemistries for aphid control were compared to imidacloprid in several studies in 1998 and 1999. Foliar applications of Fulllfill, Aphistar, Actara and Acetamiprid appear to provide an alternative method of controlling aphids on lettuce comparable to prophylactic applications of Admire. Timing applications as aphids began to colonize was critical for preventing head contamination at harvest. In addition, at planting and side dress soil applications of Platinum provided aphid control comparable to Admire. Residual activity of the new foliar alternatives appeared to differ depending on spray timing relative to aphid density and plant stage. 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 New Insecticides for Aphid Control in Green Leaf Lettuce

      Kerns, David L.; Tellez, Tony; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      New soil injected and foliar insecticides were evaluated for their efficacy towards potato aphids in green leaf lettuce. The soil injected insecticides, Platinum and V10066, both appear to be viable alternatives to Admire, providing effective aphid control through harvest or ca. 90 days post-planting. Two foliar applications of Acetamiprid or Aphistar timed ca. 14 days apart beginning at the onset of aphid colonization provided superior aphid control over Provado or Fullfill, and control similar to that of the soil injected insecticides.
    • S-1812 Lepidopterous Insect Pest Control in Broccoli Study

      Umeda, K.; Strickland, B.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      A single application of S-1812 (Valent) at 0.15 and 0.20 lb AI/A effectively reduced Plutella xylostella (diamondback moth, DBM) in broccoli compared to the untreated check. S-1812 at 0.15 lb AI/A performed similar to thiodicarb (Larvin) at 1.0 lb AI/A. S-1812 significantly reduced the DBM at 5 days after treatment (DAT) and control was effective for up to 14 DAT. S-1812 was less effective against Trichoplusia ni (cabbage looper, CL) compared to DBM control efficacy or Larvin. S-1812 reduced the development of small CL to larger sized larvae.
    • Soil-Applied Insecticides for Whitefly Control in Fall Cantaloupes

      Umeda, K.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      CGA-293343 and Admire applied to the soil at planting time provided good control of WF at rating dates 34, 45, and 52 DAP. Cantaloupes treated with CGA-293343 at 0.09 lb AI/A showed a greater increase in number of immatures after 45 DAP compared to the CGA-293343 at 0.18 lb AI/A applied on melons. At 59 DAP, the higher rate of CGA-293343 continued to reduce the number of immatures compared to the lower rate and untreated check. Admire treated melons with or without a subsequent foliar insecticide treatments showed reduced WF nymphs at 45 and 52 DAP or 10 and 17 days after treatment (DAT) of foliar applications. Foliar applications of Applaud or Asana plus endosulfan did not significantly reduce WF immatures compared to a single at-planting time application of Admire. The application of either foliar treatment did not extend the length of control beyond that offered by the Admire treatment.
    • The Effect of Irrigation Practices on the Performance of Lettuce Herbicides

      Tickes, Barry; Byrne, David N.; Baciewicz, Patti; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      The herbicides used in lettuce have changed little in more than 30 years. Poast was registered for grass control in the 1980's although preemergent applications of Kerb, Balan and Prefar have been the principal herbicides used in lettuce production since the mid 1960's. Balan was changed from a 1.5 lb./gal. Emulsifiable concentrate to a 60% dry flowable formulation in the mid 80's, Kerb has always been a 50% wettable powder and Prefar is still a 4 lb./gal. emulsifiable concentrate. Growers are constantly changing cultural practices to improve production or to become more efficient. The change in one cultural practice can, and often does, effect other cultural practices. The use of sprinklers to establish lettuce has become increasingly widespread in the Yuma area over the past 20 years. Kerb and Prefar can be mechanically incorporated into shaped beds although both are commonly incorporated with irrigation water. The change in irrigation practices during stand establishment from furrow irrigation to sprinklers has effected the performance of both Kerb and Prefar. Balan is normally disced into the soil prior to bed formation and is not as effected by irrigation practices during stand establishment. Four tests are presented in this paper that help explain the effect of irrigation practices on the performance of Kerb and Prefar.
    • Evaluation of New Fungicides for Management of Sclerotinia Leaf Drop of Lettuce in 1999

      Matheron, Michael E.; Porchas, Martin; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      In Arizona, Sclerotinia leaf drop of lettuce is caused by two different species of fungi, Sclerotinia minor and S. sclerotiorum. Relatively 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 season of 1998-99. 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 moderately high. Significant reduction in the final count of dead lettuce plants compared to nontreated plots was usually achieved by application of the standard compounds Ronilan and Rovral as well as an appropriate rate of the experimental compounds Elevate, Medallion or Serenade. Medallion and Elevate provided equivalent disease control to that of the current standard materials with 0.178 and 0.5 lb active ingredient (a.i.) per acre, respectively, compared to the current 1.0 lb a.i. per acre required with the standard compounds. 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.
    • Assessment of Fungicides Performance for Control of Powdery Mildew of Lettuce in 1999

      Matheron, Michael E.; Porchas, Martin; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Erysiphe cichoracearum is the fungus that causes powdery mildew of lettuce, a disease favored by warm and dry weather conditions. Several potential new fungicides were evaluated for control of this disease in 1999. Untreated lettuce plants were heavily infected with powdery mildew, whereas the disease was very light to virtually nonexistent in plots treated with Sovran, BAS 500, Rally and DPX-MU752. Higher levels of powdery mildew, still significantly less than that observed on untreated plants, were recorded in plots treated with the standard materials Microthiol Special and Trilogy in addition to several other compounds. The possible 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.
    • Early Postemergence Herbicide Weed Control in Onions

      Umeda, K.; MacNeil, D.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Onions treated with bromoxynil (Buctril7) or oxyfluorfen (Goal7) at the time when the first true leaf was emerging were not injured. No significant onion crop stand reduction occurred from any of the postemergence (POST) treatments. Onion height was not affected by any of the POST treatments through the season. A single application of Goal or Buctril offered up to 7 WAT of very good weed control with excellent crop safety. Onions treated at the typical 2-leaf stage of growth with Buctril or Goal exhibited no significant crop injury. Delayed and reduced control of knotweed (Polygonum aviculare) could have contributed to the decreased onion yield in the herbicide treated onions compared to the handweeded check. Onions in the untreated check were significantly reduced compared to Goal treated onions or the handweeded check.
    • Preliminary Examination of the Population Dynamics and Control of the Lettuce Aphid on Romaine

      Palumbo, John C.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Several small plot studies were conducted during the spring of 1999 to examine the population growth, distribution and control of the lettuce aphid on romaine. The lettuce aphid population developed to greater numbers more quickly and spread among plants more rapidly when compared with other aphids species under late spring growing conditions. Most of the lettuce aphids sampled were found on the hearts of the plants rather than the frame and wrapper leaves. Our preliminary efficacy studies suggest that foliar sprays, when timed properly and with proper coverage, can provide adequate control of the lettuce aphid for up to 14 days. Furthermore, significant suppression of apterous lettuce aphid populations was observed in plots where pyrethoid treatment were sprayed for thrips control. The implications of these results for future research and management of lettuce aphids in desert lettuce is discussed.
    • Diamondback Moth Control in Spring Cabbage Study

      Umeda, K.; Strickland, B.; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Spinosad (Success7), chlorfenapyr (Alert7), DPX-MP062 (DuPont), thiodicarb (Larvin7), and cryolite (Kryocide7) progressively reduced the total number of Plutella xylostella (diamondback moth, DBM) following each of three applications. Success treated cabbage had the fewest number of small-sized DBM larvae after the first application and maintained very low numbers following subsequent applications. Relative performance of the insecticides based on efficacy indicated by a seasonal average of total DBM larvae showed that Success was highly effective followed by methomyl (Lannate) and Larvin. Emamectin-benzoate (Proclaim7), Alert, and DPX-MP062 performed comparably and tebufenozide (Confirm7) and Kryocide were less effective.
    • Nitrogen Transfer in an Integrated System of Tilapia and Summer Bibb Lettuce

      Azevedo, Celicina; Olsen, Mary W.; Maughan, O. Eugene; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Nitrogen transfer from aquaculture to agriculture in integrated systems has been difficult to quantify, and the contribution of fish effluent to nitrogen utilization by crop plants is poorly documented. Therefore, labeled nitrogen, ¹⁵N, was used in a small scale integrated system in a controlled environment greenhouse to determine nitrogen transfer from the fish system and its utilization by plants. Tilapia fish were grown in m³ tanks and fed a complete diet that was amended with ¹⁵N ammonium sulfate. Fish effluent amended with ingredients of a basic nutrient solution and 0%, 25%, 50% and 100% of the recommended mineral nitrogen was used to irrigate Summer Bibb lettuce in 5 gal lysimeters in two trials. In trial 1, percent ¹⁵N recovered by lettuce was significantly higher in effluent amended with 50% mineral nitrogen as opposed to 0% or 100%. Dry weight of lettuce was significantly lower only when irrigated with effluent only (no mineral nitrogen added). In trial 2, percent ¹⁵N recovered by lettuce was significantly higher in effluent amended with 25% mineral nitrogen as opposed to 0% or 50%. In treatments with the same amount of mineral nitrogen added, addition of effluent did not affect dry weight. Although ¹⁵N recovery demonstrated efficient nitrogen transfer from the fish feed to the plants, results indicate that effluent alone does not supply sufficient nitrogen for lettuce production.
    • Efficacy of Insecticides to Diamondback Moth in Cabbage in Yuma County

      Kerns, David L.; Tellez, Tony; Byrne, David N.; Baciewicz, Patti (College of Agriculture, University of Arizona (Tucson, AZ), 1999-10)
      Commercial and experimental insecticides were evaluated for their ability to control diamondback moth (DBM) on green cabbage in Yuma, AZ. At early to mid-heading, all the insecticides evaluated appeared to offer similar control. However, on large, full sized cabbage, Asana, Alert, Lannate, Success and S-1812 offered the best DBM control, while Lorsban, Proclaim and Intrepid appeared weak. Unlike other areas of the U.S., DBM in Yuma still appears to be highly sensitive to a wide range of insecticide chemistries.