Vegetable Report 1998
ABOUT THIS COLLECTION
The Vegetable Report is one of several commodity-based agricultural research reports published by the University of Arizona.
This report was first published in 1965.
The purpose of the report is to provide an annual research update to farmers, researchers, and those in the agricultural industry. The research is conducted by University of Arizona and USDA-ARS scientists.
Both historical and current Vegetable Reports have been made available via the UA Campus Repository, as part of a collaboration between the College of Agriculture and Life Sciences and the University Libraries.
Contents for Vegetable Report 1998
- New Insecticide Alternatives for Aphid Management in Head Lettuce
- Management of Aphids and Thrips on Leafy Vegetables
- Comparison of Alternative Management Approaches for Lepidopterous Larvae in Fall Lettuce
- Commercial Field Performance of Confirm and Success on Head Lettuce and Broccoli
- Evaluation of Insect Growth Regulators for Management of Whiteflies in Melons
- Postemergence Herbicide Weed Control in Cole Crops Study
- Sweet Corn Herbicide Weed Control Study
- Cantaloupe Herbicide Weed Control Study
- Watermelon Herbicide Weed Control Study
- Noncrop Herbicide Weed Control
- Postemergence Weed Control in Cantaloupe Study
- Evaluation of Preemergence Herbicides for Onion Weed Control
- Preemergence Herbicide Combinations for Onion Weed Control Study
- Diamondback Moth Control in Spring Cabbage
- Aphid Control in Broccoli
- Aphid Control in Spinach
- Insecticides for Whitefly Control in Cantaloupe
- Leafminer Control in Cantaloupe
- Comparison of New Fungicides for Management of Powdery Mildew of Cantaloupe in 1997
- Evaluation of New Fungicides for Management of Downy and Powdery Mildew of Lettuce in 1998
- Assessment of Fungicide Performance on Control of Downy Mildew of Broccoli in 1998
- New Fungicides Evaluated for Control of Sclerotinia Leaf Drop of Lettuce in 1997 and 1998
- Tank Mixing New Insecticide Chemistries with a Pyrethroid Insecticide for Control of Lepidopterous Pests in Head Lettuce, 1997
- Efficacy of Pyrethroid Insecticides for Cabbage Looper Control in Head Lettuce, 1997
- Relative Susceptibility of Red and Green Color Forms of Green Peach Aphid to Insecticides
- Mating Disruption of Beet Armyworm in Vegetables by Synthetic Pheromone
Mating Disruption of Beet Armyworm in Vegetables by Synthetic PheromoneThe 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.
Relative Susceptibility of Red and Green Color Forms of Green Peach Aphid to InsecticidesField 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.
Efficacy of Pyrethroid Insecticides for Cabbage Looper Control in Head Lettuce, 1997Mustang 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.
Tank Mixing New Insecticide Chemistries with a Pyrethroid Insecticide for Control of Lepidopterous Pests in Head Lettuce, 1997Confirm, 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 1998Sclerotinia 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.
Assessment of Fungicide Performance on Control of Downy Mildew of Broccoli in 1998Peronospora 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.
Evaluation of New Fungicides for Management of Downy and Powdery Mildew of Lettuce in 1998Bremia 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.
Comparison of New Fungicides for Management of Powdery Mildew of Cantaloupe in 1997Powdery 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.
Leafminer Control in CantaloupeIn 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.
Insecticides for Whitefly Control in CantaloupeIn 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.
Aphid Control in SpinachSeveral 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 BroccoliIn 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.
Diamondback Moth Control in Spring CabbageIn 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.
Preemergence Herbicide Combinations for Onion Weed Control StudyDCPA (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.
Evaluation of Preemergence Herbicides for Onion Weed ControlAt 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.
Postemergence Weed Control in Cantaloupe StudyThe postemergence (POST) herbicide treatments did not cause any crop stand reduction following applications. Bentazon (Basagran®) at 0.50 lb AI /A caused marginally acceptable injury on the cantaloupe leaves. At 2 weeks after treatment (WAT), the amount of injury decreased and cantaloupe treated with Basagran at 1.0 lb AI/A showed marginally acceptable injury symptoms. Halosulfuron (Monsanto) at 0.05 to 0.10 lb AI/A caused slightly more injury (10 to 17 %) with increasing rates. Basagran at 1.0 lb Al/A gave good control ( >90 %) of morningglory and was marginal in controlling morningglory at 0.75 lb AI/A Halosulfuron at 1 WAT was marginal in controlling morningglory but improved to give acceptable control at 2 WAT. Fewer and smaller plants were removed by hand-hoeing from Basagran and halosulfuron treated plots compared to the untreated check.
Noncrop Herbicide Weed ControlParaquat 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.
Watermelon Herbicide Weed Control StudyBensulide (Prefar®), clomazone (Command®), sulfentrazone (FMC), and halosulfuron (FMC) treatments applied preemergence (PREE) gave very good weed control of prostrate pigweed (Amaranthus blitoides), lambsquarters (Chenopodium album), and common purslane (Potulaca oleracea) at 5 weeks after treatment (WAT). Bentazon (Basagran ® and halosulfuron applied postemergence (POST) alone were marginally effective at less than 85% against the pigweed species at 2 WAT and controlled lambsquarters and common purslane. POST treatments following PREE treatments were highly effective to control most weeds. Watermelon injury was acceptable for Command and halosulfuron treatments. Basagran caused slight injury when applied POST on the watermelons. Carfentrazone was not effective against the weeds present in this test site and was safe on the crop. The greatest number of marketable watermelons were harvested from plots having treatments that provided effective weed control. Command plus Prefar PREE followed by Basagran POST and Prefar PREE followed by halosulfuron POST treated watermelons yielded high numbers of marketable fruit.
Cantaloupe Herbicide Weed Control StudyClomazone (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.
Sweet Corn Herbicide Weed Control StudySeason-long near complete weed control in sweet corn was achieved with preemergence (PREE) herbicide applications of pendimethalin (Prowl®), metolachlor (Dual®), or thiafluamide/metribuzin (Axiom®) followed by postemergence applications of bentazon (Basagran®) or dicamba (Banvel®). Basagran applied alone POST gave very good control ( >93 %) of lambsquarters (Chenopodium album) and purslane (Portulaca oleracea) but did not adequately control tumble pigweed (Amaranthus albus). Prowl applied alone PREE gave acceptable control of most weeds. POST applications of prosulfuron/primisulfuron (Exceed®) caused moderate corn injury by shortening internodes and overall plant height and slight foliar chlorosis.