Vegetable Report 1999
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 1999Defoliants
- Comparison of New Fungicides for Management of Downy Mildew of Broccoli in 1999
- New Fungicides Evaluated for Control of Powdery Mildew of Cantaloupe in 1998
- Evaluation of New Fungicides for Management of Sclerotinia Leaf Drop of Lettuce in 1999
- Assessment of Fungicides Performance for Control of Powdery Mildew of Lettuce in 1999
- Evaluation of Preemergence Herbicides for Early Season Onion Weed Control
- Canarygrass Control in Wheat
- The Effect of Irrigation Practices on the Performance of Lettuce Herbicides
- Early Postemergence Herbicide Weed Control in Onions
- Evaluation of Herbicides for Cantaloupe Weed Control
- Garbanzo Bean Weed Control Study
- Postemergence Herbicide Weed Control in Cantaloupes
- Preemergence Herbicide Combinations for Onion Weed Control
- Prowl and Prefar for Onion Weed Control
- Sweet Corn Herbicide Weed Control Study
- Timing of Postemergence Herbicides for Onion Weed Control
- Efficacy of Insecticides to Diamondback Moth in Cabbage in Yuma County
- Evaluation of Knack for Aphid Control in Green Leaf Lettuce
- Evaluation of New Insecticides for Aphid Control in Green Leaf Lettuce
- New Insecticides and Tank Mix Combinations for Worm Control in Lettuce
- Studies of Resistance of Beet Armyworm (Spodoptera exigua) to Spinosad in Field Populations from the Southern USA and Southeast Asia
- A Practical Approach for Managing Lepidopterous Larvae with in Head Lettuce
- Application and Timing of Insecticides for Aphid Management in Head Lettuce
- Cross Commodity Management of Whiteflies and Chemical Efficacy in Arizona
- Field Performance of Admire Against Silverleaf Whitefly on Commercial Iceberg Lettuce, 1993-1998
- Preliminary Examination of the Population Dynamics and Control of the Lettuce Aphid on Romaine
- Residual Efficacy of New Insecticide Chemistries Against Cabbage Looper in Head Lettuce
- Diamondback Moth Control in Spring Cabbage Study
- Evaluation of Foliar Insecticides for Whiteflies in Cantaloupes
- Leafminer Control in Cantaloupes
- S-1812 Lepidopterous Insect Pest Control in Broccoli Study
- Soil-Applied Insecticides for Whitefly Control in Fall Cantaloupes
- Refinement of Release Techniques for Whitefly Parasitoids
- Potential of Particle Film Technology for Insect Management in Crisp Head Lettuce
- Implementation of a Pest Monitoring Network for Vegetable Growers in Yuma County
- Influence of Cultivar and Planting Date on Strawberry Growth and Development in the Low Desert
- Fertigation Frequency Effects on Yield and Quality of Subsurface Drip-Irrigated Broccoli
- Green Bean Variety Trial, Safford Agricultural Center, 1998
- Sweet Corn Variety Trial Safford Agricultural Center, 1998
- Pepper Variety Trial Safford Agricultural Center, 1998
- Tomato Variety Trial Safford Agricultural Center, 1998
Development and Consumption Rates for Lepidopterous Larve as Influenced by Host-Plant and TemperatureSeveral 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.
Effect of Onion Bed Shape on Accumulation of Soluble Salts and SodiumAn experiment was conducted to examine the effectiveness of knifing a vshaped notch into the center of raised onion beds for reducing soluble salt accumulation in the seed rows. Sodium salts accumulated within an 18 inch wide band in the top six inches of the knifed raised bed profile. Sodium salts accumulated primarily within a narrow six inch wide band, and to a somewhat lesser extent, within an 18 inch wide band in the top six inches of the conventional raised bed profile. Total soluble salts accumulated primarily within a six inch wide band in the top six inches of the knifed and conventional onion raised bed profiles.
Nitrogen Transfer in an Integrated System of Tilapia and Summer Bibb LettuceNitrogen 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.
Tomato Variety Trial Safford Agricultural Center, 1998Four slicing and two Roma-type tomato varieties were grown in a replicated small plot trial on the Safford Agricultural Center in 1998. Varieties were picked regularly during the growing season with total tonnage picked being tabulated and plot weights by variety shown graphically against time during the season. Balboa variety of slicing tomato and Toro variety of Roma-type tomato were the highest yielding varieties with yields of 69 and 76 tons per acre respectively.
Pepper Variety Trial Safford Agricultural Center, 1998Eight 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.
Sweet Corn Variety Trial Safford Agricultural Center, 1998Eight sweet corn varieties were grown in a replicated small plot trial on the Safford Agricultural Center in 1998. Snow White had the highest yield per acre with several of the other varieties producing very acceptable yields. Yields seen in the small plots may not be obtainable in commercial fields, but yield relations between varieties should be the same for both situations.
Green Bean Variety Trial, Safford Agricultural Center, 1998Twelve green bean varieties were grown in a replicated small plot trial on the Safford Agricultural Center in 1998. Varieties were picked regularly during the growing season. Yields are shown in tabular form and also graphically to indicate how each variety performed throughout the season. Rapids produced the highest yield with a total over 1.3 tons per acre. Two other varieties, Shade and HMX 6999, also performed well with yields over 1.0 tons per acre.
Fertigation Frequency Effects on Yield and Quality of Subsurface Drip-Irrigated BroccoliSubsurface drip irrigated broccoli received experimental combinations of N rate (176 and 268 lb N/ac, and fertigation frequency (daily, weekly, bi-weekly, monthly) at the Maricopa Agricultural Center during winter 1998-99. Marketable broccoli yields were increased slightly with N applications of 268 lb/acre compared to 176 lb/acre. However, neither marketable yield, head diameter, nor petiole nitrate concentrations were significantly affected by fertigation frequency. Nitrogen fertigation frequency does not seem to be a critical management variable for subsurface drip irrigated broccoli grown on medium-textured soils in Arizona.
Influence of Cultivar and Planting Date on Strawberry Growth and Development in the Low DesertA 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.
Implementation of a Pest Monitoring Network for Vegetable Growers in Yuma CountyAn insect pest monitoring network spanning the major growing areas in Yuma was implemented in 1998-1999. This project was designed to measure the relative activity and movement of adult populations during the growing season and provide important information to growers and PCA’s. A series of pheromonebaited and yellow sticky traps were placed in 11 locations among the growing areas in the Yuma, Gila and Dome Valleys in Yuma county. Numbers of adults / trap /night were recorded weekly from September-April. Seasonal differences in insect species activity and abundance among locations were observed, but difficult to precisely explain because of the lack of historical trap data. Information gathered from the trapping network will provide historical baseline data for pest activity on an area wide basis from which relationships between insect trap captures and seasonal factors that influence their activity and abundance may be explained. The results of the monitoring network during the 1998-1999 growing season for is provided in this report.
Potential of Particle Film Technology for Insect Management in Crisp Head LettuceA new insect management technology known as "particle film" technology (Surround) was evaluated for it potential for control early fall pests of head lettuce in Yuma, AZ. Surround did appear to slightly reduce larval population of cabbage looper, beet armyworm and Heliothis, but not enough to be considered a commercially effective treatment. Additionally, Surround appeared to antagonize Success’s activity towards cabbage loopers. Against whiteflies, Surround did appear to reduce ovipositioning, but resultant impact on the nymph population could not be adequately assessed. Overall, Surround does not appear to have good fit in the pest management system in leafy vegetables in Yuma, AZ.
Refinement of Release Techniques for Whitefly ParasitoidsAlthough they are currently effectively controlled by chemicals, sweet potato whiteflies have the potential to once again be a dominant pest in Arizona vegetables. We need to explore alternatives such as biological control so that we are not reliant solely on pesticides. We have been examining dispersal by the whitefly parasitoid Eretmocerus sp. in order to find more effective ways to deploy these agents in the field. We have learned in the laboratory that these wasps are efficient flyers since they are capable of moving into strong winds for more than 30 min. We also now know that most flight takes place within a short distance of the release point. We also have a better understanding of differences between male and female flight. This, along with other information we have obtained, will lead to our ability to effectively release these and parasitoids of other insect pests as well.
Soil-Applied Insecticides for Whitefly Control in Fall CantaloupesCGA-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.
S-1812 Lepidopterous Insect Pest Control in Broccoli StudyA 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.
Leafminer Control in CantaloupesCantaloupe 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.
Evaluation of Foliar Insecticides for Whiteflies in CantaloupesA single application of buprofezin (Applaud7) at 0.38 lb AI/A had the fewest number of adult whiteflies (WF) on rating dates at 13, 21, and 27 days after treatment (DAT). The number of immature WF at 21 DAT of a single Applaud application ranged from 0.8 to 5.2 nymphs/leaf, significantly less than the untreated. Applaud treatments were effective in minimizing the immatures for 21 DAT of a single application and then numbers began to increase before 27 DAT. Applaud plus two subsequent weekly applications of bifenthrin (Capture7) plus endosulfan (Thiodan7, Phaser7) was almost similar to single applications of Applaud alone and adult numbers were also low. Weekly applications of the pyrethroids plus endosulfan reduced the adult WF relative to the untreated at 1 week after treatment (WAT). At 2 WAT of the third application, fenpropathrin (Danitol7) and Capture continued to show reduced numbers of adults and esfenvalerate (Asana7) was similar to the untreated. Danitol treatments had numerically fewer adults than Capture which was lower than Asana. The lowest adult and immature WF populations were observed season-long in the CGA-293343 (Novartis) treated cantaloupes. Both rates, 0.067 and 0.09 lb AI/A performed similarly and numerically slightly fewer nymphs were observed for the higher rate. CGA-293343 plus CGA-215944 (pymetrozine, Fulfill7) performed similar to the two rates of CGA-293343 alone.
Diamondback Moth Control in Spring Cabbage StudySpinosad (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.
Residual Efficacy of New Insecticide Chemistries Against Cabbage Looper in Head LettuceSeveral new insecticide chemistries were evaluated and compared with standard chemistries for residual efficacy against cabbage looper in lettuce. Four field trials were conducted at thinning, and heading stages of lettuce. These replicated trials clearly demonstrate that the new insecticides provide a solid 7 day residual efficacy (>90% control) following spray applications. Overall, Success at rates ranging from 4.5-6.0 oz/acre appeared to provide the most consistent residual activity on larvae present on plants at time of application. Confirm, appeared to have less consistent residual, but control was generally similar to Success. The newer compounds Proclaim and Avaunt, showed good residual efficacy for up to 7 days, and will be a welcome additions to the growers insecticide arsenal. Finally, the fact that all of these compounds are effective against large larvae, in part explains their consistent residual activity on lettuce.
Preliminary Examination of the Population Dynamics and Control of the Lettuce Aphid on RomaineSeveral 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.
Field Performance of Admire Against Silverleaf Whitefly on Commercial Iceberg Lettuce, 1993-1998Whitefly populations in the Yuma area have been reduced to levels that growers can cost-effectively manage. Data from our studies suggest that these declines in pest populations are largely attributed to the use of Admire 2F (imidacloprid) soil treatments. Relative to the outbreaks in 1993-1994, whitefly populations during the past four growing seasons have remained at sub-economic levels on lettuce crops throughout the growing areas in Yuma This chemical has provided excellent control of whiteflies on fall lettuce, and aphids on spring lettuce. After 6 years of evaluation in commercial fields, the product appears to remain highly efficacious, maintaining good residual activity. Studies in 1998 on fall broccoli and melons crops further support this conclusion. Factors responsible for this sustained efficacy of Admire are discussed.