Vegetable Report 1989
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 1989
- International Asparagus Cultivar Trial
- Oriental Vegetable Cultivar Trials
- Yuma Broccoli Variety Trials, 1987-1988
- Yuma Cauliflower Variety Trials, 1987-1988
- Sweet Corn Cultivar Evaluations in Arizona, 1987-1988
- Early Fall Lettuce Cultivar Trials in Western Arizona, 1988
- Mid-fall Planted Lettuce Cultivar Trial at Yuma, 1988-89 Season
- Comparison of Two Sweet Corn Types for Field Quality Holding
- A Study of Timing of Sweet Corn Plantings for Fall Harvest in Central Arizona
- Vegetable Transplant Stress Conditioning
- Vegetable Transplant Container Trial
- Tolerance of Terpary and Navy Beans to Different Salt Levels in Irrigation Water
- Bell Pepper Row Cover and Drip Irrigation Test
- Asparagus Response to Water and Nitrogen
- Nitrogen and Water Effects on the Growth, Yield and Quality of Drip Irrigated Sweet Corn
- Enhanced Growth of Drip Irrigated Sweet Corn Using a Nitrification Inhibitor
- Effect of Gypsum on Lettuce in Marana, 1988
- Resistance in Cultivated and Wild Lettuce to Lettuce Infectious Yellows Virus
- Detection of Lettuce Infectious Yellow Virus (LIYV) in Greenhouse and Field Inoculated Plots Using an Indirect Enzyme-linked Immunosorbent Assay (Indirect ELISA)
- Assessment of Virus Disease Incidence and Whitefly Population in an Isolated Agroecosystem in Central Arizona
- Use of Stylet Oil to Slow the Spread of Lettuce Infectious Yellows Virus
- Improved Management Strategies from Basic Biology of Whiteflies
- Powdery Mildew of Cantaloupe -- Evaluation of New Fungicides for Disease Control
- Sclerotinia Leaf Drop on Lettuce -- Evaluation of New Fungicides for Disease Control
- Honeydew Measles: A Potential Threat to Commercial Honeydew Production
- Leafminer Fly New to Arizona Spreads Across State, Causes Severe Damange to Lettuce
- Control of Liriomyza trifolii Larvae in Head Lettuce
- Evaluation of Head Lettuce Varieties for Liriomyza trifolii Leafminer Populations
- Weed Control Investigations in Deserted Irrigated Asparagus
Honeydew Measles: A Potential Threat to Commercial Honeydew ProductionMeasles of honeydew melons is not a common problem, but melon growers should be aware that it can cause severe economic damage, under the right environmental conditions. At least one Pinal County grower suffered significant loss during an outbreak of this disease in September 1987.
Sclerotinia Leaf Drop on Lettuce -- Evaluation of New Fungicides for Disease ControlLeaf drop of lettuce, caused by Sclerotinia sclerotiorum, is a sporadic, but destructive, disease in Arizona. Field trials were established during 1987 and 1988 to evaluate potential new fungicides for disease control. Ronilan and Rovral, the two materials currently registered for use on lettuce for Sclerotinia leaf drop, were consistently among the most effective fungicides for disease control. Levels of disease control equivalent to that provided by Rovral and Ronilan were observed with CGA-449, SC-0854 SDS-65311, Bay HWG 1608, and Spotless. These field tests have identified several potential new fungicides for control of leaf drop of lettuce caused by S. sclerotionan.
Powdery Mildew of Cantaloupe -- Evaluation of New Fungicides for Disease ControlPowdery mildew of cantaloupe, caused by Sphaerotheca fuliginea, is a perennial and often devastating disease in Arizona. During 1987 and 1984 potential new fungicides were evaluated in field trials for disease control. In 1987, Bayleton, Rally and Spotless provided significant disease control. In 1984, Rally and Spotless significantly reduced development of powdery mildew, while Bayleton and Tilt were less effective. Uneven development of powdery mildew within the plot may partially explain the apparent lack of significant disease control in 1988 by Bayleton and Tilt.
Improved Management Strategies from Basic Biology of WhitefliesA series of experiments has been conducted aimed at learning more about whitefly biology. We learned that: 1) whitefly eggs imbibe water from plant tissue; 2) the wax particles on exterior body surfaces may be antifungal; 3) mature lettuce is not a good host for whiteflies and; 4) there is a migrating morph. All these facts are of practical importance.
Use of Stylet Oil to Slow the Spread of Lettuce Infectious Yellows VirusThe use of stylet oil to slow the spread of the whitefly- transmitted vines, lettuce infectious yellows, shows sufficient promise to plan for expanded research efforts. The main positive results were a slower buildup of virus infection and a larger number of marketable heads in the block of lettuce sprayed with oil. Weight (in grams) of individual heads could be correlated with time of infection in that the lowest weights and marketability ratings occurred in plants infected earliest in the season. Whether they were front treated or untreated plots, marketable heads weighed an average of 784 grams; unmarketable heads weighed 491 grams. The key difference is that, on the average, five marketable heads of lettuce were in the oil- treated plots for every three in the untreated plots. A follow-up experiment will be conducted in 1989 to determine if these preliminary positive results indicate that stylet oil treatment may be a practical control method for slowing the spread of L1YV.
Assessment of Virus Disease Incidence and Whitefly Population in an Isolated Agroecosystem in Central ArizonaA survey study was undertaken to identify the plant viruses, to document the occurrence of virus diseases, and to document the seasonal population dynamics of insect vectors in a semi-isolated agricultural site in Central Arizona. A typical year-round cropping history at the site consists of cotton and seasonal sequences of vegetables. The most abundant insects caught using 24-hr exposures of yellow sticky traps were whiteflies (Trialeurodes abutilonea Haldeman and Bemisia tabaci Genn.) and the cotton (or melon) aphid (Aphis gossypii Glover). Of the three, only B. tabaci and A. gossvpii are recognized as virus vectors in Arizona. The most prevalent plant virus identified in vegetable crops and/or weeds was lettuce infectious yellows virus (LIYV), a whitefly-transmitted virus. The virus was detected in lettuce, (greenleaf, romaine, iceberg, red leaf) watermelon, cantaloupe, spinach, and cilantro. In addition, the watermelon curly mottle/squash leaf curl virus complex (WCMoV-SLCV), watermelon mosaic virus 2 (WMV-2) zucchini yellow mosaic virus (ZYMV), cucumber mosaic virus (CMV), and squash mosaic virus (SqMV) were identified in cucurbits at various times and locations throughout the season.
Detection of Lettuce Infectious Yellow Virus (LIYV) in Greenhouse and Field Inoculated Plots Using an Indirect Enzyme-linked Immunosorbent Assay (Indirect ELISA)Lettuce infectious yellows virus (LIYV), a recently recognized plant virus, causes dramatic yellowing symptoms and severe diseases in a wide range of vegetable crops in Arizona, adjacent southwestern states and Mexico. Until now, the only available diagnostic method was a time-consuming bioassay that used the insect vector to transmit the virus, with subsequent manipulation of indicator plants. A rapid, sensitive diagnostic technique (termed an indirect enzyme-linked immunoassay, called indirect ELISA) system was developed to detect lettuce infectious yellows virus (LIYV) in infected plant material. A virus specific antibody was made to viral capsid protein which was purified by polyacrylamide gel electrophoresis. The indirect ELISA system was optimized and used to detect viral antigen in greenhouse-inoculated melons. The system was subsequently adapted to detect LIYV in symptomatic and asymptomatic weed and cultivated plant species collected from infected fields near Yuma and in central Arizona. The indirect ELISA system described here allows for the detection of approximately 100 ng of virus per well. The LIYV was detectable in symptomatic (but not in asymptomatic) leaves of melon plants infected with the virus. In contrast, the virus could be detected in both symptomatic and symptomless cheeseweed plants collected in the field. The optical density readings for infected weed species were generally lower than those for cultivated species, such as melons, lettuce, and spinach, suggesting that there is less virus in the weed hosts tested than in infected, cultivated hosts.
Resistance in Cultivated and Wild Lettuce to Lettuce Infectious Yellows VirusIn 1988, Arizona's early- season lettuce crop was plagued by disease and insect problems, both intensified by unseasonably high temperatures. In the western Arizona production area, an epidemic of lettuce infectious yellows (LIY) resulted in serious economic losses to growers. The yellows disease is incited by the LIY virus (LIYV), a plant virus transmitted by the sweet potato whitefly [Bemisia tabaci (Gene.)]. Disease symptoms in lettuce include stunted growth, rolling yellowing and /or reddening of infected leaves; necrotic lesions appear at or near the leaf margins at latter stages of the disease. LIYV has a wide host range which increases the difficulty of isolating lettuce fields from LIYV infected or whitefly-infested fields; also, whiteflies are resistant to insecticides. Therefore, host-plant resistance appears to be the most promising means of reducing losses due to this disease. To initiate a breeding program, commercial lettuce cultivars and breeding lines (Lactuca sativa L.), and related, cross-breeding wild lettuce species (L. serriola L. and L. saligna L.) were screened for resistance to LIYV in the western Arizona production area using natural inoculation by residence whiteflies.
Effect of Gypsum on Lettuce in Marana, 1988Gypsum was applied preplant on spring lettuce at rates of zero, 2 tons per acre, and 4 tons per acre. There were no significant differences in carton yields or in carton weights. Postharvest soil analyses showed that the application of four tons of gypsum per acre significantly increased the calcium and magnesium levels in the saturated paste solution. There were no significant effects of gypsum application on ESP and SAR values, nor in pH or sodium concentrations.
Enhanced Growth of Drip Irrigated Sweet Corn Using a Nitrification InhibitorA field experiment using subsurface drip irrigation was conducted at the Maricopa Agricultural Center on a Casa Grande sandy loam to evaluate the effect of varying nitrogen rates on the growth and yield of 'Jubilee' sweet corn when applied with, and without the nitrification inhibitor, nitrapyrin (N-Serveᴿ). N treatments of 89, 134 and 2671bs. N/acre were applied as ammonium sulfate to one meter miniplots in three split applications between the V2 and the V10 growth stages. Individual N-Serveᴿ application rates were 0.5 lbs/acre. All solutions were applied through buried, perforated PVC tubing to simulate application through the buried drip irrigation system. The inclusion of N-Serveᴿ significantly increased dry matter accumulation, number of total ears and number of marketable ears /plant at all N levels. Plant tissue analysis suggested that enhanced uptake of ammonium -N as well as reduced leaching of nitrate-N contributed to this growth response to N- Serveᴿ.
Nitrogen and Water Effects on the Growth, Yield and Quality of Drip Irrigated Sweet CornA complete factorial experiment using three nitrogen (44, 106 and 160 lbs N/acre) and three water rates (60, 100 and 130% consumptive use) examined the specific management criteria necessary for obtaining optimum yield and quality of drip -irrigated 'Jubilee' sweet coni. The crop was planted on I March and harvested on 10 June, with an 86 /50°F heat unit accumulation of 1738. When present, a nitrogen deficiency greatly decreased marketable yield, number of marketable ears/plant, mean ear weight, ear length and tip fill. Higher moisture rates generally had less effect on yield and quality than did N rates; however, increasing water rates significantly increased marketable yields and plant height, improved tip fill and lessened the occurrence of blank kernels. The effect of N and water rates on N and dry matter accumulation and on diagnostic plant tissue testing results for sweet corn are also presented. The maximum marketable yield obtained in this experiment was 7.8 tons per acre, using 160 lbs N/acre and 21.1 inches of irrigation water.
Asparagus Response to Water and NitrogenThe relationships of asparagus yields to varying levels of water and nitrogen were determined. Maxinuem yields of 345, 560 and 300 crates/acre were produced for asparagus crowns that were 3, 4 and 5 years old, respectively. A total seasonal water depletion rate of 98 inches was calculated for the fern growing season. Optimum nitrogen applications were estimated at approximately 350 -400 lb/ac.