Citrus Research Report 2004
ABOUT THE COLLECTION
The Citrus Report, first published in 1978, is one of several commodity-based agricultural research reports published by the University of Arizona. 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 Citrus 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 Citrus Research Report 2004Insect Pest Management
- Web-based IPM Resources for Arizona's Citrus Growers Final Report
- Chemical Control and Integrated Pest Management of Woolly Whitefly
- Using Feeding Stimulants to Increase Insecticidal Control of Citrus Thrips
- Integrated Pest Management of Citrus Mealybug
- Assessing the Risk of Insecticide Resistance in Citrus Thrips in Arizona
- Response of Lemon to Micronutrient Fertilization
- Foliar applications of Lo-Biuret Urea and Potassium Phosphite to Navel Orange trees
- Results of New Cultivar Selection Trials for Lemon in Arizona – 2004-05
- Nitrogen and Phosphorus Fertilizer Requirements for Young, Bearing Microsprinkler-Irrigated Citrus, 2005 Report
Mandarin Selection Trials in Arizona - 2004-05First year yield and packout data from a trial containing 'Fina', 'Fina Sodea', 'Sidi Aissa', 'Oroval', 'W. Murcott Afourer', 'Fremont', and 'Gold Nugget; selections were collected in 2004-05. For the year, 'Fremont' had the greatest yield, but the smallest fruit size, while 'Fina' had the smallest yield, and 'W. Murcott Afourer' had the largest fruit size.
Web-based IPM Resources for Arizona's Citrus Growers Final ReportWe proposed creating a user-friendly web site that would provide independent, research-based, integrated pest management information to Arizona’s citrus growers and PCAs. This citrus IPM website, located at http://cals.arizona.edu/crops/citrus/ was created and integrated within an existing web site, the Arizona Crop Information Site (ACIS) http://cals.arizona.edu/crops. The Citrus IPM web site was launched on April 15, 2004.
Nitrogen and Phosphorus Fertilizer Requirements for Young, Bearing Microsprinkler-Irrigated Citrus, 2005 ReportHigher nutrient and water use efficiency are possible with microsprinkler-irrigated citrus compared to flood-irrigated citrus. Therefore, new N and P fertilizer recommendations are needed for microsprinkler-irrigated citrus. The objectives of these experiments were to i) determine the effects of N applications on tree growth, fruit yield, fruit and juice quality, and N and P removal in fruit for microsprinkler-irrigated navel oranges; ii) determine the effects of P applications on tree growth, fruit yield, fruit and juice quality, and N and P removal in fruit, and iii) develop Best Management Practices for N and P fertigation of microsprinkler-irrigated citrus. Field experiments were conducted at the University of Arizona Citrus Agricultural Center in separate blocks of 'Newhall' and 'Fukumoto' navel oranges, both on 'Carrizo' rootstock. In each block, ten treatments, consisting of all possible combinations of 5 N rates (0, 0.2, 0.4, 0.6, and 0.8 lb N/tree/yr) and 2 P rates (0, 0.2 lb P/tree/year) were applied to five replicate trees per treatment. Maximum yields of the ‘Newhall' trees were 132 lb fruit/tree at a N rate of 0.5 lb N/tree/yr. Maximum yield of the 'Fukumoto' trees was119 lb fruit/tree at 0.5 lb N/tree/yr. Both varieties maintained appropriate leaf N and P concentrations at the yield-maximizing N rates. Total N in the fruit accounted for about 60 % of the N applied at the yield-maximizing N rates in both varieties. The results confirmed that microsprinklers effectively reduced the amounts of N fertilizer needed while maintaining adequate N status in the trees, with excellent N use efficiency.
Chemical Control and Integrated Pest Management of Woolly WhiteflyFive foliar insecticide treatments (Esteem, two rates of Provado, two rates of Applaud, Prev-am, and Danitol + Lorsban) were evaluated for their control of woolly whitefly infestations in grapefruit. All of these products demonstrated efficacy in mitigating woolly whitefly populations. Danitol + Lorsban was the best knock-down treatment evaluated, but for sustained control, Esteem appeared to be most effective. Applaud demonstrated good activity, but the rate we tested may be a little low; the 1.0 lb/ac rate should be evaluated. Provado at 19 oz/ac was a good treatment, while the 10 oz/ac rate appears to be sub-par. Prev-am is a oil based contact material and demonstrated good initial activity. Soil injections of 16 and 32 oz/ac of Admire were very effective against WWF, and there were no detectable differences between the two rates. Previous experiments with soil injections of Admire in citrus suggested that as much as six weeks needs to pass before the trees have enough time to adequately take up the Admire from the soil. However, these data suggest that smaller trees, about 10 ft tall, may require as little as two weeks to pick up the material.
Using Feeding Stimulants to Increase Insecticidal Control of Citrus ThripsCarzol and Success with and without the addition of the feeding stimulants molasses and bee-collected pollen were evaluated for their control of citrus thrips on lemons on the Yuma Mesa. Although normal use rate of Carzol and Success were efficacious toward citrus thrips, the addition of either molasses or pollen to these insecticides as a means of increasing efficacy at low rates was not encouraging. At no point did the feeding stimulants appear to increase the efficacy of the same rate of Carzol when used alone, and it appeared that the additives may have actually decreased the efficacy of Success.
Assessing the Risk of Insecticide Resistance in Citrus Thrips in ArizonaBioassay with Dimethoate, Carzol, Danitol, Baythroid and Success were conducted on citrus thrips collected from the Yuma Mesa to determine if insecticide resistance to these insecticides occurred. Low to moderate levels of resistance were detected for Dimethoate, Carzol and Danitol, and one population exhibited a high level of resistance to Baythroid. No resistance was evident for Success. Susceptibility to Success was much higher for the Yuma populations relative to populations previously reported in California.
Integrated Pest Management of Citrus MealybugFoliar-applied insecticides and the soil-applied insecticide, Admire, were evaluated for their ability to control citrus mealybug on lemons while having a minimal impact on parasitoids. All of the foliar-applied insecticide exhibited activity towards citrus mealybug. The standard insecticide, Lorsban, performed very well, but since this product is especially harmful to parasitoids it is not considered to have a good fit in IPM programs where parasitoid conservation is emphasized. The currently labeled alternative, Applaud, was an effective treatment and should be considered for citrus mealybug control to avoid destruction of parasitoids. Several experimental insecticides showed promise: NNI-850, NNI-750C and NNI-010. However, NNI-0101 at the lower rate of 0.24 lbs-ai/ac appeared to be weak. The addition of narrow range crop oil, NR-415 at 1.0 gal/ac, appeared to be beneficial for initial mealybug knock-down, especially for the slower acting insecticides such as Applaud. Soil injection of Admire at 16 and 32 oz/ac appeared to have very good activity, but due to variability in the mealybug population, more data should be collected to confirm this finding.
Lemon Rootstock Trials in Arizona – 2004-05In a rootstock evaluation trial planted in 1993, five rootstocks, ‘Carrizo’ citrange, Citrus macrophylla, ‘Rough Lemon’, Swingle citrumelo and Citrus volkameriana were selected for evaluation using 'Limoneira 8A Lisbon' as the scion. 1994-2004 yield and packout results indicate that trees on C. macrophylla, C. volkameriana and ‘Rough Lemon’ are superior to those on other rootstocks in both growth and yield. C. macrophylla is outperforming C. volkameriana. For the second year in a row, ‘Rough Lemon’ trees performed similarly to C. macrophylla and better than C. volkameriana. ‘Swingle’ and Carrizo’ are performing poorly. In two other rootstock evaluation trials, both planted in 1995, C. macrophylla and/or C. volkameriana are outperforming other trifoliate and trifoliate-hybrid rootstocks under test.
Results of New Cultivar Selection Trials for Lemon in Arizona – 2004-05Three lemon cultivar selection trials are being conducted at the Yuma Mesa Agriculture Center in Somerton, AZ. Data from these trials suggest that ‘Limonero Fino 49’ selections may be a suitable alternative for the varieties most commonly planted in Southwest Arizona today. ‘Femminello’ and ‘Villafranca’ might also be planted on an experimental basis.
Cultivar Selection Trials of Navel Orange in Arizona for 2004-05Two orange cultivar trials have been established in Arizona, one at the Yuma Mesa Agricultural Center, Yuma, AZ and one at the Citrus Agriculture Center, Waddell, AZ. For the navel orange trial in Yuma, all the selections had improved yields in 2004-05. ‘Fisher’ navel continues to have the greatest yield, but is quite granulated. Of the rest in the Yuma trial, ‘Lane Late’ had the best quality and yield. For the Waddell trial, the fourth year data has been collected, and suggests that ‘Fisher’, ‘Beck-Earli’, ‘Chislett’ and ‘Lane Late’ are outperforming the other cultivars tested to date.
‘Lisbon’ Lemon Selection Trials in Arizona – 2004-05Four 'Lisbon' lemon selections, 'Frost Nucellar', 'Corona Foothills', 'Limoneira 8A' and 'Prior' were selected for evaluation on Citrus volkameriana rootstock. 2004-05 results indicate that the 'Limoneira 8A Lisbon' and ‘Corona Foothills Lisbon’
Foliar applications of Lo-Biuret Urea and Potassium Phosphite to Navel Orange treesThis experiment was established in January 2000 in a block of ‘Washington’ navel orange trees at Verde Growers, Stanfield, AZ. Treatments included: normal grower practice, winter low biuret (LB) urea application, summer LB urea application, winter LB urea application plus winter and spring potassium phosphite, winter LB urea application plus summer potassium phosphite, and normal grower practice plus spring potassium phosphite. Each treatment was applied to approximately four acres of trees. For 2000-01, yields ranged from 40 to 45 lbs. per tree, and there was no effect of treatments upon total yield, and only slight effect upon fruit size, grade and quality. For 2001-02, there was a slight effect of treatment upon yield as LB urea led to improved yield, while potassium phosphite led to reduced yield. Normal grower practice was intermediate between these two extremes. For 2002-03, we noted a large increase in yield, however the yield data was lost when the block was inadvertently harvested. For 2005, there was no effect of treatments upon total yield.
Response of Lemon to Micronutrient FertilizationA study was initiated in the spring of 2003 to evaluate the response of lemons to soil and foliar applied micronutrients for two growing season (2003-2005). Soil applied Fe, Zn, Mn, and Cu was applied in sulfate form and B as Solubor in shallow holes around the skirt of each tree. Foliar applied micronutrients were all applied as “Metalosate” products. Lemon leaf tissue analyses show marginal levels of Zn, Mn, and Cu throughout the study. In 2003-2004, soil fertilization sometimes increased leaf nutrient composition but there was no effect to foliar fertilization. In 2004-2005, ,leaf B and Zn increased to soil fertilization and leaf Mn and Cu increased to foliar fertilization Overall, there were no significant differences in yield or quality to micronutrient fertilization in either growing season.