Citrus Research Report 1988
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 1988
- The Effects of Navel Orange Prorate Suspension on F. O. B. to Retail Price Spreads
- Effects of Canopy Position on Quality, Photosynthesis and Mineral Nutrition of Four Citrus Varieties
- Chemical Freeze Protection of Citrus 1987/1988
- Distribution of Two Species of Phytophthora Within the Citrus Acreage in Arizona
- Sodium Tetrathiocarbonate - Potential New Fungicide for Control of Phytophthora in Citrus Groves
- Update on Fuller's Rose Beetle in Arizona
- Control of Ctirus Thrips by Avermectin
- Pesticide Efficacy Trials for Citrus Flat Mites on Oranges, 1988
- Eradication of California Red Scale in Yuma County - An Ongoing Battle
- Potential Rootstocks for "Redblush" Grapefruit in the Desert
- Performance of Various Lemon Types in Southwest Arizona
- Selections of Blood Oranges for Arizona Growers
Selections of Blood Oranges for Arizona GrowersInterest in growing blood oranges in Arizona has been increasing in recent years, especially for producing fruit for sale in roadside stands. The Arizona Cooperative Citrus Registration Certification Program now has four selections from which to choose: 'Moro', 'Tarocco', 'Sanguinelli', and 'Ruby'. Each one has distinct advantages and disadvantages that should be considered before making a selection.
Performance of Various Lemon Types in Southwest ArizonaLong term comparisons of 8 types of lemons (Citrus limon Bunn. F.) on Macrophylla (Alemow) (C. macrophylla) rootstock regarding yield, tree growth, and quality under the arid conditions of the Southwest were studied. 'Foothill Lisbon' showed significantly higher cumulative yield and total acid than 'Monroe Lisbon', 'Prior Lisbon', Eureka strains, and Villa Franca, and had larger fruit than other Lisbon strains. 'Prior Lisbon' produced larger tree canopy than all other strains. Overall, Eureka strains and 'Villa Franca' had lower relative cumulative yield, yield efficiency, canopy volume, soluble solids, total acid and fruit seed content , but higher soluble solids to acid ratio than Lisbon strains. All factors considered 'Foothill Lisbon' and 'Prior Lisbon' have good potential for planting in the arid climate and sandy soil of Southwest, when Macrophylla rootstock is to be used.
Potential Rootstocks for "Redblush" Grapefruit in the DesertEffects of 12 rootstocks on yield, yield efficiency, bearing potential and quality of 'Redblush' grapefruit were measured and potential rootstocks recommended for the arid climate of southwest Arizona. Trees on 'Palestine' sweet lime and 'Volkamer' lemon produced high cumulative yield but small fruit. Trees on Macrophylla (Alemow) produced higher yields after 5 years of planting and had significantly higher mean yield efficiency than trees on other rootstocks. Thus, Macrophylla rootstock could be a good choice for 'Redblush' at the standard spacing and perhaps at high density spacing in southwest Arizona. Fruit of trees on 'Carrizo' and 'Troyer' citranges were largest. Trees on 'Savage' citrange had lowest yield thinnest peel and highest levels of total soluble solids and soluble solids /acid ratio. Fruit of trees on 'Swingle' citrumelo or C.P.B. 4475 rootstock consistently had higher percentage acid than those on other rootstocks. Considering yield and /or various quality factors, 'Volkamer' lemon, rough lemon , 'Palestine' sweet lime, 'Oklawaha' sour orange and particularly 'Carrizo' citrange are suitable for 'Redblush' grapefruit in the arid Southwest. 'Savage' citrange, 'Ichang' pummelo , 'Cleopatra' mandarin, and 'Swingle' were poor yielding rootstocks for 'Redblush ' grapefruit, and therefore undesirable for planting under the standard spacing of this experiment. 'Savage' and 'Swingle' might be good choices at higher densities because they have yield efficiency, high maximum bearing potential and quality.
Eradication of California Red Scale in Yuma County - An Ongoing BattleDuring the last 15 years, the Yuma County Citrus Pest Control District (YCCPCD) has twice eradicated infestations of California Red Scale within the district. A third infestation, found in late 1984 is currently being fought with eradication as the goal.
Control of Ctirus Thrips by AvermectinTwo rates of Avermectin were mound- applied; one treatment of Avermectin B one of Carzol were applied by air to citrus in April for control of citrus thrips. Plots were sampled by beating new terminal growth and counting thrips. Ground applications had fewer thrips than applications made by air. Avermectin B1 treatments had significantly fewer thrips than Carzol at all sample dates.
Update on Fuller's Rose Beetle in ArizonaInitial studies of Fuller rose beetle (FRB) biology have found some adult emergence in late June and early July. No adults woe found in foliage in May or early June, nor was activity noted in August and early September. FRB were not found in early October, but they began expected major emergence in mid-October. Several FRB collected did not have fused wings, atypical for this species. This finding suggests flight ability in FRB, currently unknown to occur.
Sodium Tetrathiocarbonate - Potential New Fungicide for Control of Phytophthora in Citrus GrovesSodium tetrathiocarbonate (STTC) releases carbon disulfide when added to water and applied to soil. Laboratory tests were conducted to determine the effect of this chemical on growth and sporulation of Phytophthora citrophthora and P. parasitica, which cause Phytophthora gummosis and mot rot of citrus in Arizona Zoospore motility, zoospore cyst viability, sporangia production, and mycelia' growth were significantly reduced in the presence of STTC Results of laboratory tests suggest that application of S7TC as a soil drench could reduce inoculum production and subsequent new infections by P. citrophthora and P. parasitica.
Distribution of Two Species of Phytophthora Within the Citrus Acreage in ArizonaPkvtophthora citrophthora and P. parasitica cause gummosis and root rot of citrus trees in Arizona. A disease survey was initiated to determine the relative distribution of each pathogen within the citrus acreage of Maricopa and Yuma Counties. Both pathogens were recovered at the same time from 75% and 17% of orchards containing Phytophthora in Maricopa and Yuma County, respectively. P. citrophthora alone was found in 15% of the groves containing Phytophthora in Yuma County, while P. parasitica alone was detected in 25% and 68% of the citrus plantings containing Phytophthora in Maricopa and Yuma County, respectively. This survey will be continued for another year. The potential value of this information for improved disease control is discussed.
Chemical Freeze Protection of Citrus 1987/1988Research has shown that the presence of ice-nucleation-active (INA) bacteria, such as Pseudomonas syringae and Erwinia herbicola, will result in ice formation several degrees centigrade higher than would otherwise occur. Seven possible chemical frost protectants were applied to Lisbon lemons of the Yuma Mesa Ag Center. Four replications of effectiveness of the materials were evaluated by determining tip bum and fruit damage following two subfreezing episodes in December 1987. There were no statistically significant differences between treatments under the conditions of this study.
Effects of Canopy Position on Quality, Photosynthesis and Mineral Nutrition of Four Citrus VarietiesQuality, leaf gas exchange and mineral content of fruit from internal be canopies were compared with those from extemal canopy positions in 4 citrus varieties: 'Kinnow' mandarin; 'Redblush' grapefruit; 'Valencia' orange; and 'Lisbon' lemon. Fruit weight, total juice per fruit, peel fresh and dry weight, and rind thickness of fruit from internal canopies of all 4 varieties were significantly higher compared with external fruit Mandarin, grapefruit, and orange fruit from external canopies had higher soluble solids and specific gravity. Leaves from internal canopy had higher photosynthesis than those of external canopy in all varieties. Fruit from internal canopies of all varieties had generally higher peel concentrations (%dry weight) of N, P and K due to a dilution effect, while the opposite condition existed in mandarin when these elements were expressed on a percent fresh weight basis. Peel Mg and S from external fruit were higher in all varieties, expressed as percentages of either dry weight or fresh weight. Nitrogen content of mandarin and orange juice and calcium content of grapefruit and lemon juice from external fruit were significantly higher, compared to those from internal canopy fruit. Eliminating fruit quality and mineral variations resulting from canopy positions is recommended by the means of cultural practices.
The Effects of Navel Orange Prorate Suspension on F. O. B. to Retail Price SpreadsThe effects of the navel orange prorate suspension on packinghouse to retail price spreads are analyzed When compared with price spreads for the 1986 season, F.o.b.-retail price spreads declined for Atlanta and San Francisco, but increased for Dallas.