scholarly journals Fruit load and canopy shading affect leaf characteristics and net gas exchange of 'Spring' navel orange trees

2003 ◽  
Vol 23 (13) ◽  
pp. 899-906 ◽  
Author(s):  
J. P. Syvertsen ◽  
C. Goni ◽  
A. Otero
Keyword(s):  
Gas Exchange ◽  
Navel Orange ◽  
Leaf Characteristics ◽  
Orange Trees ◽  
Fruit Load

Effect of transmission of exocortis dwarfing factors into Washington navel orange trees

1975 ◽  
Vol 15 (72) ◽  
pp. 136 ◽  
Author(s):  
MC Stannard ◽  
JC Evans ◽  
JK Long
Keyword(s):  
High Density ◽  
Normal Density ◽  
Navel Orange ◽  
Trifoliate Orange ◽  
Four Seasons ◽  
Washington Navel ◽  
Area Basis ◽  
Early Production ◽  
Orange Trees

Washington navel orange trees on trifoliate orange rootstocks were inoculated at various ages with budwood from either severely dwarfed Washington navel trees with butt scaling caused by exocortis virus or moderately dwarfed Marsh grapefruit trees with no butt scaling. Dwarfing, measured by trunk girth, became apparent four seasons after inoculation, the butt scaling inoculum causing more pronounced dwarfing than the non-scaling inoculum. For both inocula, trees inoculated in the nursery were the most dwarfed, and yielded least, with trees inoculated in the field one, two, three or five years later being successively less dwarfed and high yielding. In a second experiment, Washington navel orange trees on trifoliate orange, which were carrying exocortis virus or were inoculated with it either in the nursery or later in the field, were planted in 1962 at a density of 835 ha-1. The field inoculated trees subsequently grew larger than the others. All were more dwarfed but yielded more heavily on a ground area basis during five years of cropping than exocortis-free trees planted at a normal density of 222 ha-1. Dwarfed trees developed butt scaling symptoms and periodically became unthrifty. The non-scaling form of dwarfing lends itself to the development of high density plantings of small trees with consequent benefits in management and high early production

Possible Methods to Increase Efficacy of Gibberellic Acid Applied to Navel Orange Trees

2018 ◽  
pp. 567-572
Author(s):  
Charles W. Coggins ◽  
Gilbert L. Henning ◽  
Michael F. Anthony
Keyword(s):  
Gibberellic Acid ◽  
Navel Orange ◽  
Orange Trees

scholarly journals EFFECT OF ENRICHED COMPOST TEA ON WASHINGTON NAVEL ORANGE TREES

2009 ◽  
Vol 34 (10) ◽  
pp. 10085-10094
Author(s):  
M. Mostafa ◽  
M. El-Boray ◽  
A. Abd El-Wahab ◽  
R. Barakat
Keyword(s):  
Navel Orange ◽  
Compost Tea ◽  
Washington Navel ◽  
Orange Trees

scholarly journals Evaluation of New Oomycota Fungicides for Management of Phytophthora Root Rot of Citrus in California

Plant Disease ◽  
2019 ◽  
Vol 103 (4) ◽  
pp. 619-628 ◽  
Author(s):  
Wei Hao ◽  
Morgan A. Gray ◽  
Helga Förster ◽  
James E. Adaskaveg
Keyword(s):  
Root Rot ◽  
Treatment Options ◽  
Management Strategies ◽  
Resistance Management ◽  
Tree Canopy ◽  
Navel Orange ◽  
Phytophthora Root Rot ◽  
Trunk Diameter ◽  
New Compounds ◽  
Orange Trees

Phytophthora root rot, caused by several species of Phytophthora, is an important disease of citrus in California and other growing regions. For chemical management, mefenoxam and potassium phosphite have been available for many years, and resistance in Phytophthora spp. has been reported for both compounds. We evaluated the efficacy of the new Oomycota fungicides ethaboxam, fluopicolide, mandipropamid, and oxathiapiprolin, each with a different mode of action, against Phytophthora root rot of citrus in field and greenhouse studies. Root balls of navel orange trees on ‘Carrizo citrange’ rootstock were inoculated with P. nicotianae at planting in the field in fall 2013. Applications with 11 fungicide treatments were made 5 weeks after planting, in spring and fall 2014, and in spring 2015. Feeder roots and adjacent soil were collected before or after application. All of the new fungicides significantly reduced root rot incidence and Phytophthora soil populations to very low levels as compared with the control starting after the first application. Mefenoxam was only effective when a high label rate was used in the fourth application. Selected treatments also increased tree canopy size, trunk diameter, and fruit yield as compared with the control. A rate comparison with the four new fungicides was initiated in summer 2016 in another field trial using navel orange trees inoculated with P. citrophthora. Minimum effective rates to reduce Phytophthora root rot incidence and pathogen soil populations were determined after one and two applications in fall 2016 and summer 2017, respectively. Greenhouse studies confirmed the efficacy of the new fungicides. Based in part on our studies, fluopicolide recently received a federal and oxathiapiprolin a full registration for use on citrus, and registrations for ethaboxam and mandipropamid have been requested. These new compounds will provide highly effective treatment options and resistance management strategies using rotation and mixture programs for the control of Phytophthora root rot of citrus.

scholarly journals Citrus Cutworm Pesticide Efficacy Trials, 1994

1995 ◽  
Vol 20 (1) ◽  
pp. 57-57
Author(s):  
E. E. Grafton-Cardwell ◽  
C. A. Reagan
Keyword(s):  
Honey Bees ◽  
Ground Level ◽  
Navel Orange ◽  
Above Ground Level ◽  
Sample Tree ◽  
Efficacy Trials ◽  
Washington Navel ◽  
Extension Center ◽  
Orange Trees ◽  
Detrimental Impact

Abstract Insecticides for the control of citrus cutworm were evaluated on 29 yr old ‘Washington navel’ orange trees at the Lindcove Research and Extension Center, Exeter, CA. The insecticide applications were made on 28-29 Apr with a Bean hand-sprayer at 450 psi and approximately 300 gpa (3—4 gal/tree). Lorsban was applied after sunset to reduce the detrimental impact of the insecticide on honey bees in the orchard. The 14 treatments were assigned based on pretreatment sampling of larvae and each of the treatments were applied to single trees, replicated 8 times. Larval collections were accomplished by placing a canvas beating sheet (112 cm × 75 cm) beneath the outside foliage of the tree and vigorously shaking the foliage 10 times. Citrus cutworm larvae which fell onto the canvas were counted and recorded by instar, then returned to the foliage. Pretreatment larval counts were made on 20 Apr by sampling the northeast and southwest quadrants of each tree. Post treatment counts were made on 9 May by sampling all four quadrants of each sample tree, again recording each instar. Percentage of scarred fruit due to citrus cutworm feeding was evaluated on 7 Sept on each of the sample trees within a 2 m vertical swath around the tree beginning approximately 20 cm above ground level and extending approximately 40 cm into the tree interior. In 1994, late Apr and early May temperatures at Lindcove ranged from relatively cool to warm, with daily maximums between 61°F and 90°F (mean of 72.5°F).

scholarly journals Citrus Red Mite Pesticide Efficacy Trials, 1995, 1996

1997 ◽  
Vol 22 (1) ◽  
pp. 69-70
Author(s):  
E. E. Grafton-Cardwell ◽  
C. A. Reagan
Keyword(s):  
Predatory Mites ◽  
Predatory Mite ◽  
San Joaquin Valley ◽  
Navel Orange ◽  
Citrus Red Mite ◽  
Single Tree ◽  
Efficacy Trials ◽  
Washington Navel ◽  
Extension Center ◽  
Orange Trees

Abstract Acaricides for control of citrus red mite were evaluated in the spring of 1995 and 1996 on ≈20 year old ‘Washington navel’ orange trees at the Lindcove Research and Extension Center, Exeter, CA. The acaricides were compared for efficacy against citrus red mite as well as their impact on populations of a predatory mite, which feeds on citrus red mite in San Joaquin Valley orchards. The acaricides were applied on 19 May in 1995; and on 8 Apr in 1996 using a Bean hand-sprayer at 300 psi and approximately 300 gpa (3^1 gal/tree). Single tree treatments were assigned based on pretreatment sampling of citrus red mite conducted on 9 May 1995 and 7 Apr 1996. Samples consisted of five leaves from the periphery of four quadrants of each tree (20 leaves per tree). The number of all active stages of citrus red mite and predatory mites per leaf were recorded weekly.

TRAP DESIGNS FOR MONITORING EMERGENCE OF FRANKLINIELLA BISPINOSA (MORGAN) (THYSANOPTERA: THRIPIDAE) FROM SOIL IN CITRUS GROVES

1993 ◽  
Vol 125 (3) ◽  
pp. 449-456
Author(s):  
C.C. Childers
Keyword(s):  
Navel Orange ◽  
Citrus Grove ◽  
Shell Vial ◽  
Wooden Frame ◽  
Emergence Trap ◽  
Citrus Groves ◽  
Orange Trees ◽  
Trap Placement ◽  
Citrus Trees

AbstractThree emergence trap designs were evaluated for effectiveness in collecting adult Frankliniella bispinosa (Morgan) (Thysanoptera: Thripidae) from beneath and between citrus trees in Florida. Trap A [a wooden-frame 30- by 30-cm (= 900 cm2) square trap with removable Plexiglas® lid coated with Tangle-Trap® adhesive] was effective in trapping F. bispinosa adults whereas trap B [a polyvinylchloride (PVC) round trap with a centered 3.7-mL capacity shell vial] was ineffective. Trap A was as effective in collecting emerging F. bispinosa adults as trap C [a PVC round trap with a 30-cm-diameter (= 706.5 cm2) removable adhesive-coated Plexiglas lid]. Comparative costs for trap construction, maintenance, and insect counting are all higher for trap A compared with trap C. Trap placement beneath citrus trees 15 cm from the trunk or just inside the dripline of the canopy provided similar thrips catches in two citrus grove sites. Both interior and dripline trap positions beneath "navel" orange trees had significantly higher numbers of F. bispinosa than did traps exposed within rows between these trees.

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