scholarly journals Citrus dwarfing viroid reduces canopy volume by affecting shoot apical growth of navel orange trees grown on trifoliate orange rootstock

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
I Lavagi-Craddock ◽  
R Campos ◽  
D Pagliaccia ◽  
T Kapaun ◽  
C Lovatt ◽  
...  
Keyword(s):  
Apical Growth ◽  
Navel Orange ◽  
Trifoliate Orange ◽  
Canopy Volume ◽  
Orange Trees

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

scholarly journals Citrus Viroids: Symptom Expression and Performance of Washington Navel Sweet Orange Trees Grafted on Carrizo Citrange

Plant Disease ◽  
2015 ◽  
Vol 99 (1) ◽  
pp. 125-136 ◽  
Author(s):  
N. Murcia ◽  
S. M. Bani Hashemian ◽  
P. Serra ◽  
J. A. Pina ◽  
N. Duran-Vila
Keyword(s):  
Sweet Orange ◽  
Fruit Production ◽  
Symptom Expression ◽  
Trifoliate Orange ◽  
Carrizo Citrange ◽  
Hop Stunt Viroid ◽  
Washington Navel ◽  
Canopy Volume ◽  
Viroid Infection ◽  
Orange Trees

Citrus are natural hosts of several viroid species. Citrus exocortis viroid (CEVd) and Hop stunt viroid (HSVd) are the causal agents of two well-known diseases of citrus, exocortis and cachexia. Other viroids have been found to induce specific symptoms and different degrees of stunting in trees grafted on trifoliate orange and trifoliate orange hybrids. A field assay was initiated in 1989 to establish the effect of CEVd, HSVd, Citrus bent leaf viroid (CBLVd), Citrus dwarfing viroid (CDVd), and Citrus bark cracking viroid (CBCVd) on Washington navel sweet orange trees grafted on Carrizo citrange rootstock. Here we report the effect of viroid infection on symptom expression, tree size, fruit production and quality evaluated from 2004 to 2007. Vegetative growth was affected by viroid infection with height and canopy volume being reduced. No bark scaling symptoms were observed in CEVd-infected trees albeit they presented lesions and blisters in the roots. Bark cracking symptoms were consistently observed in CBCVd-infected trees that were smaller with enhanced productivity and fruit size. No major effects were found as a result of infection with CBLVd, HSVd, or CDVd. The quality of the fruits was not affected by viroid infection, except for the low diameter of the fruits harvested from HSVd-infected trees. An interesting effect was identified in terms of tree productivity increase (yield/canopy volume) as a result of infection with CEVd, CDVd, and especially CBCVd.

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.

Influence of rootstocks on Navel orange yield and tree growth at Mildura, Victoria

1972 ◽  
Vol 12 (55) ◽  
pp. 203 ◽  
Author(s):  
LM Stafford
Keyword(s):  
Fruit Quality ◽  
Tree Growth ◽  
Soil Type ◽  
Sweet Orange ◽  
Tree Size ◽  
Irrigation District ◽  
Navel Orange ◽  
Trifoliate Orange ◽  
Rough Lemon

Two experiments with Navel orange scions (CV. Washington and Leng) on a number of rootstocks were done on three sandy Mallee soils in the Mildura irrigation district. Rootstocks included sweet orange (eight cultivars), rough lemon, mandarin (two cultivars), trifoliate orange, and citrange (two cultivars). In experiment 1 (1949 to 1963) eight sweet orange rootstocks gave similar results in terms of yield and tree size. Leng produced more but smaller fruit than Washington, but total weights were similar. In experiment 2 (1959 to 1969 and continuing) Leng trees were larger, produced more fruit, and on one soil a greater weight of fruit per tree than Washington. Sweet orange rootstocks were usually superior to other rootstocks on each soil type, although rough lemon gave results that were similar and, for a few combinations, superior. Trees on mandarin rootstocks were low producers and small in the early part of the experiment, but by the end of the period were yielding as much fruit as those on sweet orange. Trifoliate rootstocks were unsatisfactory, and citrange intermediate between sweet orange and trifoliate. No fruit quality differences ascribable to rootstock were detected.

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.

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