scholarly journals Response of Washington Navel Orange Trees to Calcium Chloride Foliar Application

2015 ◽  
Vol 42 (Issue 1) ◽  
pp. 169-179
1994 ◽  
Vol 119 (6) ◽  
pp. 1144-1150 ◽  
Author(s):  
Anwar G. Ali ◽  
Carol J. Lovatt

The objective of this study was to test whether a single winter prebloom foliar application of low-biuret urea would increase the yield of 30-year-old `Washington' navel orange trees [Citrus sinensis (L.) Osbeck] on Troyer citrange rootstock [C. sinensis `Washington' × Poncirus trifoliata (L.) Raf.]. All trees received a winter (November to January) soil application of urea (0.5 kg N/tree). Trees were maintained under irrigation or irrigation was withheld from 1 Oct. to 1 Mar. To determine the optimal time for foliar urea application, trees in both irrigation main plots received one application of low-biuret urea in mid-November, mid-December, mid-January, or mid-February applied at a rate of 0.16 kg N/tree. There was a set of control trees that only received the soil application of urea. Trees receiving foliar-applied urea in mid-January or mid-February, independent of irrigation treatment, had significantly greater yield and fruit number per tree each year than the control trees for 3 consecutive years. The number of fruit with diameters of 6.1 to 8.0 cm increased significantly as yield increased (r2 = 0.88). Withholding irrigation from 1 Oct. to 1 Mar. had a negative impact on yield. Annual winter application of low-biuret urea to the foliage did not significantly increase leaf total N at the end of 3 years.


2016 ◽  
Vol 10 (7) ◽  
pp. 59-69 ◽  
Author(s):  
Hussien Hanafy Ahmed Ahmed ◽  
Ramadan Aboul-Ella Nesiem Mohamed ◽  
Ali Allam Hesham ◽  
Fahmy El-Wakil Amira

Horticulturae ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 233
Author(s):  
Sherif Fathy El-Gioushy ◽  
Rokayya Sami ◽  
Amina A. M. Al-Mushhin ◽  
Hanan M. Abou El-Ghit ◽  
Mohamed S. Gawish ◽  
...  

The goal of this study was to examine how to improve the vegetative growth, nutritional status, productivity, and fruit quality of Washington navel orange trees by examining the effect of foliar application of ZnSO4 (0, 300, and 600 mg/L) solutions in combination with CuSO4 (0, 200, and 400 mg/L) solutions on Washington navel orange trees, which were 11 years old and grown in clay loam soil with a surface irrigation system. The results showed that all the investigated measurements responded specifically to each investigated factor. ZnSO4 elicited a stronger and more effective response than CuSO4. Nonetheless, the response varied only slightly or moderately from one measurement to the next. In terms of the interaction effect between ZnSO4 and CuSO4 concentrations, the effect of each investigated factor was directly reflected in its combinations, with ZnSO4 (600 mg/L) and CuSO4 (200 and 400 mg/L) being the most effective for the majority of the measurements under consideration. When the highest level of ZnSO4 was combined with the highest level of CuSO4, the highest values for the various vegetative growth parameters shoot length and diameter, number of leaves per shoot, leaf area, and total assimilation area per shoot were obtained. As a result, the nutritional status (the highest total leaf chlorophyll and leaf mineral contents) was significantly coupled with the treatment of 600 mg/L ZnSO4 in combination with 400 mg/L CuSO4. Moreover, the combinations of the highest ZnSO4 concentration (600 mg/L) and CuSO4 concentration (400 mg/L) exhibited the greatest statistical values of the measurements of fruiting aspects as well as fruit quality. Consequently, it can be recommended that using 600 mg/L ZnSO4 in combination with 400 mg/L CuSO4 as a foliar spray on monthly basis during the period from March to July could be safely recommended under similar environmental conditions and horticulture practices adopted in the present experiment.


1975 ◽  
Vol 15 (72) ◽  
pp. 136 ◽  
Author(s):  
MC Stannard ◽  
JC Evans ◽  
JK Long

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


2009 ◽  
Vol 34 (10) ◽  
pp. 10085-10094
Author(s):  
M. Mostafa ◽  
M. El-Boray ◽  
A. Abd El-Wahab ◽  
R. Barakat

1995 ◽  
Vol 20 (1) ◽  
pp. 57-57
Author(s):  
E. E. Grafton-Cardwell ◽  
C. A. Reagan

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).


1997 ◽  
Vol 22 (1) ◽  
pp. 69-70
Author(s):  
E. E. Grafton-Cardwell ◽  
C. A. Reagan

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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