22 Feb 2024
Citrus Fruit Variety

Increasing fruit size in Citrus. Thinning and stimulation of fruit growth

The importance of fruit size as a parameter of quality of citrus fruits has increased markedly in recent times. The consumer’s marked preference for large fruit causes huge differences in price between large and small fruit to the point that the income from the smaller fruit is often less than picking and hauling costs. Fruit size has become as important as yield in the determination of the profitability of citrus plantings, and an economic premium is usually obtained through the increase in fruit size even at the expense of a reduction in crop yield. This applies not only to the small fruited mandarins and hybrids but also to large fruit species such as lemons, oranges and grapefruit. To increase fruit size beyond the limits which may be obtained through the optimization of the standard cultural practices (fertilization, irrigation, pruning), several techniques have been tried such as hand thinning [80], chemical and hormone thinning [49, 77] and the hormonal  stimulation of fruit growth rate by synthetic auxins [69, 70, 71]. The earlier investigations on this subject were reviewed extensively by Coggins and Hield [12], Monselise [57] and Wilson
[78], which pointed out some drawbacks encountered with the use of these techniques in practice. Particularly, the application of synthetic auxins to increase fruit size often resulted in too erratic results to justify the use of these compounds by the growers [57].

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25 Jan 2024
grapefruit

Influence of deficit irrigation timing on the fruit quality of grapefruit (Citrus paradisi Mac.)

The irrigation necessities for grapefruit production are very high. Due to the scarcity of water resources, growers use deficit irrigation (DI) – which could affect the fruit quality. Different DI strategies were studied: Control (irrigated at 100% ETc) and T1, T2 and T3 (50% ETc at phases I, II and III of fruit growth, respectively). Strategy T1 only delayed external maturation depending on the duration of the water stress. High water stress in T2 delayed fruit maturation, increased acidity and reduced the sugar concentration.

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25 Jan 2024
Washington Navel Orange

Effect of GA3 and Potassium Nitrate in Different Dates on Fruit Set, Yield and Splitting of Washington Navel Orange

Two concentrations of GA3 were used alone or with 0.5% urea i.e. (50 and 100 ppm) and three levels of potassium nitrate (KNO3) 2 ،4 and 6% were tested as foliar sprays at different times i.e. first time application at full bloom stage , the second time application was at fruit diameter from 1.5-2.0 cm and (first and second time of application) for investigation their effects on fruit set, yield, fruit quality and splitting of 40-years-old Washington navel orange (Citrus Sinensis), trees budded on Sour Orange (Citrus aurantium, L.Osbeck) rootstock during 2008 and 2009 seasons. Data indicated that, all treatments increased fruit set, yield and fruit quality and decreased fruit splitting as compared with control treatment. Data also revealed that, foliar sprays of trees by (GA3 at 50 ppm) with or without 0.5% urea were superior for inducing the highest increase of fruit set and yield, in addition KNO3 at 4% comparing with 2% and 6%. Also, KNO3 treatments increased fruit size, peel thickness and juice acidity especially with high concentrations; on the other hand, the use of GA3 at 50 or 100 ppm alone or with 0.5% urea increased fruit T.S.S and reduced nitrite and nitrate contents in fruit juice as compared with KNO3 treatments. Moreover, it is noticed that trees sprayed at first application or first and second time of application gave the best results, while second application was the best for reducing fruit splitting.

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25 Jan 2024

A Cost-Benefit Analysis for Crop Load

Generating profits in difficult conditions is one of the key drivers for sustainability in agriculture.

In recent years, some citrus producers have struggled to realise good returns as the industry faced a plethora of challenges. These challenges include, but are not limited to the cost of fertiliser, chemical, and fuel that rose rapidly because of the invasion of Ukraine, record freight rates and a decline in market prices.

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25 Jan 2024
Citrus Pruning in the Mediterranean

Citrus Pruning in the Mediterranean Climate: A Review

Pruning is a common practice in citrus for various reasons. These include controlling and shaping the canopy; improving phytosanitary health, productivity, and fruit quality; and facilitating operations such as harvesting and phytosanitary treatments. Because pruning is an expensive operation, its need is sometimes questioned.

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25 Jan 2024
Mealy Bug

Extension briefs for December and January 2024

Integrated pest management. False codling moth (S.D. Moore). It is utterly imperative that the False Codling Moth Management System (FMS) for citrus, including the False Codling Moth (FCM) Systems Approach, be implemented diligently and thoroughly. Neither growers nor the industry can afford a lapse in the implementation of comprehensive and effective management practices. The details of all of these practices are described in the FMS, with reference to CRI’s IPM Guidelines for FCM Management (available on the CRI website). These Good Agricultural Practices (GAPs) must be followed as described.

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25 Nov 2023
Valencia Orange

Effects of 3,5,6–trichloro-2-pyridyloxyacetic acid on fruit size and yield of Valencia Oranges

The Valencia orange is a high quality fruit grown in Turkey; however, small fruit size resulting in poor packouts is common in Valencia oranges. Small fruit size is the main factor limiting the marketing of Valencia oranges; thus, synthetic auxins are commonly used to enhance the size of citrus fruit. The objective of the present study was to observe the effects of 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6-TPA) on fruit size, yield and quality of Valencia oranges from 29-year-old trees budded on sour orange rootstock in Adana, Turkey in 2006. The application of 3,5,6-TPA to the entire tree was from 8th to 11th week after anthesis during June drop (JD). Following 3,5,6-TPA treatments, different combinations were used in the experiment: T1 2 tablets per 100 litres applied just after the end of June drop (JD), T2 2 tablets per 100 litres applied 5-7 days after the end of JD, T3 3 tablets per 100 litres applied 5-7 days after the end of JD, T4 4 tablets per 100 litres applied 5-7 days after the end of JD, T5 3 tablets per 100 litres applied 10-14 days after the end of JD and control trees receiving no 3,5,6-TPA (T0).

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25 Nov 2023
Summer pruning of Orange Trees

Summer Pruning of Orange Trees

Based on experience in West China, physiological responses to pruning of orange trees are quite different from apples. While winter pruning in suitable but not excessive amounts stimulates the vegetative processes of apples, it enhances the reproductive processes of citrus and summer pruning does the opposite. As a supplementary practice to winter pruning, summer pruning of oranges at the right time with specific techniques will invigorate neglected and old trees and modify the alter nate bearing habit of healthy trees. During the on-year, trees respond to moderate summer pruning by producing moderate amounts of summer flushes which increases the shedding of young fruits. Thus, the on-year crop will be reduced and the next year crop increased. This is “physiological thinning/’ as compared to chemical or hand thinning. Excessive summer pruning before the time of “June drop” can result in considerable fruit drop.

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