21 Jul 2022
Valencia oranges

South Africa to appeal against new EU citrus rules

CGA’s Justin Chadwick said cold treatment requirement is unnecessary, unjustified and disproportionate.

The South African citrus industry is scrambling to avert disruptions in its citrus exports to the European Union due to changes in regulations governing the importation of oranges into the EU.

The new regulations, which deal specifically with orange imports from South Africa and other sub-Saharan countries, were published in the Official Journal of the European Union on Tuesday and will come into force today.

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21 Jul 2022
Navel Pickers

South African citrus: “The Russian market turned out to be actually very good”

Running a fruit exporting company feels a bit like being an operational company that happens to sell fruit at the moment, an exporter remarks, when managing logistics and fighting for space and equipment on vessels take up most of their days.

“You have to be passionate about fruit to be working in the fruit trade,” he says. “It’s not an easy place at the moment.”

Slow colour development on Valencias in Limpopo Province has meant at least two to three weeks of lost marketing opportunities, which, along with impediments to South Africa’s lemon and the grapefruit harvest, could explain why citrus volumes via Durban port have, thus far, not been as high as expected.

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21 Jul 2022
Leaf Abscission

Abscisic Acid Reduces Leaf Abscission and Increases Salt Tolerance in Citrus Plants

This paper describes the physiological effects of abscisic acid (ABA) and 100 mM NaCl on citrus plants. Water potential, leaf abscission, ethylene production, photosynthetic rate, stomatal conductance, and chloride accumulation in roots and leaves were measured in plants of Salustiana scion [Citrus sinensis (L) Osbeck] grafted onto Carrizo citrange (Citrus sinensis [L.] Osbeck · Poncirus trifoliata [L.] Raf) rootstock. Plants under salt stress accumulated high amounts of chloride, increased ethylene production, and induced leaf abscission. Stomatal conductance and photosynthetic rates rapidly dropped after salinization.

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23 Jun 2022
Valencia

Effect of Different Rates of Sulphur Fertilization on Fruit Yield and Leaf Mineral Composition of ‘Valencia’ Oranges in the Subtropical Environment of South Africa

Although sulphur is one of the essential nutrients for plant growth with a crop requirement similar to phosphorus (P), this nutrient element has received little attention because it is supplied in insecticides, fungicides, manure and from the atmosphere. With the relaxation of this requirement, and restrictions on sulphur dioxide emissions by industries it has become apparent that sulphur deficiency is widespread throughout the world. The majority of farmers submitting samples for soil and leaf nutrient analysis do not request a sulphur (S) test. This is due to the fact that farmers are still under the impression that there is enough sulphur in the soil.

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23 Jun 2022
Foliar Fertilizer

Properly Timing Foliar-applied Fertilizers Increases Efficacy: A Review and Update on Timing Foliar Nutrient Applications to Citrus and Avocado

Foliar fertilization efficiently meets the nutrient demand of tree fruit crops during periods when soil conditions (low or high temperatures, low or excess soil moisture, pH, salinity) render soil-applied fertilizers ineffective, when nutrients (e.g., phosphate, potassium, and trace elements) become fixed in the soil, and when tree nutrient demand is high. Applying nutrients directly to leaves ensures that the metabolic machinery of the tree is not compromised by low availability of an essential nutrient. It should be noted that phloem mobile nutrients applied to the foliage are translocated to all tree parts, even feeder roots.

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25 May 2022
EU Flag

New proposed EU regulations threaten the export of Southern African oranges to the region

This week, the European Union’s (EU) Standing Committee on Plant, Animal, Food and Feed (SCOPAFF) will discuss and, possibly vote on, new and arguably misinformed regulations on False Coddling Moth (FCM) which pose a major threat to Southern African orange exports.

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25 May 2022
Orange Blossom

Influence of Temperature and Photoperiod on Flower Induction and Inflorescence Development in Sweet Orange.

At low temperature (15° C.day/5° C.night) flowering of sweet orange cuttings was not photoperiodically controlled, occurring at 16-, 12-, and 8-hour photoperiods. When plants were transferred, after varying periods of low temperature (15°/8° C.) to warm conditions (30°/25° C.), growth of the buds commenced within a few days of transfer. Flowering response to length of the cold treatment appeared to be quantitative.

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25 May 2022
Citrus Tree Stresses

Citrus Tree Stresses: Effects on Growth and Yield

Although Florida is known for its plentiful sunshine and rainfall, commercial citrus can experience stress at certain times of the year whenever growth conditions are not optimal. For example, drought stress can occur whenever soil water is not adequate or whenever the evaporative demand of the air is high. Drought is one of the most formidable stresses. It alters a tree’s ability to take up nutrients from soil and changes the way the tree produces roots, shoots, leaves and fruit. To strive for consistently high commercial yields, grove managers must incorporate strategies to minimize the negative effects of drought.

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25 May 2022
Young Clementine

Seasonal Fe Uptake of Young Citrus Trees and Its Contribution to the Development of New Organs

This work quantifies Fe uptake in young citrus trees, its partitioning among plant compartments, and the contribution of the Fe absorbed from fertilizer to the development of new tissues. A soil pot experiment was conducted using 4-year-old clementine trees (Citrus clementina Hort ex Tan), and a dose of 240 mg Fe was applied by labeled fertilizer (92% atom 57Fe excess). Plants were uprooted at five different phenologic states: end of flowering (May 15), end of fruit setting and fruit drop (July 1), two fruit growing moments (August 1 and October 15), and at complete fruit maturity (December 10). The Fe accumulated in the root system exceeded 90% of the total Fe content in the plant. All organs progressively enriched with 57Fe (8.5–15.5% and 7.4–9.9% for young and old organs, respectively). Reproductive ones reached the highest increase (111% between May and October). 57Fe enrichment from woody organs reflects an increasing gradient to sink organs.

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25 May 2022
Carotenoid Biosynthesis

Carotenoid Biosynthesis and their Regulation in Citrus Fruits

Carotenoids are the main pigments responsible for the attractive color of the peel and pulp of citrus fruits and greatly contribute to their nutritional and antioxidant value. Fruits of different Citrus species display a broad array of color singularities and in many cultivars the peel and the pulp also exhibit different color, envisaging specie- and tissue- specific regulation of the carotenoid content and composition.

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