Control of melanose, caused by the fungus Diaporthe citri, is often necessary in mature groves where fruit is intended for the fresh market, particularly if recently killed twigs and wood are present as a result of freezes or other causes. It is not usually necessary in groves less than 10 years old or those where fruit is intended for processing. Grapefruit is very susceptible to melanose but all citrus may be damaged by the disease.
Greasy spot is caused by the fungus Mycosphaerella citri. Management must be considered in groves intended for processing and fresh market fruit. Greasy spot is usually more severe on leaves of grapefruit, pineapples, Hamlins, and tangelos than on Valencias, Temples, Murcotts, and most tangerines and their hybrids.
In 2009/10, total citrus production is forecast at about 627,000 tons, a 10 percent increase compared to the previous year. Out of the total production, approximately 183,000 tons (29 percent) is expected to be exported, 260,000 processed (42 percent), and the remainder consumed fresh. The expected increase is mainly due to increased yields of Or variety (easy peeler) and red grapefruit.
Total citrus production is forecasted to increase to 1,562,600 MT in marketing year 2010/11. It is anticipated that the profile of citrus, in terms of consumption and trade, will also increase with the World Cup coming to South Africa in 2010.The success of a plum campaign in the United Kingdom using the tag line “Beautiful Country, Beautiful Fruit might also be used by the citrus stakeholders with the objective of raising the profile of South African citrus.
Post forecasts a decrease in fresh lemon production for CY 2010 to 1 million MT due to a severe drought and late frosts. Fresh orange production is expected to increase to 840,000 MT, and fresh tangerine production is estimated to rebound to 370,000 MT, as a result of good weather conditions. Fresh grapefruit production is projected to decrease slightly to 225,000 MT, as area planted to grapefruit is decreasing.
Management of brown rot, caused by Phytophthora nicotianae or P. palmivora, is needed on both processing and fresh market fruit. While the disease can affect all citrus types, it is usually most severe on Hamlin and other early maturing sweet orange cultivars.
Foot rot results from infection of the scion near the ground level, producing bark lesions which extend down to the budunion on resistant rootstocks. Crown rot results from infection of the bark below the soil line when susceptible rootstocks are used. Root rot occurs when the cortex of fibrous roots is infected, turns soft and appears water-soaked. Fibrous roots slough off their cortex leaving only a white thread-like stele (inner tissue of the fibrous root). Foot rot and root rot can be caused by P. nicotianae or P. palmivora.
At time of writing this report, drought and low prices for fresh oranges are constraining orange production in Australia. Despite recent rainfall and some improvement in the availability of irrigation water, overall water availability remains at historically low levels following years of drought. A stronger Australian dollar has kept export prices low, although industry sources believe that historically high retail prices for fresh juice have improved the outlook for oranges suitable for processing.