Oil palm, a lucrative vegetable oil crop in the world, showed promising adaptability to some agroecologies in Uganda from studies carried out in the 1970s resulting in first commercial establishment in 2005 in Bugala Island, Kalangala district. Further, adaptability studies continue to reveal suitable areas for commercial oil palm production in the country. The infant industry faces an array of challenges, both biotic and abiotic especially in regard to smallholder farmer field management and build-up of pests and disease in the face of climate change both in the nuclear estate and smallholder farmers' fields.
The rapid build-up of devastating diseases such as Fusarium wilt of oil palm and Ganoderma trunk rot in Uganda is an interesting scenario since they are often expected from second-phase plantings in other areas in the world. However, it may be attributed to the all-year-round weather suitability to pests and disease build-up on native or alternative hosts in most agroecologies in Uganda. This difference from other oil palm producing regions in the world has resulted in recently initiated oil palm Research in Uganda to focus on developing local solutions to challenges facing oil palm farmers in the country.
Global-Palm-Oil-Market-Insights-Trends-Forecast. Asia (Indonesia, Malaysia and Thailand) is the largest producer, followed by Africa, Americas and Oceania. In Africa, oil palm is grown in 25 countries and is mainly supported by corporate investors (Carrere, 2013). Some countries have land area under natural oil palm stands in traditional plantations while others have oil palm land where negotiations are underway or already completed (Carrere, 2013). Nigeria has the largest area under natural oil palm stands/traditional plantations followed by Democratic Republic of Congo, Guinea and Togo. However, other countries like Angola, Burundi, Congo Republic, Equatorial Guinea, Ethiopia, Gabon, Gambia, Ghana, Guinea Bissau, Liberia, Madagascar, Mozambique, Sao Tome and Principe, Tanzania and Uganda do not have estimated figures of land under traditional oil palm cultivation or do not have any area under traditional oil palm cultivation but land is negotiated or being negotiated for large scale industrial production (Carrere, 2013)
In Uganda, Oil palm cultivation began in 2005 in Bugala islands. It was initiated by Vegetable oil development project (VODP) as an innovative public-private-producer-partnership (4P) approach based on a vertically integrated processor-nucleus estate smallholder mode (NOPP, 2017) and is in the process of being extended to other parts of the country including Masaka, Buvuma and Mayuge Districts. Adaptive trials are also conducted across the country in areas such as Bugiri, Kibaale and Kituza to test the environments for possible future expansion of commercial oil palm production. However, Uganda does not have a breeding program for oil palm. Therefore, improved oil palm varieties mostly hybrids are imported from South-East Asian countries, such as Malaysia and Indonesia and West African countries like the Ivory Coast and Ghana
The Fresh Fruit Bunches (FFBs)are processed into Crude Palm Oil (CPO) by Oil Palm Uganda Limited (OPUL) and the company has effective Quality Management Systems (QMS) in place to make sure quality CPO is produced. Optimum harvesting cycle time and optimum minimum ripeness standards are normally established to ensure maximum oil content and acceptable levels of free fatty acid (FFA) in FFBs are maintained. However, these standards are based on the country from which the seedlings are imported, yet the environmental conditions in Uganda are quite different from the countries where breeding programs are established. During the time of harvesting, in adaptive trials and different smallholder farmer blocks, several physiological disorders like bunch failure, bunch rot and un-even ripening have been reported (NOPP, 2017). These disorders cause high losses in yield worldwide, which culminate in great economic loss to oil palm industries including those in Uganda.
Bunch failure may be caused by some herbicides, 'overbearing' and poor pollination (Corley and Tinker, 2016). The incidence of bunch rot is unknown in Uganda. Two fungal species have been identified in causing bunch rot disease namely, Marasmius palmivorus and Corticium rolfsii with the former being the most destructive (Verheye, 2010). Marasmius palmivorus is primarily saprophytic on decaying organic matter. It becomes pathogenic in the presence of a large mass of dead or decaying organic matter. The threshold amount of inoculum necessary to cause disease is however not known and according to Aderungboye (1997), the disease is common under poor natural pollination. It begins as white strands of the mycelium covering the bunch surface which later penetrate the pericarp of the fruits causing wet rot of fruits
Affected fruits become soft then turn brown and black in color before rotting and drying off. Yield loss is both direct through the rotting of bunches and indirect due to quality deterioration. Quality loss results from increased free fatty acid content of the fruits following infection and untimely harvesting. Improving sanitation, ablation, assisted pollination and fungicide application have been reported to reduce the adverse effects of this disease (Chung, 2011). Information on the occurrence of this disease in oil palm in Uganda is scanty. Such information is critical for the effective management of the bunch rot disease. Similarly, uneven ripening resulting from an imbalance in dry matter allocations because bunch sink requirements strongly increase in the last phase towards ripening as reported by Henson et al. (2008) is also well pronounced in oil palm farms in Uganda.
This results in the harvesting of half-ripe bunches which leads to poor fresh fruit bunch quality and high free fatty acid levels affecting oil palm profitability due to the rejection of poor-quality fruits at the factory (Woittiez et al., 2017). Bunch failure is also believed to be caused by poor natural pollination (Aderungboye, 1997) among other causes. However, like bunch rot and uneven ripening, the incidence level of bunch failure in Uganda is also not known and this curtails management options. Therefore, the aim of the study was to determine the incidence of uneven ripening, bunch failure and bunch rot and its severity as common physiological disorders on oil palm fruits so that effective management options can be sought and policy.
