A synthesis of Hass avocado agronomy and pests management
Odong, Piero Corti
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In response to the enormous market especially from Western Europe, farmers in Uganda have embarked on Hass avocado production to tap into this market. However, there is limited information available to guide the farmers on good agronomic practices and pest management, which are key to increasing Hass avocado yields and production. The purpose of this study was to consolidate available information scattered in various sources about water, nutrients and pest management in Hass avocado and to stream line the units and formats of reporting in a user-friendly manner for practitioners. Since no information could be found about Hass avocado agronomy in Uganda, attention was shifted to available information about water , nutrients and pest management in major Hass avocado growing countries and regions within the Tropics such as Mexico, Colombia, Brazil, South Africa, Kenya, Ethiopia, and elsewhere, where the information could be accessed. Peer-reviewed articles and other sources of literature accessed indicated that authors reported results about water and nutrient requirements of Hass avocado in different formats and units requiring some basic scientific background to be able to interpret, which could confuse potential beneficiaries of the information. Wherever such confusion was encountered, the results reported were recalculated and findings reported in standardized formats and SI units in a simplified format for practitioners. Appropriate conversions were also made wherever found necessary to standardize quantities of water, nutrients required as well as Hass avocado yields per unit area. The average amount of rainfall received in the different Hass avocado producing regions of the world range from 899 – 1312 mm per annum with daily irrigation requirements ranging from 1.5 mm (15m3/ha) in winter (South Africa) to 6 mm (60 m3/ha) during summer in California. The overall yield of avocado trees per hectare of land generally increases with increase in applied irrigation. Nutrients required at planting are P, Mg, Mn, Cu, Zn and good quality FYM but not N and K. For example, during seedling establishment, Phosphorous (P) is the most needed nutrient at a rate of 45g per hole, followed by magnesium (Mg) at16g per hole, zinc (Zn) at 12.25g per hole, Manganese (Mn) 11g per hole and Copper (Cu) at 6g per hole. The overall requirement of the different nutrients by avocado trees generally increases as the age (1 – 15+ years) of the tree also increase. For example, Nitrogen (N) requirements increase from 5.2 kg/ha at 1 year to 53.9 kg/ha at 15 years and above, Phosphorous (P) from 6.0 kg/ha to 31.8 kg/ha, Potassium (K) at 17.6 kg/ha in the 6th year to 50.7 kg/ha at 15+ years. Farm Yard manure (FYM) requirements also increase with the age of the tree i.e. 2340 kg/ha at 1 year to 4680 kg/ha at 7 years. The nutrients are especially required at critical stages such as towards flowering and after harvest especially during a heavy year. Scales and thrips are the two major Hass avocado pests that have been reported in both Kenya and Australia unlike false codling (Thaumatotibia leucotreta) moth and fruit flies (Bactrocera dorsalis) that have only been reported in Kenya with conserving natural enemies and Spray if soft chemicals being the major recommended control methods. Phytopthora root rot is the most widely spread and most devastating disease affecting Hass avocado followed by Anthracnose, cercospora and verticillium wilt with cultural and chemical control practices still remaining the dominant practices in the major avocado growing countries across the world as reported in USA(California), Kenya and Australia. Countries, which are using rain fed Hass avocado production could exponentially increase their Hass avocado yields by providing supplemental irrigation in addition to synchronized nutrient application especially during dry season and at the critical stages of growth of the tree and proper pest management.