Observations on the Possibility of Producing Two Crops of Apples a Year in the Kenya Highlands

Abstract

Production of deciduous fruit trees in the Kenya highlands is heavily dependent on natural chilling to break bud rest; thus, fruit production follows the natural pattern of weather. In this mode of production, flowering occurs once every year, leading to the production of only one crop. Due to incomplete natural conditions and long periods of high solar radiation in the tropics, delayed defoliation is a major factor limiting fruit yields (Epenhuijsen, 1976; Denis, 1985; and Erez and Lavi, 1985). Dormancy-breaking chemicals, such as tar oil, winter wash, and nitrocellulose, are often used to enhance the effect of natural chilling to break bud rest (Ruck, 1975 and Lavi, 1985). However, the use of these chemicals by small-scale farmers in Kenya is limited because they are prohibitively expensive. Some cultural practices, such as defoliation, pruning, and other methods, have been reported to be effective substitutes for natural chilling (Ruck, 1975; Notodimedjo et al., 1981) and chemical treatment (Ruck, 1975) in overcoming dormancy and delayed foliation. In Indonesia, defoliation of apple trees soon after harvesting reportedly leads to bud break and flowering during the expected dormant season, thus allowing the production of more than one crop per year (Notodimedjo et al., 1981 and Verheij, 1985). Similarly, defoliation has been reported to overcome prolonged dormancy during the normal fruit season (Ruck, 1975).