Bloei en bloeislaging van de robusta koffie op Sumatra's Westkust

As an insight into flowering and fruit yield the percentage of flowers yielding fruits was estimated. To allow for variation between branches, many flowers must be taken. The extent of flowering of robusta coffee depended on the relation between vegetative and generative growth, both showing a maximum and a minimum, while factors favouring one were often adverse-for the other. The physiological condition of the trees strongly influenced fruit setting. Stephanoderes hampei F. may penetrate berries 3-5 months old. Consequently rotting and damage may lead to a considerable fall. This fall depended much on the condition of the tree and not on the number of S.hampei. Falling was also favoured by sunny and dry periods.
A good regular shading promoted flowering and fruit production, due mainly to a better water supply preventing yellowing and dying of the leaves. Too much shading may be harmful to the generative growth, so pruning must lead to more light during wetter months. For a better water supply the humus content of the soil could be improved. The percentage fruit set of primary, secondary, upper, medium and low branches showed that 'topping', preventing water shortage in dry periods, was not harmful for fruit set. Lower trees also facilitate the control of S.hampei and the harvesting.