Re-Fining Citrus Leaf and Fruit Spot Disease Control Options in Northern Uganda

Abstract

Citrus leaf and fruit spot disease, caused by Pseudocercospora angolensis has, since 2010, come about as the most dreadful disease of citrus in Northern Uganda. Over the last few years, feedback from citrus farmers has helped in re-fining management strategies. In the first years of citrus leaf and fruit spot disease outbreak in Northern Uganda, chemical treatment was promoted as part of a control package, in addition to the destruction of heavily diseased plants and buckthorn to remove inoculum. Buck horning and destruction of diseased plants is labour-intensive and time-consuming, especially when many infected citrus trees have to be taken out, or buck horned. Research findings indicate citrus leaf and fruit spot disease fungus can be weakened with fungicide sprays to the extent that even when disease symptoms are present on leaves, it does not automatically lead to infection of fruits. This gave rise to a new control strategy where only infected plants in an orchard are pruned, and all the citrus trees in the orchard are treated with fungicides. The pruning of visibly infected plants in an orchard will lessen the inoculum load, and the fungicide sprays will stop pathogen replication. This method is not labour intensive and takes less time when equated to severe buck horning of all the trees in the orchard. However, pruning and fungicide treatment need to move together with the control of new infections that can happen via unrestricted entry during harvesting