Topping — pruning the tops of trees — along orchard edges has been studied as a potential strategy for managing citrus greening disease. This technique aims to stimulate new shoot growth on trees along the orchard perimeter to attract the psyllid — the insect vector responsible for transmitting the disease. Chemical control efforts can then be concentrated in those specific areas.
However, research results conducted by Brazil’s Fundecitrus and Embrapa indicate that this practice requires caution and should not be adopted in isolation.
The research was carried out over a three-year period in commercial orchards in the interior of São Paulo state. It demonstrated that topping can significantly increase the production of new shoots and, consequently, attract a greater number of psyllids to these areas. While this may facilitate the targeted application of pesticide sprays, the actual impact on greening incidence varies depending on the citrus variety. In trees of the Hamlin variety, for instance, an increase in disease incidence was observed in the pruned areas whenever vector control measures were not rigorously enforced.
In light of these findings, researchers emphasize that topping can indeed be incorporated into an orchard management program, provided it is integrated with other strategies. Those strategies include efficient chemical control, insecticide rotation and the removal of infected trees. Without this comprehensive set of actions, there is a risk that the practice of topping along orchard edges could actually heighten disease pressure rather than reduce it.
Source: Fundecitrus
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