Fundecitrus recently issued recommendations for leprosis management in Brazil. Leprosis has been expanding in the Brazilian citrus belt for the last six years and is an increasingly significant cause of fruit drop. The disease also causes a reduction in the useful life of the tree, weakened by defoliation and drying of the branches.
The main disease management strategy is to keep the Brevipalpus yothersi mite population at low levels by applying acaricides. The mite transmits the citrus leprosis virus, which mainly affects sweet orange trees. For this control to be more effective and longer lasting, adequate monitoring of the mite must be carried out, so that its population level is detected before and soon after the acaricide is applied. Failure to monitor the mite, in addition to delay in the application of the acaricide, lead to a reduction in the control period and the need for reapplication.
When applying acaricide, growers must use calibrated sprayers and have good coverage throughout the entire canopy of the plant. Special attention should be given to the inner parts and tops of trees.
Another fundamental point, according to Fundecitrus researcher Renato Bassanezi, is never to make repeated applications of acaricides with the same mode of action. “We have few efficient acaricides available to control the leprosis mite, and therefore we need to preserve them,” he warned.
To avoid the selection of resistant populations and the loss of acaricide efficiency, it is always necessary to rotate the applied products, alternating the modes of action. “Cases of leprosis mite resistant populations to acaricides have already been reported, but in most of them, when the acaricide was stopped and other acaricides with different modes of action were applied, that acaricide became efficient again,” Bassanezi said.
Other management measures can be adopted to increase the effectiveness of leprosis control, such as:
- Avoid mixing acaricide in a tank with incompatible products. If possible, apply the acaricide alone.
- To reduce multiplication of the mite, do not leave any remaining fruit on the tree after harvesting.
- Prune branches with disease symptoms to reduce the virus source.
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