Brazilian citrus association Fundecitrus has alerted growers that proper management to combat citrus canker in orchards begins with leafminer control. The leafminer is a pest that has been present in Brazilian citriculture since 1996.
According to Fundecitrus researcher Franklin Behlau, the leafminer does not spread citrus canker disease from one plant to another or even to different parts of it. Rather, by feeding on the epidermis of plant tissue, the young form of the caterpillar forms sinuous galleries of a silver color on the limbs of young leaves and eventually on branches and fruits. “These wounds serve as an entry point for the canker-causing bacteria,” Behlau explained.
Wounds caused by leafminers are more easily infected and remain predisposed to the entry of bacteria that cause citrus canker for a longer period than mechanical injuries caused by wind or machines. This means that, in orchards where the disease is expanding, the wounds caused by the caterpillar increase the probability of the appearance of disease lesions in trees more distant from those initially affected. Therefore, the distribution of diseased trees becomes less aggregated. In addition, the leafminer increases the chances of citrus canker establishing itself in orchards that are still free of the disease.
The protection of shoots with insecticide during spring and summer is fundamental to avoid infestation of the orchards by the citrus leafminer. Adequate leafminer control contributes to more efficient management of citrus canker through regular copper applications. Further information can be obtained from the Citrus Canker Manual – Essential Control Measures, available for free download on the Fundecitrus website.
Fundecitrus added that with the arrival of rain, citrus growers’ attention turns to the occurrence of citrus canker. The disease affects the quality of the fruit, making it unviable for the commercial market.