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Managing citrus greening

May 17, 2016

Citrus greening, or Huanglongbing (HLB), is a systemic bacterial disease that has ravaged the citrus industries in India, China and Southeast Asia for decades and is now a major problem in Brazil and the United States. Currently, there is no cure, and citrus trees that contract the disease die in as little as five years. By the time it is properly diagnosed, the disease has often spread to many of the surrounding trees.

HLB-infected citrus trees do not show symptoms during the first year of infection, so there is a long period of time when a grower cannot visually detect an infected tree — but the tree is still a source of bacteria that can spread to other trees via the Asian citrus psyllid. Controlling psyllids has become one of the primary strategies to prevent the spread of HLB.

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With no cure and no resistant citrus varieties available for HLB, certain strategies can still slow disease spread. These include planting disease-free nursery stock, removing infected trees, managing psyllids and promoting root health.

After initial transmission in the shoots, the HLB pathogen infects roots. This infection causes rapid fibrous root loss of up to 40 percent before symptoms appear in the canopy. Studies show that roots infected with Phytophthora spp. may interact with the bacterial infection in roots, compounding root damage and loss. To reduce crop decline from this disease interaction, growers can implement a root health treatment program with Ridomil Gold® SL fungicide. Ridomil Gold has direct fungicidal activity against Phytophthora root rot disease. Roots rapidly absorb the fungicide, which is then translocated throughout the root system, promoting root health, crop development and enhancing your chance to grow more citrus.

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Photos are either the property of Syngenta or used under agreement.