For 10 years now, Brazil's top citrus-producing state, Sao Paulo, has faced one the world's most devastating citrus diseases, Huanglongbing (HLB). While the pathogen, spread by psyllid Diaphorina citri, has sent shock waves through some of the planet's top production zones, Sao Paulo has managed to get output back on track.

In a conversation with www.freshfruitportal.com, Fundecitrus researcher Renato Beozzo Bassanezi explained the methods that have been undertaken to keep Sao Paulo's industry afloat and economically viable.

"The adoption of control measures by a great majority of citrus producers has allowed incidence of plant disease to be maintained at a low level, below 15%. This includes grove renovation and adaption of more intensive management techniques for density, irrigation, fertilization and pest control," Beozzo said.

"This has kept production in Sao Paulo’s citrus district within historical levels. Sao Paulo has still not felt the impact of the disease on the general production of the state."

Put into context, Beozzo's 15% estimate of disease incidence equates to 96,800 affected hectares of citrus across 57 of Sao Paulo's 645 municipalities.

Successful management should not underplay the high costs undertaken by Sao Paulo's industry, however. Beozzo estimated 5% to 10% of the production value of each box of oranges (40.8kg) goes toward HLB management.

Additionally, between 2005 and 2013, approximately 35 million plants with disease symptoms were eradicated from the state.

Since HLB has no cure, Beozzo explained that extensive preventative measures have been the industry's saving grace.

"The first phytosanitary alert results show that the insect population has already begun to decline in certain regions. It’s an indication that when preventative control measures are executed efficiently, disease incidence can be stabilized," he said.

"Citrus producers during these 10 years that adopted a rigorous technological package suffered less than those who did not. In phytosanitary terms, citrus sustainability is directly proportional to the responsibility taken by each citrus grower."

He said control efforts have come down to three areas: acquisition of healthy seedlings grown in state-certified nurseries, control of the transmitting insect, and inspection and eradication of diseased plants.

Sao Paulo's citrus seedlings must be grown in nurseries with anti-insect screens - a policy that pre-dates the first HLB detection by one year and helped control the initial spread of the disease. Federal instructive IN53, established in 2008, also enforces the elimination of infected plants.

Regarding treatment, Beozzo said the industry has worked toward coordinated efforts to improve efficiency and minimize the environmental impact.

"With the support of notices, producers can organize joint action to combat the psyllid, such as sprays carried out across the region’s properties at the same time to help lower the population and avoid migration between neighboring properties and reducing re-infestation," he said.

"This way, the effect of spraying is more effective, less costly to the producer and less impactful on the environment."

On commercial farms, growers apply insecticides for population control. In residential or organic orchards, Fundecitrus has offered assistance in spreading parasitoid Tamarixia radiata to combat the disease-carrying psyllids.

In total, Sao Paulo has 8,224 monitoring points for HLB. The points provide data to map the spread of the disease and improve its control.

Thanks to continuously improving management techniques, Beozzo said Sao Paulo can be considered an HLB success story. The state continues to produce 70% of Brazil's oranges, keeping the world's glasses full of Brazilian fruit.

"For every five glasses of oranges consumed in the world, three of them come from Brazilian orchards. Citrus crops take up 1.2% of Brazil’s planted area. They are impressive numbers," Beozzo said.

He estimated that the Brazilian citrus industry generates 230,000 direct and indirect incomes, totaling US$378.4 million in salaries and US$189 million in tax revenue.

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