HLB bacteria could destroy Spanish citrus in 15 years
The Comité de Gestion Citricos (CGC) warns that the arrival of the HLB bacteria would make the Spanish citrus industry disappear in 15 years. A report based on data on the progress of this disease in Florida (USA) warns that its settlement in Spain would halve domestic production within seven years. The insect that spreads this disease – which has no cure and that kills the trees in a few years –has extended its presence from Galicia to Lisbon (Portugal). The exporters demand immediate action to stop the rapid expansion and to reinforce the control to imported material that could be contaminated.
Citrus greening or Huanglongbing (HLB) is the main threat to citrus growing, but the Mediterranean is the only large productive area that, for the moment, has not been affected by the emergence of this bacterium. The situation turned upside down in 2014, when the presence in Galicia was confirmed, not of the disease but of one of the two vectors known to be capable of transmitting it, the Trioza erytreae. In 2015, the Portuguese authorities discovered another focus of this insect near Oporto. Today, four years later, this psyllid from Africa has travelled almost the entire Atlantic coast between La Coruña and the Lisbon area, 190 km from the first Spanish citrus plantations (Huelva) and only 170 km from the main producing province of citrus fruits of Portugal, the Algarve. Aware of the seriousness of the situation, the Citrus Management Committee (CGC), the national association that brings together private citrus exporters, has estimated the economic impact derived from the possible entry of this pathogen into the Spanish citrus industry. Their conclusions, given the inexistence of a cure and the experience contrasted in Florida (USA) -whose evolution has been extrapolated – are almost apocalyptic: in 7.5 years from its possible entry, the production of oranges, tangerines and lemons would be reduced by half (from 7 to 3.6 million tons) and in 15 years the citriculture would become a residual crop.
The report is based on the complete historical series of production data from 28 seasons in Florida, which is the only one that is available at that level of detail from among the main citrus powers affected by the disease (such as Mexico, Brazil, South Africa, La India or China). In the US state, the presence of the HLB was confirmed in 2005 but the disease must have settled years before: in the campaign 1997/98, Florida reached its production record with 12.3 million tons. At present, this figure has been reduced to 25%, with a little more than 3 million tons (see attached graph). In view of this progression, it is estimated that the production of Florida – the first producer of orange juice in the world – could disappear in the 2024/25 season (if there are no solutions to alleviate the disease beforehand).
The first season forecasts for Florida Citrus predict 70 million boxes of oranges and 9.6 million boxes of grapefruit.
That means a 14% drop in the state’s orange production and of 11.5% in grapefruit compared to last season.
The forecasts – issued by the National Agriculture Statistics Service of the US Department of Agriculture – were nevertheless welcomed by the Florida Department of Citrus executive director Shannon Shepp who said they represent the dedication and hard work of Florida’s citrus growers.
“In the face of significant challenges, they continue to push forward with new plantings and advanced agricultural techniques that allow them to maintain the viability of their groves. Citrus greening is a disease unlike any we have ever faced but the Florida Citrus industry will prevail,” Shepp said.
Florida Citrus Commission chairman and Lake Wales citrus grower Ellis Hunt welcomed the fact the forecast came in higher than initial estimates. “I’m looking forward to the day we can see this number start rising again,” Hunt said.
And State Rep. Ben Albritton, chairman of the agriculture and natural resources appropriations committee, said while the numbers are lower than last season’s crop, they keep Florida Citrus competitive and represent industry stability.
The US Department of Agriculture (USDA) has awarded $20.1 million in grants to university researchers for research and extension projects to help citrus producers fight Huanglongbing (HLB), commonly known as citrus greening disease.
According to a USDA press release, HLB was initially detected in Florida in 2005 and has since affected more than 75% of Florida citrus crops and threatens production across the US.
It has also been detected in Georgia, Louisiana, South Carolina, and Texas and several residential trees in California, as well as in Puerto Rico, the US Virgin Islands, and 14 states in Mexico. A total of 15 US states or territories are under full or partial quarantine due to the detected presence of the Asian citrus psyllid, a vector for HLB.
US Secretary of Agriculture Tom Vilsack said on Monday February 8: “The research and extension projects funded today bring us one step closer to providing growers real tools to fight this disease, from early detection to creating long-term solutions for the industry, producers and workers.”
Trees infected with citrus greening, but not treated with heat, have obvious disease symptoms and reduced productivity. (Photo by Marco Pitino via USDA)
Research at the University of Florida and Washington State University will focus on growing the putative pathogenic bacterium in artificial culture, which will greatly facilitate research efforts to manage HLB. Another project at the University of Florida will develop morpholino-based bactericides to reduce pathogen transmission and eliminate infections in existing trees. Research at the University of California will use virulence proteins from the pathogen to detect its presence before symptoms appear and to develop strategies for creating citrus rootstocks that are immune to HLB.
Top image of orange tree leaves with symptoms of Huanglongbing, also known as citrus greening disease, by Tim Gottwald via USDA