What is in this article?:
- Growing citrus plants in approved protective structures is becoming an economical and regulatory mandate to protect the industry from insidious pests and diseases.
- The top pest and disease which threatens worldwide citrus production is the Asian citrus psyllid and Huanglongbing disease.
- “HLB is not just one of the most devastating citrus diseases; it is the most devastating disease."
Asian citrus psyllid
The phrase ‘Life on the Inside’ sounds like a movie profile about a convicted felon sentenced to prison without parole.
In reality, the phrase is the new status quo for U.S. citrus nursery growers and the theme of a recent workshop held in Ontario, Calif., sponsored by the California Citrus Nursery Board.
In the real world of citrus nursery production, growing citrus plants in approved protective structures is becoming an economical and regulatory mandate to protect the citrus industry from insidious pests and diseases which threaten the foundation of the industry’s future.
Today, the U.S. citrus industry employs 110,000 people from Florida to California with an economic value of $12.3 billion nationally including wholesalers, retailers, and other industries. About $4.7 billion is generated in annual wage income.
The top pest and disease combo which continues to threaten worldwide citrus production is the Asian citrus psyllid (ACP) insect, Diaphorina citri, and the bacterial Huanglongbing disease (HLB), Candidatus Liberibacter asiaticus, also called citrus greening.
The ACP is the primary vector of HLB yet the disease can be spread through grafting. ACP adults and nymphs carry the bacteria. The insect usually feeds on new plant flush.
Adult psyllids are one-eighth to one-sixth inch-brownish insects similar in size to an aphid. The insect feeds with its head down almost touching the surface of the leaf.
“HLB is not just one of the most devastating citrus diseases; it is the most devastating disease,” said Osama El-Lissy, director of emergency and domestic programs in the plant protection and quarantine unit with the USDA-Animal and Plant Health Inspection Service (APHIS) in Riverdale, Md.
“HLB will not only impact the industry economically - it will take out the industry,” said El-Lissy, the kick-off speaker at the California citrus nursery workshop. “There is no cure for HLB. An entire orchard can die in three years. That’s total destruction in a short period of time.”
The U.S. citrus industry is inundated with pests and diseases including HLB, citrus canker, citrus black spot, and sweet orange scab. Florida citrus growers battle all four organisms.
According to El-Lissy, financial losses to the Florida citrus industry total about $300 million annually from pests and diseases. Growers spend $500 per acre per year in pest control. Citrus diseases have increased production costs by 40 percent. The industry has survived the extra costs due to higher fruit prices.
HLB-caused tree death is tied to blocking nutrient movement through the phloem. The tree is choked and eventually starves to death. HLB symptoms include blotchy leaf mottling, yellowed leaves, and small, misshapen, sour-tasting fruit that is unmarketable.
The three HLB strains include Asian, African, and American. Brazil has the American strain while the U.S. has the Asian version.