Citrus greening is a disease that is devastating millions of acres of citrus crops throughout the United States and has already killed massive quantities of citrus plants in Florida and surrounding states causing concern for the future of commercial citrus growers and citrus supply to the fruit juice industry.

With approximately 95% of all oranges grown in Florida being processed for juice (USDA/NASS 2015) and with Florida being largest orange-producing state in the United States, and the third largest orange producer in the world behind Brazil and China, the situation continues to be of concern to all sides of the industry and other large citrus producing states such as California.

The disease, originating from China and officially known as Huanglongbing (HLB) or yellow dragon disease, causes the leaves to yellow and the fruit to develop in a green, misshapen form. This ruins the fruit due to the increase in acidity and bitter taste making it unusable for the production of fruit juice. Yields from the infected trees are drastically cut before the tree very soon dies.

‘…the situation continues to be of concern to all sides of the industry and other large citrus producing states such as California’

Bleak future for the smaller growers

Small growers are being driven out of business by the fatal bacterial disease that is killing trees, production and profits. According to Kevin Bouffard, reporting in The Ledger last month, Florida citrus farmers who have been in the business for generations face a bleak future. The cost of growing a marketable crop in these conditions has risen substantially due to the extra fertiliser and pesticide needed to ward off the effects of the disease.

‘Small growers are being driven out of business by the fatal bacterial disease that is killing trees, production and profits’

According to a survey by Ariel Singerman, an agricultural economist at the Citrus Research and Education Center in Lake Alfred, the average cost for a 100 acre juice orange grove on the Central Florida Ridge, including Polk County, in the 2015-16 season has seen an increase in costs of more than 170% since the 2003-04 season

On the income side, ‘small growers just don’t have the negotiating heft’ to get the highest farm prices for their fruit. A large grower, who can promise to deliver millions of boxes of citrus fruit, will get the best farm prices from juice processors.

The United States Department of Agriculture (USDA) annually track the abandoned grove acreage and with the total standing at 130,684 in 2016 it is clear that many growers have gone out of business.

Another indicator is the declining membership in Florida’s largest grower’s representative, Florida Citrus Mutual, which has seen a drop of around 5000 members since the 1990’s from 11,000 to 6,000 in 2016. Small growers account for most of the loss commented Mutual’s CEO Michael Sparks.

California, the other major citrus growing region in the US has fortunately not seen the appearance of the disease yet, primarily due to stringent rules about the transportation of fruit which has kept the carrier of the disease – the Asian citrus psyllid (ACP) – contained in the Florida region.

Larry Black, a citrus grower from Lakeland, Florida, and former president of Florida Citrus Mutual, earlier last year urged the California growers to “get aggressive. Zero tolerance – don’t let this get away from you.”

Fighting back

Frequent pesticide spraying keeps down bug populations, and removing infected trees from groves and backyards can be an effective remedy. Scientists are working on the problem, said Ed Stover, a USDA research horticulturalist from Fort Pierce, Florida.

Some root stalks seem to produce trees that tolerate citrus greening disease, but the most promising research is in genetically engineering trees to resist the disease, he said.

Another avenue of hope is breeding tiny wasps that lay eggs in citrus psyllid larvae. Research is being done at the University of California, Riverside, USA.

Sources: The Fresno Bee, USA; USDA – United States Department of Agriculture, Animal and Plant Health Inspection Service; University of California, Division of Agriculture and Natural Resources, USA; The Ledger, Polk County and Central Florida, USA; Impact of Citrus Greening on Citrus Operations in Florida, Ariel Singerman and Pilar Useche