Disease threatens the citrus industry's viability

Zadie Neufville, Gleaner Writer

A CRISIS is looming in the citrus industry as the threat of a major greening disease sweeps across Jamaica. The disease is said to have the potential to wipe out the $3.7 billion citrus industry.

"With the bacteria which causes the disease and the vector already in Jamaica, farmers must be aware of the potential effects of greening," programme officer at the Jamaica Citrus Protection Agency (JCPA), Alfred Barrett, said.

Scientifically identified as the citrus huanglongbing, the citrus greening disease mainly affects young citrus trees. Affected plants show symptoms of blotchy, mottled leaves, which later progress across the entire canopy. Young diseased trees never come into production.

Found in three parishes

The disease is already present in the main citrus-producing parishes of St Mary, Clarendon and St Catherine.

The disease spreads at a rate of between 0.6 per cent and 40 per cent a year and is capable of killing fully grown trees within five years, Barrett said.

He added that younger trees are unable to withstand the disease and will die almost immediately.

"Controlling the disease with chemicals may require 12 or more sprayings a year, making it impossible to grow citrus," Barrett said.

He noted that the disease first appears at the edge of the groves usually closest to roadways, and spreads rapidly. Affected trees lose their productivity, fruits become smaller and fall off the trees, and the seeds appear black. The tree then dies.

The citrus industry was hit with the citrus tristeza virus in the 1990s, which forced many farmers to replace their trees.

Since the appearance of the disease here last year, Trade Winds Citrus Limited, a major citrus producer, has invested heavily in the control of citrus greening. The company has already built facilities dedicated to the control of the vector. All of the company's 2,700 acres of groves comprise trees that are less than 15 years old, as all were replaced as a result of the citrus tristeza virus.

Prepared

"We are a lot more prepared than the rest of the country," managing director Peter McConnell said, while noting that the company had instituted a combination of chemical and biological controls. The latter, he said, were introduced under the supervision of the Caribbean Agricultural Research Development Institute.

The regional research body, McConnell explained, had developed a parasitic wasp that is capable of controlling the citrus greening vector. The tiny wasp lays its eggs inside the body of the vector insect and kills it from inside out.

"The insects alone are too slow, chemicals alone are too costly, and there are also negative environmental effects with too many chemicals," McConnell added.

Used together, both chemical and biological controls seem to be working for Trade Winds, but Barrett is concerned that without funding to fight the disease, it will be more difficult, if not impossible, to control.

He pointed out that citrus greening disease is best controlled through coordinated spraying of neighbouring groves and those within a one to 1.5 mile radius.

This prevents reinfection of treated trees as the insect that carries the bacteria can fly up to 1.5 miles.

McConnell, who is also JCPA chairman, pointed to the immediate need for funding to combat the disease, given its devastating nature. He is willing to make his facilities available, but said it would take money to get a treatment programme going. The agency has trained some farmers and officers in the Ministry of Agriculture and the Rural Agricultural Development Authority on how to recognise the disease.

"The JCPA has the training and the knowledge, they just need the funds to carry out the work," he said, while adding that many farmers are unable to afford the cost of treatment.