Reducing damage to citrus crops said to require regional efforts

Expats who are trying to protect their citrus trees from a disease called greening or huanglongbing better make sure that their neighbors are doing so, too. And that includes distant neighbors.

In Costa Rica, the disease is called dragón amarillo. The Ministerio de Agricultura y Ganadería has declared an agricultural emergency over the problem.

Right now the main way of fighting the disease is to spray against the Asian citrus psyllid  (Diaphorina citri), a tiny bug that sucks on leaf sap and leaves behind bacteria.

Costa Rica has spent more than $1 million in prevention, training and the creation of a lab.

The cost of insecticides against the insect carrier is many hundreds of dollars a hectare, officials have said.

The situation has become so bad in Florida that some citrus growers have abandoned their fields, leaving their trees untended, which can have dire consequences for neighboring growers, said an entomology professor at the University of Florida.

A new article in the Journal of Economic Entomology shows that the insect can travel at least two kilometers in 12 days, and that they are able to traverse potential geographic barriers such as roads and fallow fields.

“The Asian citrus psyllid moves many kilometers,” said Lukasz Stelinski, the entomology professor and one of the co-authors. “If you control a small area and the other person does not, the psyllids will infest your area and can come from abandoned groves.” He was quoted on the Entomology Today Web site.

The researchers used a non-toxic chemical like soy protein to mark the insects in one grove. When the marked insect showed up in other groves, the distance traveled could be measured, noted the researchers in a summary prepared by Entomology Today.

The bacteria is Candidatus Liberibacter asiaticus, and the Chinese name reflects the fact that the disease was found in that country in the early part of the 20th century. After being infected, the leaves of citrus trees turn yellow and fall off. The disease also causes green and misshapen fruit.greeningbug020315

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