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Early diagnosis

Biotechnology company creates test for identifying citrus sudden death

EDUARDO CESARDisease affects over one million orange treesEDUARDO CESAR

A quick and timely way of making a diagnosis of citrus sudden death (CSD), a new and mysterious disease that is threatening citriculture in São Paulo and the south of Minas Gerais and is capable of killing an orange tree in weeks, should shortly be offered to the producers. Alellyx, a private biotechnology company connected with the Brazilian Votorantim group, has developed a test that will make it possible to discover whether a tree has been infected by the causal agent of sudden death probably a mutation of the old citrus tristeza virus, a disease that in the 40s wiped out 80% of São Paulo’s orange trees before the first symptoms of the ailment manifests itself. “Our idea is to conclude an agreement for the provision of services with the sector, for us to apply a test on a representative sample of the orange groves in the state”, says Fernando Reinach, the president of Alellyx, who estimates the cost of a task of such a size at a few million reals.

Virus soup
According to Reinach, the company’s researchers have developed a new method for sequencing virus mixtures. This was important, because the pathogen of CSD does not seem to be a simple mutation of the old tristeza virus, but rather a soup of different mutant viruses. “We managed to identify the mutations”, he explains. Today, the diagnosis of CDS is always too late. Two years may go by between the moment the pathogen enters the tree and the appearance of the symptoms, such as the loss of shine on the leaves of the orange tree caused by the generalized clogging up of the system for carrying the sap from the crown to the roots. At this moment, the plant already shows a fall in productivity and, if, unless something is does, is on the way to its death. CDS has now hit over one million orange trees in the south of Minas and São Paulo, causing a losses of more than US$ 20 million for citriculture, which in the territory of São Paulo alone employs around 400,000 persons.

For engineer agronomist Marcos Antônio Machado, from the Sylvio Moreira Citrus Center, a public institution located in Cordeirópolis, in the interior of São Paulo, where research is also being done on the causal agent of sudden death and on ways of controlling the disease, it is not yet possible to know whether the test from Alellyx really works. “There is no doubt that the researchers from the company are good, but we do not know in detail what they have done”, explains Machado.

CDS is worrying and mobilizing. The São Paulo Secretariat for Agriculture and FAPESP are seeking forms of cooperation, to fight the disease. At the beginning of the year, a task force was created to study the etiology of the disease, to define characteristics of epidemiology, and to develop forms of control. One of the alternatives considered by the task force is the replacement of the rootstock. This solution, though, may have a negative impact on the production costs of oranges. At the same time that there is a quest for speeding up the researches, FAPESP is organizing an encounter amongst researchers from various institutions involved in this investigation to define a more effective structure for action.