Factors That Impact Control of Citrus Leprosis

Daniel CooperBrazil, Diseases


Several factors can influence the period of citrus leprosis control after acaricide applications, according to a study by Daniel Andrade, a professor and researcher from São Paulo State University in Brazil. The research aimed to better understand how these factors can affect and increase the leprosis control period.

“We studied acaricides, the moment of application of the acaricide, the presence or absence of rain after applications, the infestation at the time of application, the volume of spray solution” and more, Andrade said.

Growers want a longer control period for leprosis. “The longer it is, the better it is for the citrus grower — the lower the cost and the fewer the applications,” Andrade said. “We concluded that depending on the season, there are different results for a given acaricide.”

The study showed that the period of control of Brevipalpus yothersi, the mite that transmits leprosis, provided by the application of acaricide is influenced by these variables:

  • Active ingredient
  • Time of application
  • Volume of spray solution
  • Level of infestation at the time of application
  • Occurrence of rain in the first days after application

In the northern region of São Paulo, the control period is longer when spray volumes of 151 to 200 mL/m³ are used and when the acaricide is applied with mite infestation levels of 1% to 5%.

Cyflumetofen has a longer control period than spirodiclofen in the absence of rain within seven days after application. Precipitation up to one day after application substantially reduces the period of cyflumetofen control.

Leprosis mainly affects sweet orange trees. It can cause production losses and reduce the useful life of the weakened tree. The disease affects tropical and subtropical regions and is restricted to the Americas. Cases have been reported in South America (Argentina, Brazil, Paraguay, Uruguay, Bolivia and Venezuela), more recently in Central America (Panama, Costa Rica, Nicaragua, El Salvador, Guatemala and Honduras) and in North America (Mexico).

In Brazil, leprosis was identified in 1933 in São Paulo. It occurs endemically in all areas of the São Paulo plateau, mainly in the north and northeast regions.

Source: Fundecitrus

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